Valves in petrochemical and refining installations are subject to numerous standards and specifications issued by many supporting organizations. Today’s valve standards are dynamic documents that reflect sound engineering practice, changes in market demands and changes in technology and manufacturing procedures.

This document focuses on some of the important standards that affect steel, gate, globe and check valves in refineries and petrochemical installations. Some mention will also be made of other valve specifications, however specifications for control and relief valves will not be covered.

Early in this century, when our nation’s petrochemical and refining industries were in their infancy, pipe, valve and fitting (PVF) manufacturers as well as end-users had no standards to go by. The design and function of their products were dictated and affected by actual feedback from the end user – be it years of effective service life, catastrophic failure or incompatibility with similar products from other manufacturers. This lack of valve, flange & fitting interchangeability with other manufacturers products, resulted in two primary groups addressing the standardization issue.

One group, The Manufacturers Standardization Society of the Valve & Fitting Industry (MSS), issued its first standard in 1924, and is still today at the forefront of valve standards activities. Over the years many MSS documents have been the basis for follow-up ASME and American Petroleum Institute (API) standards. The American Standards Association (ASA) published their first document covering standardized flanges and flanged fittings in 1927.

As the steam powered industrial revolution churned across the United States during the first quarter of this century, concern over boiler and pressure vessel design increased as some catastrophic disasters involving pressure vessels resulted in great loss of life and property. This situation led to the creation of the “Boiler Code”, which forever altered the future of all pressure containing components, including valves.

The “Boiler Code”, officially known as the American Society of Mechanical Engineers (ASME) Boiler & Pressure Vessel Code (B&PVC), laid the groundwork for many specifications and standards which have affected the PVF industry. The first edition of the Code was published in 1915. It is still published and updated yearly by ASME. Over the years the Code has come to assure manufacturers, designers and the public, of the safety and reliability of pressure equipment.

The fever pitch pace of oil & chemical production during world war II, dictated the creation of additional valve standards. The years immediately following the war saw the creation of many of the first edition of standards that are now in everyday use. The advent of pressure seal bonnet technology also required a new basis for determining pressure ratings of valves that led to standards such as MSS SP-66, “Pressure Ratings For Steel Buttwelding End Valves”.
The nuclear power industry of the 50′s & 60′s forced the creation of even more standards and specifications affecting the valve manufacturers and end-users. Today, increased concern for the environment, plant worker safety and the general public, has created valve standards that are technologically extensive and in many cases also legally driven.

All aspects of valve design, functionality, inspection and testing are covered in dozens of ASME, API and MSS documents. This dizzying amount of codes, standards and specifications can make the specification and procurement of valve products a job for only a seasoned valve engineering expert. Unfortunately, gold plated watches and summer retirement homes have taken their toll, by drastically reducing the number of experienced valve trained personnel familiar with valve specifications and standards.
This situation puts more responsibility on both the manufacturer and valve purchaser/specifier. A good understanding of the primary standards affecting these products is paramount. I recommend that anyone involved in specifying or purchasing valves have current copies of all the valve standards that apply to the products being purchased.

Here are capsule summaries of some of the more common valve specifications used in the petrochemical & refining industry today.

Gate Valves

For users of gate valves, API 600 is the key document. It details all design and material criteria. API 600 also lists important dimensions such as stem diameter minimums, wall thickness and stuffing box size.

Small carbon steel gate valves such as the forged 150#, 300#, 600#, 800# & 1500# class valves manufactured by several companies worldwide are covered by API 602. This specification covers the same details small forged gate valves that API 600 does for larger valves. API 602 further gives dimensions for extended body valves which are used extensively in industrial facilities.

Another important gate valve specification is ASME B16.34. This document gives extensive details on valves built to ASME boiler code pressure temperature ratings. One important area in which API 600 differs from ANSI B16.34 is minimum wall thickness. API 600 requires a heavier wall for a given pressure rating than does ASME B16.34. API 602 also requires a heavier wall for 150#, 300# & 600# classes than does B16.34.

Testing

Valve testing specifications have come a long way since the early days of the steel valve business. Looking through valve manufacturers’ catalogs of the 40′s and 50′s you see a multitude of pressure ratings and test pressures listed. Part of the problem was indeed lack of standardization. Many products were rated with working pressures (i.e.. 800 psi WOG – which meant 800 psi working pressure for water, oil or gas service), instead of the pressure classes we are accustomed to today. Standardized ASME/ANSI pressure classes have alleviated this confusion as to pressure/temperature ratings and test pressures for most steel valves.

The defacto test specification today is API 598 “Valve Inspection & Test”. First drafted in 1974, this document lists all of the test parameters and procedures to be followed for production testing of valves. Most metallic seated valves larger than ANSI 2″ size have an allowable leakage rate; this is listed in API 598 as well. Some valve types such as bronze gate, globe & check valves are usually not tested per API 598. These are normally tested per MSS SP-61 “Pressure Testing of Steel Valves”.

Occasionally the chemical or refinery valve specifier will see reference to API 6D – “Pipeline Valves”. This document is a thorough standard covering the design, materials and dimensions of valves for pipeline service. The most common reference for non-pipeline use are the testing requirements which differ slightly from API 598. The primary difference being 6D’s zero allowable leakage on closure tests. Since most of the valves built to API 6D are resilient seated, this is no problem, however when the test standard is applied to metallic seated wedge gate, globe or check valves, compliance can be difficult.

What about globe & check valve standards? Conspicuous in their absence are the steel globe and check valve standards. There is always some talk at valve industry gatherings about globe valve specifications, but so far there has been no action. Due to the inroads that quarter turn valves have made in a field once dominated by globe valves, there probably won’t be any specification in the near future. Most designers and specifiers will use ANSI B16.34 as far as applicable for their globe and check valve specifications. Great Britain’s British Standards Institute does have two standards that address globe valves: BS 1873 “Steel Globe Stop and Check Valves For The Petroleum, Petrochemical and Allied Industries” and BS 5352 “Steel Wedge Gate, Globe and Check Valves 50mm (2″) and Smaller For The Petroleum, Petrochemical an Allied Industries.
NACE MR0175

While not a standard, but a recommended practice, the National Association of Corrosion Engineers (NACE) specification MR-01-75, “Standard Material Requirements for Sulfide Stress Cracking Resistant Metallic Materials For Oilfield Equipment” is almost treated as a standard in many industries. MR-0175 was first published to help solve problems with material failures caused by the presence of hydrogen sulfide (H2S) in oil well equipment and gathering facilities. Although created as an “upstream” equipment document, MR0175 has been adopted by numerous industries and agencies. MR0175 lists materials (by UNS number) and fabrication techniques.

Designed to lessen the likelihood of H2S induced cracking, “NACE” trim as it is often called, is specified quite often for use in refinery processes. The most common “NACE” trim materials used in valve construction today are 316ss, Monel and Stellite.

ASME Codes

Although not valve standards as such, there are three important ASME documents that are important to fabricators welding valves into piping components and manufacturers utilizing welding in the manufacturing process.

First is ASME B&PVC, Section IX “Welding & Brazing Qualifications”. This document addresses welding procedures, welding procedure qualifications and welder certifications. Most, if not all, pressure vessel welding codes specify Section IX as part of their process.
The other two are “construction” codes. ANSI/ASME B31.3 “Chemical Plant And Petroleum Refinery Piping”, details the fabrication, assembly and nondestructive testing of piping systems, which include valves. Many valve manufacturers utilize B31.3 for their in-house fabrication procedures. The other construction code is Section VIII, “Rules For The Construction of Pressure Vessels – Division 1″, of the B&PVC. Code. Section VIII also details fabrication, assembly and nondestructive testing requirements. There are additional construction codes used for pipeline, power and refrigerated piping industries.

Several non-domestic standards organizations publish valve standards, including the British Standards Institute (BSI), International Standards Organization (ISO) and The Canadian Standards Organization (CSA). BSI publishes several standards covering areas that U.S. valve standards writers have ignored such as: globe valves – BS 1873 & BS 5352, cryogenic valves – BS 6364 and steel check valves – BS 1868 & BS 5352. These documents are excellent starting points for persons needing guidance in these particular areas.

The Future For U.S. Valve Standards

What does the future hold for United States valve standards? As more and more valve production moves to foreign soil, unfortunately so does some of the power to direct and control valve standards. During the past several years there has been cooperation between the International Standards Organization (ISO) and US valve standards makers, however some domestic standards making bodies have justifiably been reluctant to give up total control of documents they have invested much time, effort and expense in creating, for a return of relatively nothing.

The biggest dark cloud over the horizon for domestic standards organizations is the debate over metrification. If future valve and fitting standards take on more of an ISO flavor, the costs could be considerable. Metrification can be either “soft” or “hard” in terms of change from our imperial measuring units. Soft metrification merely changes the current unit of measurement to metric while maintaining the actual measurements. Hard metrification on the other hand, will not only change units of measure, but actually change dimensions. Obviously hard metrification is a major economic factor to be faced by valve manufacturers and end-users currently using or manufacturing valves and fittings.

All of the specifications listed in this article can be ordered from the sponsoring agencies, but there are other sources as well. Information Handling Services (IHS) in Englewood, Colorado offers many standards packages on CD ROM. There are many advantages to having the specification on computer, such as the ability to look up subjects by key word. However the biggest advantage has to be the automatic yearly update service, which insures you always have the latest copy of each cataloged specification. This update service helps meet the “most current document” requirements of ISO 9000 quality programs.

Two technical bookshops that carry extensive inventories of standards and specifications are Brown Book Shop in Houston, TX and Global Engineering Documents in Englewood, CO. Global also has a large inventory of obsolete and out-of-date specifications.
Over seventy-five years of valve standards have helped the refining and petrochemical industries grow and prosper throughout the world, with assured interchangeability of products by different manufacturers, as well as timely design changes. The committees that formulate these standards are hard working volunteers who care a great deal for their industries and the people affected by them. Standards committee meetings sometimes take on the air of a hearty democrat vs. republican congressional debate, but as the manufacturers state their case and the end-users theirs; the end result usually ends in acceptable compromise.

As long as these concerned, motivated industry representatives are writing the standards we must all work with, the industry can feel secure that present and future valve specifications will reflect the changing needs of the industry and the general public.

During the boom times of the 50’s and early 60’s the valve repair industry took root and blossomed, as end-users began to divest themselves of most valve repair functions. The emergence of dozens of small to medium sized valve repair companies all across the country helped fill the vacuum left by the closing of the plant owned valve repair shops. A few manufacturers such as Crane and Pacific got in on the repair action by establishing their own service centers at select locations around the country.

It was actually easier to repair valves back then. The basic design of steel valves manufactured in the United States changed little for the first 75 years of the 20th century. Due to their over-engineering, in the days before finite element analysis (FEA), many of these “tanks” held up to decades of service, as well as many repair cycles. Ask virtually any long-time valve repair hand, and most will choose to repair a 40 year-old cast steel gate valve, rather than one of the newer designs.

Inexpensive imports began replacing the domestic products as the 70’s turned into the 80’s. During this period, some of the major valve manufacturers saw the advantage of authorizing independent valve shops to repair and modify their products. These authorized facilities helped provide an ever-improving level of service for the end-user community. Finally, a repair facility could get information that was previously considered proprietary, yet was necessary to correctly service a manufacturers product. The net result was better service to the end-users.

As the quantity of valve repair and service increased, so did the level of bogus and fraudulent valve work and product misrepresentation. Valve repair companies with only a desire to make a quick buck proliferated through the 80’s. The “bogus valve” epidemic culminated in several successful lawsuits, as manufacturers sought to regain some of their lost prestige. Prestige lost at the hands of crooks who made valves new again merely by attaching a new fraudulent tag.

In 1990, the Valve Manufacturers of America (VMA) established the Valve Repair Council (VRC) to help protect its members and customers from the hazards of improperly repaired bogus and counterfeit valves. The formation of the VRC helped end-users to choose quality valve repair facilities. To be a member of the VRC, a valve shop has to be sponsored by a VMA member as well as submit to an independent quality audit.
Repair Standards & API RP 621

Traditionally, the repair standard or specification was provided to the repair shop by the end-user. This resulted in repair shops maintaining an inventory of many different valve repair documents. While the standards were different, they had many points in common. In an effort to try to standardize their valve repair specifications and thus lower valve repair costs, end-users and valve repair shops established an ad-hoc committee charged with creating a common valve repair standard. Companies such as Exxon, Shell, Dow and others initially agreed to a basic common repair document. This basic document was then presented to API for possible conversion into an API standard. An API work group was formed and the document, API Recommended Practice 621 “Reconditioning of Metallic Gate, Globe and Check Valves”, was created.

Adoption of API 621 was not easy. There was a very real battle between the end-user community and the valve manufacturers. The primary concern voiced by the manufacturing community was the increased liability that such a document might create for them, since deviations from original manufacturing dimensions are allowed in the document. Key areas of deviation include: valve end-to-end dimensions, flange thickness, shell wall thickness and stem diameter.

Another manufacturer concern was that valve refurbishers would use the document in order to sell more rebuilt product to end-users. Although the document states in its scope: “This RP does not cover reconditioning or remanufacturing of used or surplus valves intended for resale. The only intent of this RP is to provide guidelines for refurbishing an end-user’s (Owner) valves for continued service in the Owner’s facility.” To gain increased legitimacy of his product, the potential rebuilder/seller could say that his valves were rebuilt in accordance with API RP 621. If this does occur and the valves were rebuilt in accordance to the guidelines of RP 621, at least the valves would have been rebuilt to a baseline standard where none existed before.

Now for the first time, there is a standardized procedure for the repair of gate, globe & check valves. This should streamline the valve repair quotation process, as well as elevate the overall quality of valve repair. RP 621 will also help separate the “wheat from the chaff” when it comes to specifying a valve service provider. The standard contains requirements that cannot now be met by some of the lower end valve repair companies. These companies will have to add additional equipment and/or expertise in order to repair valves to the new specification. As RP 621 becomes adopted by more and more end-users, the net result should be a distinct increase in the quality of valve repair.

The “Valve” Information Age

Today, the valve repair/service function can provide much more than properly repaired valves. It can provide valuable product information and feedback. Today’s state of the art valve repair programs are designed to record, through a series of visual inspections and measurements, valuable data on how a particular valve performs in service over time. Some of the more common measurements include: valve end-to-end dimension, flange thickness, stem diameter, stuffing box diameter and wall thickness at multiple locations. By comparing the data after each repair “turn”, the repair facility can provide valuable cost saving data to the end-user/owner on how particular valve brands, sizes and types perform. For example, armed with this data, the end-user can weed out valve manufacturers from its Acceptable Manufacturers List (AML) whose valves are consistently unrepairable, or due to design idiosyncrasies are just too expensive to repair. All top-notch valve repair facilities have shop floor computer systems to easily gather and collect this information.

The general economic rule of thumb for the repairability of a valve is not to exceed 50% of the new valve replacement price. For “commodity” type gate, globe & check valves, the repair costs on the Gulf Coast run anywhere from 40% to 75% of new valve costs, depending upon size, material and pressure class. With today’s influx of inexpensive imports, the cost of repairing the smaller (2” – 6”) plain carbon steel valves exceeds the 50% rule more often than not. However, due to corners cut in manufacturing, these inexpensive valves are scrapped rather than repaired at a much higher rate. The end result is that after a period of years the inexpensive valve may have to be replaced more often than the more heartily built valve with a higher original cost. Other factors such as stem-to-wedge guiding, seat geometry and shell design make certain valves more expensive to repair than others.

Choosing a Repair Facility

If your company is considering a valve repair program, the first consideration is choosing the right repair facility. In years past, many valve repair contracts were let to the company that was either the lowest bidder or had the biggest bass boat. Fortunately the “Bubba” era of valve repair facility selection is just about gone, having been replaced by quality, capability and OEM authorizations.

The first criteria for choosing a valve service vendor should be membership in the Valve Repair Council (VRC). By choosing a VRC member you are getting a pre-qualified service company that has been recognized for its quality and service level. For example, there are 55 valve repair companies listed in the Greater Houston Yellow Pages; only four are members of the VRC. They are: United Valve, Paradigm Valve Services, Crane-Groth Valve Services & Kirksey Machine. These member companies provide varied services on virtually every type of valve and actuator.

The next consideration for choosing a valve service provider should be factory authorizations and alliances with the manufacturers of predominant or key valves in your plant. These authorizations ensure the best possible flow of spare parts and engineering support between the manufacturer and the valve service provider, which is so important with today’s high performance quarter turn products. Improper repair of some of these highly engineered valves can be catastrophic.

Virtually every reputable valve shop will have a well-documented quality program. Some may even have ISO 9000 certification. At the very least the valve service provider should demonstrate that they have the following quality system components:

1. Quality Assurance Manual
2. Quality Procedures
3. Shop Procedures
4. Welding Procedures in accordance with ASME Section IX and ASME B31.3
5. Welder qualifications in accordance with ASME Section IX
6. Computer system for tracking work through the shop
7. Traceability system for all raw materials
8. System for tracking non-conformances & corrective action

Valve Shop Equipment

Equipment and facilities are important criteria when choosing a valve service provider. A clean well-lit shop environment not only makes a good first impression, but is a good indicator that the facility takes pride in its workmanship. Since valve repair often involves machining and welding operations, this equipment should be inspected for service suitability and capacity. If you have large (NPS 24” and up) diameter valves that need repair, look for a facility with large boring mills and lathes, as well as a good five ton or better overhead crane system. If your valves are not large, say NPS 6” and smaller, the large machines and cranes are obviously not necessary. Newer lathes, milling machines and CNC machining centers are a good sign that the valve shop strives for the highest quality from its machining department.

The weld shop should contain a variety of welding machines, fixtures and positioners to allow the welding to be done in the most productive manner. The presence of welding processes such as submerged arc welding (SAW), Tungsten Inert Gas (TIG) and flux-cored arc welding (FCAW) usually denote a fully capable and equipped welding shop. There should also be digital temperature measuring devices or heat sensitive crayons present to confirm preheat and interpass temperatures.

Many welding procedures require a post weld heat treatment (PWHT) following welding. This requires furnaces of adequate size, or in some cases, localized stress relief equipment. Welding of Chrome/Moly valves or valves for NACE MR0175 sour service require PWHT in almost every case. The best-equipped shops will have their own ovens to perform this process in-house.

Cleaning and assembly areas should be spacious and not encroach upon the machining and welding areas. Shot and sand blasting generate dust and debris that can damage finished machined surfaces. These operations should be separated from other areas of the shop. The assembly areas should have cranes sufficient to handle the largest valves worked on in the facility.

Nondestructive evaluation (NDE) and inspection equipment is now standard fare for quality valve service companies. This equipment ranges from the very basic dye penetrant kits to in-house x-ray radiography. Here are some NDE and inspection items present in valves shops today:

BASIC EQUIPMENT

1) Portable Rockwell hardness test machine
2) Bench type Rockwell or Brinell hardness test machine
3) Granite surface plate
4) Dye Penetrant (PT) testing kit
5) Ultrasonic “D meter” for wall thickness measurement
6) Positive Material Identification (PMI) machine for alloy verification

ADDED EQUIPMENT

1) Magnetic Particle (MT) yokes
2) Electronic surface roughness indicator
3) Electronic hardness tester

Well Equipped

1) Ultrasonic flaw detector
2) Radiographic facility
3) Helium or Methane leak detector for fugitive emissions testing

Following reassembly, all valves need to be pressure tested. The well-equipped shop should have a variety of valve testing machines to handle valves of all types and pressures. In valve testing, one size test machine does not fit all. If the shop will be testing buttweld valves, special mechanical or hydraulic ram type machines with multiple end adapters are required. While in some cases a valve may be tested by bolting flanges on, this is a very time consuming and costly method of production testing of repaired valves.

The Future of Valve Repair

If you have been in the valve business for any length of time, you know the one constant you can count on is change. The once dominant list of domestic valve manufacturers has now shrunk to a precious few, while their customers, the end-users, have shrunk themselves through the mergers and acquisitions of the last 10 years or so. The valve repair industry is also in a state of change. “Merger Mania” has hit the industry during the past two years and shows no signs of letting up.

In the past, repair programs were usually local in nature, with the local plants contracting a local repair vendor. However, with the number of end-user mergers, the number of contracts has shrunk proportionally. Some of the larger end-user companies are now contracting with a single valve service company to handle all of their repair and service work on a national or even global basis.

One trend that is becoming more prevalent is the acquisition of valve service shops by some of the larger diversified valve manufacturers. It remains to be seen how an industry that has traditionally been centered on customer service and one-on-one relationships fares, as the realities of large corporate bureaucracy are instilled upon them.

Another growing trend in the valve repair industry is the Valve Management Program. Although the details can vary, and are custom tailored to the needs of the particular end-user, the program creates a single source for all valve related activity. This can include new valve pre-testing, valve modification and repair. Aside from lowered costs, these programs allow the end-user much greater control over the valves that enter the plant. New valve pre-testing programs serve as an additional QA inspection that often catches problems that slipped through the manufacturers testing and inspection programs. The modification of valves for special service applications becomes interactive, as the plant engineering department and the repair/service facility engineers communicate closely to solve valve related issues. Additionally, more valve information is gleaned as pre-tested valves are serialized and dimensionally checked prior to installation.

Although the playing field, as well as some of the rules are changing, the basics of repairing valves to extend their service life is still the same. Valve repair in the 21st Century promises to be technologically advanced, with data and digital imagery being exchanged between the repair facility and the end-user. But when you break the repair process down to the lowest level, there will still be skilled valve technicians armed with a set of wrenches and a tube of “Prussian Blue”, performing basic operations that have changed little over the past 100 years.

As an engineer or technician you probably have to deal with valves everyday. Depending upon your job description, you may have to specify, maintain, install, operate or repair any number and type of valves. That is a lot of responsibility. And if you don’t know all the answers, you have to get some help. But whom do you ask? Where do you look?

If you had a tough valve application questions 10-20 years ago, there was probably someone in your organization that held the unofficial title of ‘valve guru’, and he would have the answers based on his years of experience and focused interest. Sadly, the gold watches have taken their toll, and most of these guys have transitioned to the back nine or the back bay.

So where do you turn? Fortunately there is a lot of good information out there. Hopefully this article will give you a few insider tips, as well as point you in the right informational direction.

Everyone involved with the chemical processing industry is concerned about safety. Two of the guiding principles of the CMA Responsible Care Initiative are: “To make health, safety and environmental considerations a priority in our planning for all existing and new products and processes”. And “To operate our plants and facilities in a manner that protects the environment and the health and safety of our employees and the public”. To this end, the quality, integrity and suitability of the valves in the process line must be considered.

OSHA 1910.119 “Process Safety Management of Highly Hazardous Chemicals” loudly echoes the spirit of the CMA initiative. The purpose of section 1910.119 is stated as follows: “This section contains requirements for the preventing or minimizing the consequences of catastrophic releases of toxic, reactive, flammable, or explosive chemicals.” As a valve owner or a person responsible for valve integrity in your plant, that puts a huge burden on you to make the right valve decisions. You have to know that the valve is the right valve for the application and that the materials are suitable for the service media, pressure and temperature.

Additional Testing- Added Insurance

For many generic processes, ample history and application data is available, but some critical services require a measure of added insurance. This can take the form of additional testing requirements for the valves you purchase.

For example, say your operating conditions require a shut-off valve to function at –320^oF. This temperature dictates the use of a cryogenic valve with a gas column to shield the stuffing box or packing area from the sub-zero cold and possible icing, which could render the valve inoperable. You must be sure that the valve of choice actually functions as required at the –320^oF temperature.

You have two choices. You can trust the judgment of everyone in the supply chain or you can ask to see the cryogenic test results for the valve you are considering. You would learn by reviewing the test data, that valves don’t always perform the same at cryogenic temperatures as they do at room temperature.

Fugitive emissions issues are at the forefront today and valves have been identified as some of the primary culprits. If you have any concerns about the integrity of a valve’s seals and gaskets, ask the manufacturer for copies of fugitive emissions test reports performed on the valve you would like to purchase. The most common fugitive emissions testing procedure performed today is ANSI/ISA 93.00.01-1999, “Standard Method for the Evaluation of External Leakage of Manual and Automated On-Off Valves”. If the report references this specification, you can be comfortable with the scope of the tests.

In addition to this qualification testing, you can have the manufacturer or a valve service company perform fugitive emission testing with either helium or methane on a production basis. There are extra charges for these tests, but if the service is critical, the cost can be easily justified.

When the highest valve component integrity is required, additional nondestructive testing (NDE) can be specified. NDE, including radiography (RT), magnetic particle (MT), ultrasonic inspection (UT) and dye Penetrant examination (PT) is useful for detecting flaws and defects in castings, forgings and wrought materials. If material identification is a concern, a positive material identification (PMI) can be performed on key valve components to confirm their identity.

Special Service Cleaning

Some media, such as oxygen, require that all piping and components be totally free of oil and other contaminates. To achieve this clean state, valves must be completely disassembled and cleaned, utilizing special chemicals, equipment and inspection techniques. Following disassembly and individual parts cleaning, each part is checked with a black light and reassembled in a dust and oil free environment.

After assembly, the valves are usually tested again with either nitrogen or helium. The cleaned and tested valves are then packaged in a heavy plastic bag that is sealed for shipment to the customer. Valve cleaning is very often used for other services, such as chlorine and ethylene oxide, that require an absolutely pristine valve.

Installation Tips

What about valve installation? That should be fairly straight forward, right? Actually if you take care and follow all manufacturers installation procedures and recommendations, you should be fine. However, if there are no installation procedures provided by the manufacturer, you could use a little help. The Manufacturers Standardization Society of the Valve & Fitting Industry, otherwise known as MSS, publishes a document called the “MSS Valve User Guide” (MSS SP-92). This document has a wealth of information concerning installation operation and maintenance of various types of valves.

For users of higher alloys, attention must be paid to the weldability of the material for socketweld connections. Due to their microstructure and chemistry, wrought and forged materials are generally very weldable. However the same materials in the cast condition may not weld so easily due to cracking in the heat affected zone of the weld. Alloys such as CN7M (Alloy 20), M35 (Monel) and CY40 (Inconel) have suffered from this condition. As a precaution, a PT inspection should be performed after welding the valve into the pipe run.

Valve Repair

Like any other mechanical device, valves eventually need repair or replacement. The frequency of this R&R depends upon the severity of the operating conditions, the design of the valve and the preventive maintenance that has been performed. There are documented cases where valves originally installed at the turn of the century are still operating fine. There are also cases where the environment is so severe, that valves only last a couple of weeks before they need to be repaired.

Although complete replacement sounds like the easiest method, it may not be the best choice. First of all, the cost will be high and second, if the valve is not a commodity type valve, the delivery from the manufacturer may be long.

In addition to a few OEM’s that repair their own products, there are quality independent valve repair companies in most parts of the United States. Many companies say they repair valves, but with the complexity of some of today’s quarter turn products, you need to be sure the company you are dealing with is qualified to handle the job. The Valve Manufacturers Association of America (VMA) created The Valve Repair Council (VRC) 12 years ago to provide a network of OEM authorized and audited valve repair facilities. The 30 members of the VRC are the cream-of-the-crop when it comes to valve repair. So when you are looking for a valve repair facility, look for the VRC authorization.

What does it cost to repair a valve? There is no common answer due to the differences in valve types, however a good rule of thumb for most valves is that the repair will cost anywhere between 40% and 60% of the cost of a new valve.

When specifying new valves it is often important to consider the repairability of a particular type or brand. Oftentimes, that temptingly cheap valve may be difficult or impossible to repair due to design flaws or the high cost and/or lack of availability of parts. When considering a new valve purchase you should look at the total cost of ownership, not just the original purchase price.

Press F1 For Help

Most valve manufacturers and distributors are usually glad to offer valve application or operation assistance. However you must consider that the salesman may not have the engineering background to answer specific technical questions. Due to liability concerns, even some manufacturers are hesitant to go out too far on that informational limb. It is also very unlikely that one manufacturer will give you much information about a competitor’s product. If you have several different brands from different distributors, your information search may turn into more of a scavenger hunt.

More survival help can be found in the publications of the various standards making organizations. Virtually all valves are built to both material specifications and one or more industry codes or standards. There are standards and specifications covering virtually every type of valve from plastic industrial ball valves to instrument valves. While the primary purpose of these documents is to produce standardized products, there is a wealth of general information contained in their pages. These documents and the organizations that publish them are a good starting point.

For control valves, the primary organization is The Instrument Society of America (ISA). ISA has a number of standards that deal with control valves, from end-to-end dimensions to testing requirements. The organization also offers control valve training courses at various sites around the country.

The oldest valve standards-making organization in the United States is MSS. Their first standard was published in 1924 and the organization estimates that it has distributed over 50,000 standards documents during its 78-year history. The MSS inventory currently includes 72 valve related standards.

The American Petroleum Institute (API) publishes several valve standards. Gate valves, ball valves, corrosion resistant gate valves and valve inspection & testing are some of the topics covered by their standards.

The American Society of Mechanical Engineers (ASME) has a long history of standards creation and stewardship. The most important ASME valve document is B16.34, “Valves- Flanged, Threaded and Welding End”. The heart of the document is the 60 page pressure-temperature ratings section. These tables cover virtually all of the common valve materials in use today including stainless steels and nickel alloys. B16.34 also contains design information and non-destructive inspection procedures.

The American Society for Testing & Materials (ASTM) does not publish valve standards, but they do produce the material specifications used for the manufacture of the valve components.

Historically, valve standards have been dominated by the above-mentioned standards making bodies, however the landscape is changing. Increasing international participation, combined with decreasing US participation has opened the door to ISO valve standards acceptance worldwide. In some cases US standards have been adopted verbatim, but the current trend is to totally new documents created from scratch by European dominated committees.

Bookshelf Items

Much like squirrels storing acorns for the winter, most engineers seem to store information (books, reports, pamphlets, etc.) for possible later reference. When it comes to valves, there are some excellent volumes available to help keep that bookshelf firmly anchored to the floor. During the past 20 years eight excellent valve books have been published.

Control Valve Selection and Sizing, by Les Driskell, Instrument Society of America, ISBN 0-87664-628-3. This is the control valve bible. Virtually everything you need to know about these valves is there from sizing to trim types and applications.

The Valve Primer, by Brent T. Stojkov, Industrial Press, ISBN 0-8311-3077-6. This little book (4.5” x 7”) is not only easy to carry around, but is the best basic valve book available.

The Chemical Engineering Guide to Valves, by Richard Greene & Chemical Engineering Magazine, McGraw-Hill, ISBN 0-07-024313-1. This book is a compilation of various reprints from Chemical Engineering magazine. Highlights include excellent articles on valve installation and selecting and specifying valves for new plants.

Valve & Actuator Technology, by Wayne Ulanksi, McGraw-Hill, ISBN 0-07-019477-7. While containing a lot of basic valve information, Ulanski’s book focuses much of its attention on valve actuation.

Valve Handbook, by Philip Skousen, McGraw-Hill, ISBN 0-07-057921-0. This handbook almost takes two hands to lift. Its 726 pages cover virtually all valve subjects. A complete reference work, although slightly heavy on the control valve material.

The Valve Book, edited by Pirjo Sparig, Neles-Jamesbury, As you might expect from ball valve giant Neles-Jamesbury, this book is heavy on quarter-turn valves. Highlights include much data on seat construction and operation, including offset types.

Lyon’s Encyclopedia of Valves, by Jerry Lyons & Carl Askland, Van Nostrand Reinhold, ISBN 0-442-24961-6. The Lyon’s book is truly a reference work with most of its pages devoted to a valve terminology glossary and fluid power symbols.

Valve Selection and Specification Guide, by Ronald C. Merrick, Von Nostrand Reinhold, ISBN 0-442-31870-7. Merrick’s book is different from the other texts in that he gives extra attention to valve specifications and procurement. The volume also contains a good basic valve overview, with a focus on construction details.

Although not valve books per se, there are two excellent general corrosion books available, to help you make sound material selections. Corrosion Control in The Chemical Process Industries, by C.P. Dillon and published by the Metals Technology Institute of the Chemical Process Industries, is a great overview of chemical process corrosion and materials. Corrosion in the Petrochemical Industrypublished by ASM International is probably the best overall chemical and petrochemical corrosion book. Its 500 pages cover materials, case histories and forms of corrosion.

Since the valve book market is small, most of the above mentioned books are not always available at technical bookstores. However they are usually easily located on the Internet used book marketplace at sites such as www.bookfinder.com.

It would be nice if all the valve information we were searching was available on-line. But so far there is only a smattering of easily obtainable data. Most of what is there is available on manufacturers websites. Many of these sites now offer PDF catalog and document downloading.

Reference books and documents will never replace practical valve experience, but the combination of the two might help create the next “valve guru” in your organization. If there is a local valve service facility, call and get acquainted, these guys are the front lines of valve technology and most are glad to offer assistance or even have you come into their shop for some hands-on experience.

Armed with a good attitude and the right survival gear you can brave the valve jungle. Don’t be afraid to ask when you don’t know and remember that it is your responsibility to care about the valves under your control.

Valve modification can be defined as adding value to standard or commodity valves, generally gate, globe, check & ball valves, by the installation of special trims, end-connections, packing & gaskets and other accessories or upgrades not provided on the original product. All of these operations can of course be performed by the OEM; however the average required turnaround time on valve modification orders today is 5-7 working days, compared to the standard multi-week manufacturer’s lead times. These items are usually shorts that had been missed on the original project valve take-off lists or they are needed for routine MRO activity. In all cases, delivery time is of the essence and there is rarely enough time to allow for overseas shipping.

History

To understand the genesis of the valve modification industry in the United States, a little history is in order. Valve supply through the 50’s and 60’s was fairly steady and the procurement philosophy of the end-user was to order early and keep extras in stock. Virtually every plant on the Gulf Coast had a storehouse loaded with a variety of spare valves, including specials. But belt-tightening measures by the end-users, which lowered their inventories, combined with the petrochemical construction boom of the 70’s, exceeded the delivery capability of domestic manufacturers for commodity and particularly, “special” valves.

Faced with the expense of stocking a huge variety of slower-turning specials, the distributors would generally just stock “vanilla” valves and have a local valve shop re-trim or install new packing and gaskets to meet customer requirements. In those days, typical deliveries for modification orders were 4-6 weeks, due to the size of the orders. Comparatively, today’s modification work deliveries run less than a week. During this period, the OEM’s would tolerate the aftermarket work on their products because they were reaping the benefit of the sale of the stock valves.

In the late 70’s, the steel valve business in the United States began perhaps its most dramatic metamorphosis, as a new entity, the imported valve, made its way upon the American scene in force. Huge worldwide petrochemical and refining projects totally depleted the U.S. valve manufacturer’s production capacity and forced them to look elsewhere to meet domestic valve demand. Valves from Italy, Eastern Europe, Japan and Korea helped fill the gap. These imported valves were rarely brought into the U.S. in anything other than standard trim, so valve service companies prospered from the additional modification work they created.

Up until this time, the modification of a valve was generally frowned upon by the OEM’s. However, they soon began to see the advantages of auditing and authorizing quality valve service facilities to perform modification work on their products. With an official authorization program, the OEM would retain some oversight of the aftermarket work performed on their products, plus reduce the number of bogus operations performed on their valves.

There have been several lawsuits filed in the United States concerning unauthorized modification of OEM products. These suits were the result of poor workmanship which resulted in personal and/or property damage. Some examples of this bogus work include: welding overlays for sour service that received no PWHT and cracked in service; stems fabricated by welding the old (13 Cr) stem foot on to a new 316ss shaft and failing due to severe corrosion; cryogenic valves fabricated without design calculations that resulted in joint failure. The OEM authorization program has gone a long way in diminishing these kinds of claims.

The two pioneers of the authorized modification shop concept were Kitz & Velan, both of which began official authorization programs in the early 80’s. Relationships between OEM’s and authorized valve shops expanded further in the 90’s as well equipped authorized valve shops became essential tools in the overall OEM marketing focus.

Gaining OEM Approval

The most common way a valve shop is approved is through an audit process. The audit is normally conducted by the QA Manager of the OEM or an appointed audit team. At the very least, the audit will examine all of the quality and procedural documents of a potential organization. While ISO 9001 or 9002 certification is not required by the OEMs, an ISO or API Q1 based quality system is a must. Additionally, specific shop procedures are also reviewed. Needless to say having a good reputation in the industry is also helpful in gaining OEM approval. Virtually all of the quality modification shops in the United States are also members of the Valve Repair Council, an organization sponsored by the Valve Manufacturers Association of America.

In the US, the valve modification business is logically focused in the Gulf Coast area, where several major PVF distributors are headquartered. The proximity of the area refining and petrochemical industry also makes this location even more viable for valve modification companies. I would estimate that more new valve modification work is performed in the Houston area than in all of the other regions of the US combined.

‘Mod Shops’

Today’s valve modification service provider is a far cry from the blacksmith like valve shops of the 40’s and 50’s. Since the modification shop has to respond quickly, vertical integration is very important to the overall success of the shop. Walking through the doors of the highest caliber shops today, you will find manual and CNC machine tools, AutoCAD software, submerged-arc and fluxed-core welding, heat treatment furnaces of all sizes, in-house nondestructive evaluation and elaborate testing facilities, all tied together via sophisticated computer tracking systems. In-house engineering is also important and mechanical and welding engineers are likely to be found in many of these shops as well.

Just what types of work are performed in these facilities? Virtually any special valve that is offered by an OEM can be created in the best ‘mod-shops’ or trim-shops, as they are called in the Houston area. Here are few of the more common jobs performed regularly by United Valve, a leading provider of valve modification services in the Houston area:

Trim changes on cast and forged steel valves
Bore schedule changes on BWE valves
Raised face to RTJ ends
Cryogenic gas column fabrication
Elastomer seating inserts
Special packing & gaskets
Fugitive emissions upgrades
Bypass and drain valve attachment
Gear and actuator installation
Nondestructive evaluation (RT, PT & MT)
Casting repair & upgrade
API RP591 qualification testing
Hydrostatic testing
Fugitive emissions testing
Cryogenic testing

A Case History

United Valve performed a modification for an OEM recently which characterizes the modification process very well. After supplying cryogenic valves manufactured to OEM design specifications, it was discovered that the OEM design was not acceptable to the end-user because of some very specific service requirements that went above and beyond the standard product. We then were asked to make the valves conform to the customers needs. This required a new joint design and complete engineering calculations of the new joint assembly. In addition, X-ray radiography procedures needed to be developed to shoot the unusual configuration and yield a readable image.

All of the engineering work was performed in-house and the job proceeded on schedule. The fabrication work met all of the customer inspection requirements and the NDE department performed the radiography to the customer’s satisfaction. The result was that a thorny problem was solved for both the end-user and the OEM, all because a qualified, authorized modification shop was available to perform the work.

OEM Support

OEM support is critical to the success of an authorized modification facility. Since time is of the essence in most modification orders, good communication between engineering departments is a must. A level of trust and confidence must also be built up between the mod shop and OEM in order for the system to function effectively. After a strong relationship has been built, the amount and scope of engineering data provided to the mod shop increases dramatically. But the information stream of valuable information flows back to the OEM as well.

The mod shop is a valuable source of valve quality feedback to the OEM. On the floor of a typical shop, thousands of valves are tested and inspected each year. At United Valve, for example, we have developed an elaborate non-conformance database program that provides very detailed information on every OEM valve failure. This data is then complied and periodically reported back to the OEM for corrective action.

The valve shop also serves as the final inspection point for OEM products. In several cases, defects have been discovered that could have had dire consequences for the manufacturer, had they failed in service.

The question of warranty often comes up when discussing mod shops and OEM’s. Generally, the manufacturer warrants the work that they are responsible for, while the mod shop warrants only the work that they are responsible for. For example, a stem failure on a BWE valve that received only a bore change by the mod shop would be covered by the OEM. However, a poor weld in a weld built-up bore change that failed end-user radiography would be the responsibility of the mod shop. There are also a few OEM’s that state that their warranty covers everything that the authorized shop does to their valves.

Although some manufacturers are now setting up service centers to repair and modify their products, the majority of valve modification work is still performed by independent valve modification shops. The independent shops usually have the edge in service and order turnaround, because they are not encumbered by a large OEM bureaucracy.

Valve modification shops provide an important service to end-users, distributors and OEM’s. The OEM benefits by being able to concentrate on high production items, rather than specials that often slow assembly lines down. The distributor benefits by spending less money stocking slow moving special valves. And the OEM benefits by receiving critical, special valves on-time and at a reasonable price, which lowers his total cost of ownership. The concept of OEM authorized valve modification is a winner for everyone involved!

In the 50’s and 60’s, to be successful in the valve repair business all that was required was some mechanical ability, good people skills and a nice fishing boat or a prolific deer hunting lease. Since then, we have seen the industry morph its way through end-user AML’s, manufacturer’s authorizations, OEM service centers, API Valve Repair Standards, ISO 9000, preventative maintenance and run-to-failure mode. The only constant through it all has been that there are still valves being repaired.

Just like our big brothers in the VMA, the valve manufacturers, our industry is bobbing around on a sea of constant change. Nothing can be taken for granted. Old customers may not be current customers and old ways of doing business just may not be profitable anymore, especially for the shrinking number of independent valve service facilities. As Barry Kemerer, president of Precision Pump and Valveaptly states, “In today’s market, you have to adapt quickly. We used to make money doing business the same way for many years, but not any more”.

Changing Maintenance Philosophy

Of course we are not the only ones dealing with change in a big way. Our customers, the embattled domestic end-users, are squeezed between the rock of a global economy and the hard place of making a profit. As a result, many of the users are looking hard at ways to control costs. And near the top of that list to be controlled are maintenance costs. And as we all know, maintenance dollars are what keeps the valve service industry alive. In the good old days (for valve repair companies) it was preventive maintenance, which was manifested in the scheduled turnaround, where virtually every valve in a unit would be inspected and usually repaired. The winning turnaround bidder could expect one to two weeks of hard, but profitable, blood, sweat and tears. Although the pace was hectic, the valve shop was able to plan for the work and was prepared to handle it.

Today, the buzzword in maintenance circles and throughout most of the industrial world is “Run to Failure” (RTF) mode. Plants are increasingly pressured to get a strong return on their maintenance investment, and RTF has proven in the past several years, to be a good way to help achieve that goal. But this new philosophy presents challenges for the valve shop. “Run to failure mode puts a crimp in scheduling turnaround work. If you can’t schedule, you are in trouble, as far as shop work goes,” says Mike Carbonaro, President of Valve Reconditioning Services. Although RTF reduces the scheduled turnaround shop work, it can create opportunities for more emergency field work, when those valves finally need repair or replacement. Carbonaro adds that “the added aggravation of dealing with run to failure field service work often doesn’t outweigh the extra income of the ‘work-to-completion’, emergency repairs”.

As many valve service companies look for related areas to grow their business, consulting with end-users on valve reliability and maintenance issues is a good potential income target. Predictive maintenance is often used in conjunction with RTF and unlike the control valve, with its smart-valve and field-bus technology, gathering data for the end-user, the vanilla block and check valves are not as adaptable to real-time data technology improvements. Since many critical non-control valves have to be monitored regularly, because failure could be catastrophic for some of them, there are additional opportunities for valve service companies to provide field valve inspection and survey work.

Providing additional services and value-added service, is important in gaining an edge in today’s valve repair market. According to Wayne Kohoutek, President of Midwest Valve, “You have to be an expert in many different areas today- control valves, actuation, PRV’s, metallurgy, engineered valves and more”. Kemerer echoes that opinion, “We are now providing engineering and purchasing support for our customers”. He adds that “sadly, we had one purchasing agent tell us to delete all that extra stuff and just give us your lowest price. Our people should be doing that kind of work anyway”. Unfortunately, many of the end-user engineers are either so-green or so over worked that they don’t have the time or the knowledge to do those “extra” things.

Disappearing End-User Expertise

Another big issue that affects the valve service industry and the valve industry as a whole, is the disappearance of much of the end-user valve expertise. The gold-plated watch syndrome has stripped many of the end-users of their valuable, experienced operations and maintenance personnel. “The maintenance personnel are not the same. They are new guys that don’t have a feel for the historical maintenance or history of the unit”, according to Carbonaro. These “new guys” want to do the right thing, but unless they were well mentored, their decisions, or in some cases their indecision, can cause problems for the valve service company.

This lack of valve knowledge is compounded by the fact that many of the large valve companies have reduced staff, especially in the engineering and research and development departments. This valve knowledge gap is being filled in many cases by the valve service companies, which usually have as much or more practical valve expertise than most of the manufacturers, due to being on the front lines of the valve operation and service wars everyday.

A Different Competitor

In any industry there is always competition. And there has always been ample competition in the valve service arena. But recent business trends have changed the complexion of that competition. “Our competitors today are not the guys (repair shop) down the street, but new valves”, says Kohoutek. The steadily lowering costs of new imported valves, combined with the OEM valve rebuilding programs are causing the valve shops to think out of the box, just to survive. Ten to fifteen years ago, 2” class 150 valves were almost always repaired rather than replaced. Today the cost of a new 2” class 150 gate valve is around $100. Most end-users want to keep repair costs at 50-65% of new for most valves, which equates to $50-65 available to repair the valve.  Most shop rates are around $50/hr, and when added to a base transaction cost, plus new packing, gasket and bolting; a quick inspection, a coat of paint and a hydrostatic test are about all you can do to the valve. Admittedly, 2” valves, which are traditionally the loss leaders of the industry, are probably not a good cost indicator, but the repair costs for other sizes are relatively proportional.

Today’s non-repairable borderline is around 6” for class 150, commodity carbon steel, WCB valves. Some users have raised this replacement-only bar to 12” class 150. As repair shop costs increase and the price of new valves continues to drop, this non-repairable size limit will get larger. Ironically, many of these valves will end up in the scrap heap and will ultimately end up in China, the largest single importer of US scrap, to be made into many products, including new steel valves, which are imported back to the United States!

The rebuilding and selling of rebuilt valves by some OEM’s is also an area of competition for the valve service company. Utilizing their own service center’s capabilities and expertise, they offer their own, as well as other manufacturers rebuilt valves to end users at a substantial savings over new valves. The user then has the choice of a new valve, a factory warranted rebuilt valve or repair of their existing valve. Two out of three of those solutions are not beneficial to the valve repair facility. The choice to repair a valve also may hinge on the availability of OEM parts. “Some manufacturers will sell a factory warranted, rebuilt valve for about the same price they will sell the parts to an independent shop”, according to Kohoutek. That obviously helps sway the customer toward the new or rebuilt valve purchase.

Parts, Always an Issue

The price and availability of OEM parts is always an issue for independent valve shops. “Parts for engineered valves are especially high. The old repair cost formula used to be 75% labor and 25% parts, now it is just the opposite. The manufacturers of these valves want the customer to buy a new one, not repair the old one”, says Kohoutek. “We scrap out some large OD valves simply because the cost of OEM parts is so high”, he adds. However, when you are performing work for an OEM, to help them out of a jam, it is amazing how much support you can get. “The engineering and parts support is outstanding when you are doing an OEM warranty job”, according to Carbonaro.

The teeter-totter of price vs. quality is now firmly tipped to the low-price direction. In most cases today, the customer is asking for cheaper and faster, which puts added pressure on the valve repair companies. “We are being asked to repair valves cheaper than we did 3-4 years ago. Price is the driver now, not quality,” states Kemerer. The drive for lower repair pricing, combined with fewer repair jobs, has made most valve service companies a lot “leaner and meaner”. “Our company is now looking closely at every expense item, both our internal and external costs. Our indirect labor costs have skyrocketed. We are being forced to look at things we used to not look at and operate much more efficiently”, he adds.

Niche markets, value added services and diversity are the “current” keys to success in the valve repair business. “The key to making money in this business is valve mix. There is only so much you can charge to repair a common ANSI gate valve,” according to Kohoutek. Kemerer agrees, “The future of block valve repair is not good”. Many of the shops are looking toward adding lines of new valves to sell. And as more and more manufacturers increase the number of distributorships, in the future some of these may be valve service companies. It is a good fit to have the same company, sell, service (modify & perform warranty work) and repair the product.

What’s next?

Being able to respond quickly to a customer’s needs will be paramount in maintaining excellent customer service, especially for those users which are married to some form of RTF maintenance philosophy. Predictive maintenance data may allow for some degree of shop repair planning, but true RTF events will have to be dealt with swiftly, competitively and competently. Failure to do so will mean the competition (new or factory-rebuilt valves) will get the business. This means that the successful valve repair companies of the future may not look or do business like they do today.

What might the next generation, successful valve service facility look like? First of all it will have to be vertically integrated in order to respond quickly, without being encumbered with outside contractors for items such as machining, welding, heat-treating and basic non-destructive testing. The shop will have expertise, if not experts, in actuation, engineered valves, instrumentation and other related disciplines. It will be the norm to see mechanical and even welding engineers on staff at these companies as well. Everything, from shop-floor management to field service manuals will be readily accessed on computer. All valve repair steps and service records will be traceable via computer data acquisition system and be readily accessible to the customer.

Competent field service work will also have to be offered. Most end-users are reducing the number of valve repair vendors, and companies that can perform both effective field and shop service will have the edge. Needless to say, 24/7 availability will be even more important.

The successful shop will have authorizations from a number of OEM’s and a close relationship with their respective engineering departments. A clear channel for parts and engineering information, not encumbered by sales politics, price-gouging or apathy will be a necessity, because both the OEM and valve service companies reputations (and money) are at stake.

There are still many customers to be served and money to be made in valve repair, even though the rule book is being rewritten every day. It will require shops to look at everything they do and how they do it, and be visionary enough to anticipate and be proactive to industry changes. Costs will have to be strictly monitored. Some customers may even have to be “fired” if it is unprofitable to repair their valves. Kemerer sums it up well by saying, “Shops need to get costs down and work smarter in order to beat the competition. If not, I don’t see how we will be doing what we are doing in five years”.

The first valve patent in America was for a gate valve. It was issued in 1839 to New Haven resident, Charley W. Peckham. Although Mr. Peckham’ s patent was for a sluice gate valve, it was a gate valve nonetheless. It wasn’t until 1840 that the first gate valve as we would recognize it today was patented. It was called a “stop cock” and was issued to Theodore Scowden of Cincinnati, Ohio. Mr. Scowden’s valve was actually a unidirectional gate valve with a primitive bolted bonnet.

The control of steam was the driving force behind virtually every new valve design to come to life from the draughtsman’s table during the period from 1850 through the turn of the 19th Century. This embryonic period for the American valve industry saw many future flow control manufacturing icons get their start: William Teller Crane (Crane); Edmund H. Lunken (Lunkenheimer); William Powell (Powell); H. G. Ludlow (Ludlow); Rufus B. Chapman (Chapman); Charles Jenkins (Jenkins); Daniel Kennedy (Kennedy); and Rufus Pratt (Pratt & Cady). All of these men patented their valve designs and founded companies that would later become well known in the field of flow control.

Other inventors were also striving to improve gate valve design, primarily in the area of disc and seat construction. In 1896, William Jennings, an engineer for the Pratt & Cady Company, patented the screwed-in seat ring design that would remain the standard for the next 75 years, until advancements in welding technology rendered the screwed-in arrangement obsolete.

As the steam power industry matured and boiler temperatures and pressures increased, the valves had to keep up. In some case boiler manufacturers couldn’t get the valves they needed, so they designed and manufactured their own.

Not until the first decades of the 20th century did steam pressures begin to move past the 150-200 psi level. Until then, these low pressure applications were easily handled by the brass and iron valves of the day. Cast iron valves could also easily handle the modest 350-400 degree temperatures in these days prior to high temperature superheaters and steam turbines.

Innovations in the power industry resulted in the rise of operating temperatures and pressures around the 1915-1925 period. This situation fostered the rapid development of a new valve material- steel. Steel could take the pressures and the temperatures that piping in the new central power stations required. During this period of maturation, the steel gate valve adopted the design and appearance that it is still known for today. As operating temperatures and pressures continued to rise, new chrome/moly alloys began to be employed in valve construction.

Powerful new compounds developed by the chemical and petro-chemical industries created corrosion challenges for the valve manufacturers. These challenges were met by a host of new alloys such as Hastelloy, Alloy 20 and Inconel.

The last big advance in gate valve design occurred during the early 1940’s with the invention of the pressure-seal bonnet. The pressure design reduced the mass and weight of large high pressure gate valves by as much as 40%. Pressure seal valves are now the default style of valve for use in power plants.

Since the flurry of pressure-seal patent activity of the 40’s and early 50’s, valve design work has been focused on other types of valves, particularly ball and butterfly valves. As far as design innovation goes, the gate valve may have passed its prime, but its popularity with piping designers, cost-conscious purchasing agents and plant engineers is still very high.

The commodity steel valve industry with its lower profit margins is undergoing a period of significant change as manufacturers struggle to remain competitive. As a result, virtually every major commodity valve manufacturer has turned to countries such as China and India, with their inexpensive labor markets, in an effort to maintain market share. This relocation to new manufacturing sites has made many users uneasy with the potential of poor quality in the valves they purchase.

To confirm the quality and repeatability of these products, many of the major end-users are requiring that the manufacturers qualify their products in accordance with API document, RP591, “User Acceptance of Refinery Valves”. RP591, which is only a recommended practice – not a standard, requires that candidate valves undergo a rigorous series of tests and inspections, including nondestructive evaluations, critical dimension measurements and stem-to-wedge strength tests on gate valves.

The current third edition, with several substantive changes, was approved and published in September of 2003 and published in early 2004. One of the key revisions is that the qualification is now “manufacturing facility specific” instead of brand specific. In other words, the qualification no longer applies just to a manufacturer by name, but also to a specific manufacturing plant and/or foundry.

Just what does API RP591 mean to the end-user and the manufacturer? To the end-user, requiring a manufacturer to undergo RP591 qualification, affords his company some assurance that the advertising and marketing claims of superior quality and API 600 compliance by a valve manufacturer are not just hollow words. To the manufacturer, it is an opportunity to assess the quality, and to a limited sense, the repeatability of their product. If the valves do very well in the testing, there is also the opportunity to help gain a position on a coveted end-user Acceptable Manufacturer List (AML).

RP591 History

To better understand why API RP 591 “Process Valve Qualification Procedure” exists today, we need to look back at the history of the domestic commodity cast steel business over the past 30 years. The story begins with the worldwide petrochemical and refinery construction boom of the mid to late 70’s. While this profitable period was a tremendous economic shot-in-the-bank account for the leading domestic valve manufacturers such as Crane, Powell, Walworth, Lunkenheimer, Jenkins and others, it drastically depleted the commodity steel valve inventory that would normally be consumed for new U.S. construction projects and MRO use.

This situation cracked open an economic door that foreign valve manufacturers had been trying to walk through for many years. Due to acute shortages, domestic manufacturers began bringing in licensed products from Eastern Europe and the Far East. Additional non-affiliated offshore manufacturers also began to make a play on the ripe US market.

Unfortunately, some of the products that were imported did not fare too well in service and a pattern of failures prompted some end-users to address the issue. Here-to-fore, the only testing and inspection that was performed by a user on commodity valves was the cursory API 598 hydrostatic test block. The comfort zone that the over-engineered, rock-solid American valves had provided the industry for over 50 years had now disappeared amidst a rash of leaking castings, stem breakage and seating failures.

In 1979-80, Shell Oil Company became the first refiner to address the qualification testing issue with a fairly thorough test procedure that included a variety of dimensional examinations, operability tests, hydrostatic tests, NDE and chemical analysis of key materials. Through information shared at API Refining Meetings, the major end-users discussed the need for an official valve qualification document. Two men led the valve quality charge in API at that time, Harry Howarth of Mobil and Curt Ball of Exxon.

In 1985, Ball & Howarth presented a draft document to the valve industry that eventually would become the backbone of the API RP591 document. Although it took five years of work group negotiation and open meeting haggling, the first edition of API RP591, “User Acceptance of Refinery Valves”, was published in 1990. The second edition was approved and published in 1995 with only a few changes.

Document Overview

RP591 can be divided into two distinct parts: 1) the manufacturer’s documentation and quality requirements and 2) the actual qualification testing procedure. The first part, which deals primarily with the manufacturer’s quality program, is basically a paraphrase of the 19 tenants of ISO 9001/API Q1.

The actual qualification testing program begins in section 6.0 of the document with requirements for documentation to be provided by the manufacturer to the testing agency and included in the test report. This data includes drawings, requested welding procedures, casting and/or forging source information, closure torques, rim pull calculations, and the location of final assembly and testing of the valves.

The first requirement for the manufacturer is to select a mutually acceptable testing facility to perform the inspection. To be eligible for consideration as an API RP591 testing facility, the lab must have a degreed mechanical or metallurgical engineer on staff overseeing the testing.

The inspection process begins with the testing facility randomly selecting valves from an inventory of like valves in pressure class, material and size from manufacturer or distributor stock. The valves are then tagged and heat and serial numbers are recorded. They are then shipped to the testing facility for the actual inspection process.

Prior to disassembly the valves are subjected to hydrostatic pressure tests in accordance with API 598. All optional API 598 closure tests are performed as well. For all seat tests, the recommended closure torque values provided by the manufacturer are used, and the actual closure torques are measured via a calibrated torque wrench. A device to connect the torque wrench is attached to the center of the stem shaft or gear operator. If the torque recommended by the manufacturer is inadequate to prevent leakage, the torque may be increased by a maximum of 25%. All valves are tested in the stem horizontal position.

Visual Inspection & Material Tests

Following hydrotesting, the visual inspection process is begun. After as-assembled dimensions are recorded, the valves are disassembled for detailed component inspection. Over 40 different items are visually inspected and/or measured. The visual inspection includes everything from handwheel construction to stem cylindricity and straightness.

After all the measurements have been taken and conditions recorded, paint and sealants are removed from the body, bonnet and covers (as applicable) and the castings are visually inspected per MSS SP55. Forgings are inspected to confirm they are free of laps and seams.

A key requirement of RP 591 is chemical analysis and hardness testing of all key components on a minimum of five sample valves.

To confirm that valve handwheels are in conformance with API 600 and will not fail during the rigors of severe field use, two tests are performed. The first test involves striking the handwheel between spokes with a 3 lb. or 10 lb. hammer, depending upon valve NPS. The second test requires the wheel to be subjected to a torque test at 300% of the manufacturers design torque. Any damage is to be reported.

Stem Shaft/Closure Element Strength Test

One of the prime motivators for the creation of RP 591 30 years ago was a series of stem to wedge failures encountered by several end-users. The “Stem Pull Test” as it is generally called, is performed on a tensile test machine. The Closure member and stem are both held in special fixtures to enable them to be properly gripped by the tensile test machine. The stem is then “pulled” and the actual load and point of failure is recorded. The manufacturer is required to provide expected stem shaft to closure element failure calculations to the testing facility, so that the fixtures may be properly designed and built.

The goal of the stem pull test is to insure that the first point of failure in a stem to closure element break occurs outside the body of the valve. Because an outside-the-pressure-containing-area failure provides the valve owner a section of stem to grab in case emergency opening procedures are required following a stem to closure element failure. Failure inside the pressure containment area means that the line will have to be de-energized and the valve disassembled for stem removal and disc opening. The stem pull is also the most exciting part of any RP591 test, especially when a large diameter stem snaps apart in the tensile machine!

Nondestructive Evaluation (NDE)

The most telling aspect of the RP 591 inspection process has to be the NDE phase, particularly the radiography. All accessible pressure containing welds are radiographed in accordance with table 341.3.2 of ASME B31.3, using the acceptance criteria for normal fluid service conditions. Pressure containing welds that cannot be radiographed are examined by either magnetic particle or liquid penetrant in accordance with ASME B16.34. Sections of cast valves, as identified in B16.34, from four valves or 25% of the sample lot (whichever is larger) are examined by radiography in accordance with B16.34 as well. Details of any discontinuity as well as sketches illustrating the film locations are included in the report.

One of the key revisions in the 3rd edition of RP 591 is the requirement that changes in sources of pressure-containing forgings or castings require that additional testing (generally radiography) be performed. Items that require complete requalification of a valve include “any design change that will reduce the strength or impair operability of the valve or a change in location of manufacture”.

What RP 591 Doesn’t Require

While RP 591 is an extensive document, there are additional tests that are not found within its pages. The issue of fugitive emissions is not addressed and many end-users will request that some form of fugitive emissions testing be performed in conjunction with the 591 testing program. Some users also require a submerged helium shell test to further insure casting quality. As far as metallurgical examinations go, detailed testing of castings is not required. However, some users who have experienced casting imperfections are requiring metallographic examination of castings, as well as other more thorough metallurgical examinations plus additional radiography.

Also absent from the 591 document is a requirement for testing valves in different positions, such as the stem horizontal with horizontal flow configuration, to determine that the valve operates in all positions. This multi-directional test requirement was a part of some users testing requirements prior to the publication of RP 591.

Conclusions

RP 591 testing is not cheap for the manufacturer. However the economic benefits of gaining a spot on an active AML can be great. Even if the testing reveals inadequacies, this data can help the manufacturer to improve their product, by pointing out specific areas of needed improvement, which can translate to more satisfied customers and greater sales.

API RP 591 is an excellent tool to determine a”snapshot” view of a manufacturer’s valve quality. Users should also maintain a record of valve performance gathered from their own in-service observations as well as information provided from their valve repair and modification contractor(s). This valuable data can help insure that the RP 591 qualified valves are maintaining their pedigree.

Almost every major commodity valve manufacturer has moved their production location during the past three years, or is considering doing so in the next 12 months. The economics of a global economy are demanding it. These changes mean that past performance data cannot necessarily be counted on to confirm current valve quality. This makes the time and effort of implementing some form of examination program, such as RP 591 testing, a worthwhile endeavor that could potentially save lives and property.

“Testing, testing, 1 2 3…” We’ve all heard those words before as some nervous master-of-ceremonies tries to test the performance of the sound system over the tinkle of glass and the low roar of the after-dinner crowd. Wouldn’t life in the valve world be a whole lot easier if we could just utter a few words and become instantly convinced as to the quality and performance of our valves?

Today, more than ever before, testing is extremely important in the valve industry. The increase in globally sourced products and much-reduced domestic manufacturing has caused everyone in the valve supply chain to request and require more testing.

In order to effectively test a valve, there first must be an established testing procedure, combined with the acceptance criteria or performance standards that the valve is expected to meet or exceed. When it comes to testing standards though, one size does not fit all. There are different standards for bronze valves, steel gate valves, iron valves, pipeline valves, control valves and pressure-relief valves.

Up until about 1968, the acceptance criteria for most valve types were pretty simple: They weren’t expected to leak during testing. The most common valve design standard for the past 50 years has been the American Petroleum Institute (API) valve standard for refinery use, known today as API 600, “Bolted Bonnet Steel Gate Valves for Petroleum & Natural Gas Industries.” For 20 years, the document also contained valve testing criteria, and that criteria was pretty tough: “Valves shall show no leakage when subjected to a hydrostatic (or air) seat test.”

Today, most valve manufacturers strive for and achieve a zero closure test leakage rate during initial factory testing of their metal seated gate and globe valves. However, the predominant valve testing standard, API 598, “Valve Inspection and Test,” does have allowable leakage rates for these types of valves in sizes above NPS 2. Virtually all test specifications for resilient-seated valves require they exhibit zero leakage during the test period.

Determining Test Pressures

The first order of business in valve testing is determining the pressures at which the tests are to be performed. Many standards, such as API 598, do not list detailed pressures, only the procedure for testing. The actual test pressures are derived from pressure ratings that have been developed based on the materials of construction and design criteria, such as wall thickness.

In the early days of valve manufacturing, only two common valve materials were available, cast iron and bronze, and three pressure ratings: standard, medium and extra heavy. There was also no common definition of any of these ratings. Catalogs often described the factory tests and in some cases included the actual bursting pressure, so users could assign whatever working pressure and safety factor they wished.

Around 1930, the American Standards Association (ASA), in its B16e document, “Flanged and Welding-End Steel Wedge Gate and Plug Valves for Refinery Use,” created a common set of pressure ratings for the various valve classes we know today—class 150, class 600, etc… Except for class 150, all of the ratings were based on the class number’s pressure rating at 750o F steam. Class 150 for some reason was based on steam at only 500o F steam.

Figure 1—Original ASA pressure temperature ratings

The successor to B16e was the currently in-use standard by the American Society of Mechanical Engineers, ASME B16.34, “Valves-Flanged, Threaded, and Welding End.” B16.34 is the mother document from which many testing specifications establish their baseline test pressures. The ASME document specifies the working pressure for the established pressure classes in a vast range of materials from low-carbon steel to exotic alloys. From this working pressure—for example, 285 psi for WCB, class 150 valves—the test pressures are derived.

If we were using API 598 as our testing standard, the 285 psi class 150 working pressure would become 325 psi for the backseat and high-pressure closure test (285 x 1.1) and 450 psi for the shell test (285 x 1.5). The actual results are rounded up to the next 25 psi point. ASME B16.34 does contain a testing procedure; however, its closure test protocol contains no acceptance criteria as that data is deemed “out of the scope of the document.”

International Standards

The U.S. valve industry’s shift to a more global posture, combined with the huge increase in foreign valve manufacturers, has put increasing focus on international valve standards. The primary International Organization of Standardization (ISO) valve standard is ISO 5208, “Industrial Valves – Pressure Testing of Valves.” The standard is similar to the API 598 document, but recent updates have separated it more and more from the U.S.-developed standard. One of the key differences between ISO 5208 and API 598 is that the ISO document has a choice of four leakage rates, from gross leakage to zero. The ISO document also widens the users vocabulary by one word—“obturator.” An obturator is the closure element of a valve and in the ISO document it replaces the term disc or wedge.

Another difference in many ISO valve standards is that they also include testing criteria within their base design document. This has not been the case for the past 40 years for most steel and alloy valves in the United States. However, there is more and more talk at standards development meetings about adding test criteria to design specifications, such as many of the API valve standards.

While steel valve specifications such as API 600 have yet to be augmented with testing criteria, there are several U.S. valve standards that do have self-contained testing procedures. These are primarily iron and bronze valve standards and are covered by a host of Manufacturers Standardization Society (MSS) documents.

Special Valves, Special Tests

Control and pressure relief valves (PRV) are special purpose valve types and it follows suit their test procedures are unique as well. The primary goal of PRV testing is to confirm that the valve will both lift (open) at the correct pressure and provide the prescribed rate of flow. A control valve is normally tested to measure its rate of flow as well. Both PRVs and control valves are also tested to confirm the integrity of their pressure envelope.

PRVs are tested in accordance with two primary standards: ASME PTC 25, “Pressure Relief Devices” and API 527, “Seat Tightness of Pressure Relief Valves.” The common testing standards for control valves are ISA—the Instrumentation, Systems and Automation Society of America ISA-S75.19 and Fluid Controls Institute (FCI) FCI 70-2, “Control Valve Seat Leakage.”

The upstream pipeline and petroleum valve industry also have their own testing specification. It is located within the pages of the API 6D, “Pipeline Valves” valve design document. API 6D leakage rates are very close to those of API 598, but its holding times are longer.

Increasingly stringent clean air regulations have created the need for a new type of valve test, the fugitive emissions (FE) test. In FE testing, the goal is to determine the degree of minute leakage, if any, from the packing and gasket areas. The test requires pressurization of the pressure envelope with either methane or helium. Then the sealed valve is inspected with a sniffer device that measures any leakage in parts per million. The goal of most FE testing is to confirm that leakage rates are lower than 100 ppm or in some cases 50 ppm. The most common FE testing standards are ISO 15848, “Industrial Valves, Fugitive Emissions – Measurement, Test and Qualification Procedures” and API RP622, “Type Testing of Process Valve Packing for Fugitive Emissions,” although specific end-user standards are also very prevalent.

Nearly all valve test standards are designed to test valves at ambient temperatures, generally from 60° F to 120° F. But what about valves designed for low-temperature operation, such as liquid natural gas (LNG) or gas separation service? These cryogenic valves have their own testing standards, the most widely used being the British Standard Institution’s BS6364, “Valves for Cryogenic Service.” MSS has also developed a cryogenic standard that contains test criteria, SP-134, “Valves for Cryogenic Service, including Requirements for Body/Bonnet Extensions.” A third cryogenic testing standard is currently under development by an ISO work group.

Figure 2—Common valve types and their related test standards

*Test requirements contained within design standard

Key Valve Testing Standards

Here is a summary of some of the most common valve testing standards:

API 598, “Valve Inspection and Test” – The most widely used test specification in the world today. The document covers all types of valves in sizes through NPS 24. It also includes leakage rates and testing criteria for metal-seated and resilient-seated valves.

API 527, “Seat Tightness of Pressure Relief Valves” – This document covers the seat tightness of pressure relief valves. It also includes allowable leakage rates for testing with steam, water and air.

ASME B16.34, “Valves – Flanged, Threaded and Welding End” – The primary valve design document, it also contains charts for determining the working pressures of valves to be used in conjunction with other test standards, such as API 598. B16.34 contains a test procedure, but no seat leakage acceptance criteria.

ASME PTC 25, “Pressure Relief Devices” – The main reference document for the testing of pressure relief valves, PTC 25 contains detailed procedures for testing relief valves with air or steam.

FCI 70-2, “Control Valve Seat Leakage” – This document contains detailed test procedures and leakage rate classes for control valves. The leakage classes are also occasionally referenced by other documents and used as acceptance criteria.

ISA-S75, “Hydrostatic Testing of Control Valves” – It provides a procedure for the hydrostatic shell testing of control valves. Closure testing and acceptance criteria are out of the scope of this document and usually are covered by referencing FCI 70-2.

ISO 5208, “Industrial Valves, Pressure Testing of Valves” – ISO’s primary testing standard, this document covers all types of valves and has four levels of allowable closure test leakage.

MSS SP61, “Hydrostatic Testing of Steel Valves” – Similar to API 598, this document has some subtle differences in test holding times and leakage rates.

MSS SP70, “Cast Iron Gate Valves, Flanged and Threaded Ends”– The primary design document for cast iron gate valves, it also contains testing procedures and acceptance criteria.

MSS SP71, “Cast Iron Swing Check Valves, Flanged and Threaded Ends” – The primary design document for cast iron check valves also contains testing procedures and acceptance criteria.

MSS SP78, “Cast Iron Plug Valves, Flanged and Threaded End” – The primary design document for cast iron plug valves also contains testing procedures and acceptance criteria.

MSS SP80, “Bronze Gate, Globe, Angle and Check Valves” – The primary design document for commodity bronze valves also contains testing procedures and acceptance criteria.

MSS SP85, “Cast Iron Globe & Angle Valves” – The primary design document for cast iron globe valves also contains testing procedures and acceptance criteria.

What Lies Ahead?

What does the future hold for valve testing standards? As mentioned earlier, there is a trend in some standards-creating bodies to include the testing specifications within the primary design document, and we may see more of that practice sooner rather than later. The fugitive emissions issue could also foster the creation of a user friendly, production-type FE valve test method. The current FE testing protocols are primary design or prototype verification procedures and not easily adapted to production testing usage.

Valve testing techniques have changed over the years and at the same time test procedures have become more thorough. But one thing is for certain: As long as men and women, or automated robots for that matter, are building valves, there will always be a need for valve testing and effective testing standards to govern those tests.

Where On The Web

• American Petroleum Institute – www.api.org
• American Standards Association – www.ansi.org
• American Society of Mechanical Engineers – www.asme.org
• British Standards Institution – www.bsi-global.com
• Fluid Controls Institute – www.fluidcontrolsinstitute.org
• International Organization for Standardization – www.iso.org
• ISA (Instrumentation, Systems and Automation Society of America) – www.isa.org
• Manufacturers Standardization Society of the Valve and Fittings Industry – www.mss-hq.com