|
|
API RP 621
 API Recommended Practice 621, "Reconditioning of
Metallic Gate, Globe and Check Valves"
In 2001, after several years of discussions and meetings, The American Petroleum
Institute (API) Refining Committee published a common valve reconditioning
standard. The standard was conceived to eliminate the vast number of similar,
yet not quite the same, valve repair standards that each end-user had. The new
standard is more stringent than most end-user repair documents, and it is also
more stringent than most valve shops are used to working with. However, the end
result will be higher quality reconditioned valves for all the end-users that
adopt the standard and for all the shops that adhere to its requirements.
RP 621 is available from Global Engineering Documents,
http://global.ihs.com, for $95.00.
RP 621 SCOPE
1. This Recommended Practice (RP) provides guidelines for reconditioning heavy
wall (API 600 type) carbon steel, ferritic alloy (up to 9% Cr), stainless steel,
and nickel alloy gate, globe, and check valves for ASME pressure classes 150,
300, 400, 600, 900, 1500, and 2500. Guidelines contained in this RP apply to
flanged and butt weld cast or forged valves.
 2. It is an expectation of this Recommended
Practice that a contractual agreement shall be established between the owner and
the valve reconditioning facility. The reconditioning facility may be OEM
owned/operated, or directly associated and approved by the OEM. At the owner's
option, an independent facility may be used. The owner shall determine that the
facility selected for valve reconditioning has a documented and established
working Quality Assurance Program. The Quality Assurance Program should include
the essential elements described in Section 7 of API RP 591 or follow the
principles of an appropriate standard from the ISO 9000 Series.
3. This RP does not cover reconditioning or
re-manufacturing 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. Valves reconditioned or
re-manufactured to this RP may not meet API Standard requirements for new
valves. The correct application of a valve reconditioned to this Practice
remains the responsibility of the owner.
API Recommended Practice 621 Reconditioning of Metallic Gate, Globe and Check
Valves
Table of Contents
|
1. |
General |
|
1.1 |
Scope |
|
1.2 |
References |
|
1.3 |
Owner Access |
|
2. |
Purchaser Responsibilities |
|
2.1 |
Valve Information |
|
2.2 |
Material Safety Data Sheet |
|
2.3 |
Preparation for Shipment to Reconditioner
|
|
3. |
Inspection, Identification, and Disassembly of Valves
|
|
3.1 |
General |
|
3.2 |
Identification Number |
|
3.3 |
Traveler Documents |
|
3.4 |
Disassembly and Cleaning of Valves |
|
4. |
Repair of Valve Parts |
|
4.1 |
General |
|
4.2 |
Inspection of Valve Components |
|
4.3 |
Handwheel Nut |
|
4.4 |
Handwheel |
|
4.5 |
Yoke |
|
4.6 |
Stem Nut and Stem Nut Housing |
|
4.7 |
Stem Nut Retainer |
|
4.8 |
Packing Gland Flange |
|
4.9 |
Packing Gland |
|
4.10 |
Back Seat Bushing |
|
4.11 |
Body and Bonnet |
|
4.12 |
Body Guides |
|
4.13 |
Body Seat Ring(s) |
|
4.14 |
Wedge Guides |
|
4.15 |
Wedge, Globe, and Clapper |
|
4.16 |
Stem |
|
4.17 |
Body to Bonnet Joint Bolting |
|
4.18 |
Packing Gland Eye Bolts |
|
4.19 |
Packing |
|
4.20 |
Body to Bonnet Joint Gasket |
|
5. |
Post Repair Assembly |
|
6. |
Pressure Test |
|
7. |
Preparation for Shipment |
|
8. |
Tagging and Reconditioning Facility Identification
|
|
Appendix 1 |
Stem Packing |
|
Appendix 2 |
Weld Overlay of Stems |
|
Appendix 3 |
Tests |
|
Table 1 |
Minimum Thickness of Shell Wall and Minimum Diameter of Stem, in
Inches |
|
Table 2 |
Allowable Pitting and Localized Corrosion |
|
Table 3 |
Gasket Material and Surface Finish |
|
Figure 1 |
Flexible Graphite Packing for Block Valves
|
|
Figure 2 |
PTFE Vee Ring Packing for Block Valves
|
|
Figure 3 |
Lattice Braid PTFE Filament Packing for Block Valves
|
|
Figure 4 |
Required Stuffing Box Clearances |
|
