API Recommended Practice 591, “User Acceptance of
Refinery Valves”, provides end-users or other interested parties testing
procedures and acceptance criteria for evaluating a manufacturer’s valves.
United Valve performs RP 591 testing for both end-users and manufacturers. Our
integrated NDE capabilities, along with decades of valve experience, give us the
ability to verify quality and find problems or idiosyncrasies with a particular
valve design.
The basic test procedure requires that a number of valves be randomly selected
from a distributor or manufacturer’s stock. First the valves are pressure tested
in accordance with API 598 or other applicable test document. Next, the valves
are subjected to an extensive visual and dimensional inspection, followed by
radiography of the castings. Chemical analysis and hardness tests are also
performed on several critical components.
The most critical inspection for gate, ball, plug and butterfly valves is the
stem to ball/wedge/plug tensile test. This test is designed to determine the
first point of failure between the shaft and the closure member. To meet the
requirements of RP 591, the first point of failure must occur outside the valve
pressure boundary.
United Valve is certified by major refiners to perform RP591 testing. The test
results are used to help determine possible inclusion on their acceptable
manufacturers list (AML).
API Recommended Practice 591, “User Acceptance of
Refinery Valves”, provides end-users or other interested parties testing
procedures and acceptance criteria for evaluating a manufacturer’s valves.
United Valve performs RP 591 testing for both end-users and manufacturers. Our
integrated NDE capabilities, along with decades of valve experience, give us the
ability to verify quality and find problems or idiosyncrasies with a particular
valve design.
The most critical inspection for gate, ball, plug and butterfly valves is the
stem to ball/wedge/plug tensile test. This test is designed to determine the
first point of failure between the shaft and the closure member. To meet the
requirements of RP 591, the first point of failure must occur outside the valve
pressure boundary.