VALVE MAGAZINE Winter 2024

VALVE BASICS

Photo Credit: United Valve

10.2.2 Valves shall be disassembled in accordance with Sections 4.1 and 4.2. 10.2.3 All paint is removed from valve body and bonnet, either by abrasive means (grit or shot blast) or with chemical paint stripper. 10.2.4 All exterior areas as well as accessible interior areas of the body and bonnet are to be examined. 10.2.5 PT inspection is to be performed by personnel certified to Level II, in accordance with ASNT (American Society For Nondestructive Testing) SNT-TC-1A. Level I personnel may perform the inspection under the guidance of an onsite Level II inspector. 10.2.6 PT inspection shall follow the guidelines of MSS SP-93 or ASME B16.34, Appendix III. Acceptance criteria shall be in accordance with the re s p e c ti ve te s t s p e c i fi c ati o n . While the MSS standards are helpful, it is important to remember that this is new valve modification, which means that the original design standards must be maintained unless superseded by an owner/end user’s specific request for variance. When performing modifi cation work, it is imperative that an inventory of current valve design standards, such as ASME B16.34, American Petroleum Institute (API) 600 or API 594 be maintained. Additionally, a modifier is responsible for any necessary design calculations, such as those needed for substi tuting a stronger stem material for a weaker material (e.g., 410ss to 316ss). Bonnet extensions for cryogenic applications or extension tubes for buried pipeline service also require competent design work. OEM SUPPORT IS VITAL Modification shops are 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.

These secondary inspections can provide valuable data to the OEM if nonconformances are found. The valve shop also serves as a second “final inspection point” for OEM products. Defects have been discovered by modification facilities that could have had dire conse quences for the manufacturer had they failed in service. THE WARRANTY Although some manufacturers have set up service centers to repair and modify their products, the majority of valve modification work is still performed by independent valve modification shops. These independent shops usually have an edge in service and order turnaround because they are not encumbered by a large OEM bureaucracy that rightly prefers mass production of new valves over specialized valves. Valve modification facilities provide an important service to end users, distributors and OEMs. The OEM benefits by being able to concentrate on high produc tion items, rather than late-ordered specials that often slow assembly lines down. The distributor benefits by spending less money stocking slow-moving special valves. The end user benefits by receiving critical, special valves on time and at a reasonable price, which lowers total cost of ownership.

ABOUT THE AUTHOR

Greg Johnson is president of United Valve. He is a member of the Valve Editorial Advisory Board, a founding member of the VMA Education and Training Committee and past president of MSS.

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VALVE MAGAZINE

WINTER 2024