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Maintenance & Repair

Just Read the Instructions

Although the situation might change eventually, it’s a reality that most people working in the valve repair industry today are men. It is also a reality that many men hate to read instructions or rely on a map. However, when repairing critical pressure-containing equipment such as valves, a little glance at the words now and then can be important. And when it comes to valve repair instructions and standards, sometimes it takes a little digging to find the right paragraphs of wisdom.


For commodity valve repair, a thorough repair document is published by the American Petroleum Institute (API) entitled API Recommended Practice (RP) 621, “Reconditioning of Metallic Gate, Globe, and Check Valves.” RP621 is a 15-year-old document created by a joint team of valve repair companies and end-users to standardize the process of valve repair. Prior to RP621, commodity valve repair standards were created and maintained by each individual end-user as well as many repair facilities themselves. This consolidation of valve repair standards has helped to create a level playing field.

The detailed procedures and standards found in RP621 are designed for gate, globe and check valves, but many of the principles are easily adaptable to other valve types. If RP621 has a drawback, it is that repairing valves in accordance with its requirements is relatively expensive. Because inexpensive import cast steel valves have emerged, repairing smaller sizes to any standard, much less RP621, is not feasible. However, the repair of larger, higher pressure and critical application valves—such as those in the American Society of Mechanical Engineers (ASME) B31.3, category M Lethal Service—under the RP621 standard, is still cost effective. Even if all the tenets of the standard are not followed, enough good information exists to create a less detailed, but relevant valve repair procedure. RP621 can also be used as a starting point for creating valve repair procedures for other valve types.

API has another repair document for upstream valves, API 6DR, “Repair and Remanufacture of Pipeline Valves.” The 6DR document is not as extensive as RP621, but it does outline the major requirements of pipeline valve repair.

Both API RP621 and 6DR require the repair practitioner to possess current editions of the parent documents under which the valves were originally manufactured. For API RP621, those documents are: API 600, “Steel Gate Valves—Flanged and Butt-welding Ends, Bolted Bonnets”; API 602, “Steel Gate, Globe and Check Valves for Sizes NPS 4 (DN 100) and Smaller for the Petroleum and Natural Gas Industries”; API 603, “Corrosion-resistant, Bolted Bonnet Gate Valves—Flanged and Buttwelding Ends”; and API 594, “Check Valves: Flanged, Lug, Wafer and Butt-welding.”  For the API 6DR standard, the parent document is API 6D, “Pipeline Valves.” In addition to these parent documents, any facility performing repairs on these types of valves should have copies of the referenced ASME, Manufacturers Standardization Society and American Society for Testing and Materials (ASTM) documents as well.

Instructions for pressure relief and safety valves are provided in publications produced by the National Board of Boiler and Pressure Vessel Inspectors. The “National Board,” as it is referred to, publishes detailed procedures and standards for repairing and inspecting pressure relief valves (PRVs). Because of the essential safety-related nature of these valves, repair procedures are critical and must be followed closely. To even begin the process of PRV repair, a facility must first be audited by the National Board and then receive repair certification for their operation.

Currently, no published control valve repair standards exist. However, parent documents are published by the Instrument Society of America and associated reference documents are published by both ASTM and ASME.

To summarize, valuable reference standards are available that can closely guide valve repair operations or at least give some general guidance. However, as far as the problem with males not reading instructions, the only real solution may be to hire more women!

Greg Johnson, a contributing editor to Valve Magazine, is president of United Valve (www.unitedvalve.com), Houston, TX. Reach him at This email address is being protected from spambots. You need JavaScript enabled to view it..

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