Depending on equipment age, repair history, application severity and other factors, salvaged/refurbished (aka “remanufactured”) or repaired control valves may no longer meet a manufacturer’s original specifications as designed in accordance with the ANSI/ASME B16.34 control valve standard, “Valves – Flanged, Threaded, and Welding End”.(1)
This is the only available ANSI/ASME standard currently written for control valves; however its scope covers “new” valves. Thus, in the absence of a Standard for “used” control valves (i.e. to include salvaged/refurbished, remanufactured, or repaired) the issue of ensuring sustained integrity, through valve refurbishment to the manufacturer’s design specifications as developed in accordance with the ASME standard, may be overlooked.
Control valve damage resulting from severe service applications is typically recognized by visual inspection and corrective action (assuming such repair actions appropriately return the valve to its original design specifications and dimensions as covered in the remainder of this article). However, there are many process applications where gradual degradation of control valve surfaces or thickness may not be noticeably visible, possibly resulting in potential integrity failure (loss of containment) with potential injury or property damage.
So the questions that beg answering for “used” equipment such as salvaged, remanufactured, or repaired control valves are:
- “When new chemical plant and refinery projects require adherence to a control valve design standard such as ASME B16.34 to better ensure plant design safety and address regulatory requirements, then why wouldn’t periodic inspection with adherence to the same standard be required during the operational life of a control valve?
- Is the process industry requiring inspection, verification and certified documentation of control valve design parameters that are critical for integrity and meeting piping system pressure class, specifically including certification of body wall thickness?
Standards have been developed to address these types of issues for the repair and refurbishment of “used” pressure vessels. Such is not the case for control valves; however there are methods available to help upstream and downstream process industry end users manage their control valves to:
- Reduce risks associated with loss of containment
- Address the mechanical integrity element of the PSM Standard(2) and RMP Rule(3)
- Simultaneously increase reliability and uptime
- Minimize internal resource demand by using supplier capabilities