Issues regarding maintenance strategies for process valves
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I have a question regarding the maintenance of valves used in major overhauls: whether to replace a process valve or repair it. How is this decision generally made? Are there any standards or strategies for this purpose, and how is it determined when a process valve should be discarded?
The last edit to this post was made by Shutong on 2022-4-19 at 20:51. To determine whether a valve needs repair or replacement, one should first identify the appropriate standards based on the type of valve. After the valve is taken out of service, its casing, sealing performance, and other technical specifications should be examined before making a decision.
Generally, first check whether the valve in need of repair is worth fixing; if the cost of repair exceeds the cost of purchasing a new valve, it is not necessary to carry out the repair. Additionally, the valve to be repaired is disassembled to check whether any of its main components are missing, or whether the damage to these components is severe enough to allow for the creation of new drawings ； Another point is whether the wall thickness of the pressure-bearing parts of the valve housing or valve cover, or the flanges, meets the current relevant standards. Lastly, during maintenance, it’s important to consider the procedures related to welding and heat treatment processes, to ensure that the quality of the repairs is satisfactory; ultimately, it still depends on the user’s opinions. Personal opinion, for reference only
The maintenance and replacement of valves in petrochemical enterprises involve various factors. This includes the importance of the valve, whether it needs repair and whether it is imported (whether domestic valves are worth repairing), the extent of damage to the valve and the costs associated with repairs, as well as the inventory levels of valves and the lead time for procurement. Equipment managers need to take all the relevant factors mentioned above into consideration comprehensively.
You can take a look at the specific documents that provide support for what you want to know. SH 3518: Regulations for the Inspection and Management of Petrochemical Valves; SH 3064: Selection, Inspection, and Acceptance of General Steel Valves Used in Petrochemical Applications. The two standards for the petrochemical industry are quite good and practical.