Repair or replace a gate valve: how to decide
A passing gate valve is common. Sometimes new packing or a lapped seat is enough; sometimes repair costs more than a new valve. Here is how to compare.
TAZ Engineering Team · · 5 min
When repair makes sense
Leaking gland: repack in place. Stiff operation: clean and grease the stem, replace the stem nut. Minor seat leakage on a large steel gate valve: lap or hardface the seats in a workshop. Repair pays off for expensive large-bore and high-rating valves.
When to replace
Cracked or deeply corroded body, worn stem thread, failed rubber-encapsulated wedge, no spares for an old model. For small and medium cast iron gate valves a new valve is usually cheaper than removing, repairing and reinstalling the old one.
Count the full cost
Add labour, customer outage, transport to the workshop, testing and the risk of repeat failure. A repaired valve must pass the same shell and seat tests as a new one.
Like-for-like replacement
To avoid modifying the pipe, choose the new valve with the same face-to-face length and end connection. Send the old valve’s designation or measure the length between flanges and TAZ will find an equivalent.
Checklist
- defect type
- material and DN
- spares availability
- downtime cost
- testing after repair
- face-to-face length for replacement