Safety Valve Repaired by an Unaccredited Shop and Set Above MAWP
A 150-psig steam boiler in a food plant has two safety valves. The No. 1 valve is set at 150 psig and has a current capacity certification. The No. 2 valve was repaired last month by a local machine shop that holds no National Board accreditation. The shop replaced the spring, lapped the seat, and attached a tag stamped 'VR' with the shop's initials. The valve is now set at 165 psig and is installed on the boiler. The boiler's MAWP is 150 psig. The plant operator says the second valve is only a spare and that the first valve is enough. The jurisdiction requires safety valves to be repaired by a VR-stamp holder and set at or below MAWP. The inspector must decide whether the boiler can operate and what to do with the valve.
1. Can the boiler operate with the No. 2 valve as installed? Consider both set pressure and repair accreditation.
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No. The No. 2 valve is set at 165 psig on a 150-psig MAWP boiler, so it would not provide protection at or below the MAWP; a safety valve set above MAWP is not acceptable. In addition, the repair was made by a shop without National Board VR accreditation, and the 'VR' tag is not valid. A valve repaired by an unaccredited shop cannot be treated as a code valve merely because it has a tag. The operator's claim that it is 'only a spare' does not help while it is installed: an installed safety valve must be correct. The inspector should require the valve removed from service and either replaced or repaired by a VR-stamp holder and set at or below 150 psig. Before allowing operation on the remaining valve, the inspector must verify that its capacity is sufficient for the boiler; if not, the boiler cannot operate.
2. What does a legitimate VR stamp require, and what records should the inspector see?
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A VR stamp is a National Board accreditation mark for repair of pressure relief valves. The holder should have an accepted quality control manual, qualified personnel, proper test equipment, and a system for controlling parts and settings. The repaired valve should be tested and set, sealed, and documented on a valve repair report (VR-1). The inspector should verify the stamp and accreditation, the set-pressure test record, the capacity certification if applicable, and the seal. A shop's initials and a homemade 'VR' tag are not evidence. The inspector should also check that the valve's set pressure does not exceed the boiler MAWP and that the valve is the correct type for steam service.
3. What should the inspector do if the owner insists on running with only the No. 1 valve?
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The inspector should not accept the owner's assurance. The remaining valve must be shown to have enough relieving capacity for the boiler's maximum output; if it does not, the boiler must be taken out of service until a compliant second valve is installed or the remaining capacity is proven. The inspector should document the nonconforming valve, the capacity calculation, and the owner's decision. If the owner operates anyway, the inspector should notify the jurisdiction and recommend certificate action. The inspector's role is to verify code compliance, not to negotiate a temporary waiver without jurisdiction approval.