Bypassed Low-Water Cutoff and Tube-Sheet Grooving on a Hospital-Laundry Boiler
During the required annual internal inspection of a 200-hp, 150-psig saturated-steam firetube boiler at a commercial laundry, the commissioned inspector finds two problems. The low-water fuel cutoff has been bypassed with a jumper wire across its switch terminals; the boiler is currently steaming and the bypass is not tagged. In addition, the rear tube sheet has a circumferential groove about 3/8 in. wide at the ligament between two tube holes; the groove is visible but the inspector has not yet measured its depth. The boiler holds a current certificate of inspection that expires in 30 days, and the plant manager wants to defer any shutdown to the next planned outage in six weeks because the laundry serves a hospital. The jurisdiction has adopted NBIC Part 2 for in-service boilers and requires an annual internal inspection. The inspector must decide what can remain in service, what must be corrected now, and how to document the findings.
1. What must the inspector do about the bypassed low-water fuel cutoff before the boiler can continue in service, and does the unexpired certificate change that answer?
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The bypass is an imminent hazard and a code violation. The low-water fuel cutoff is a required safety control on a steam boiler; a jumper wire defeats both the cutoff and its burner interlock. The inspector should require the jumper removed immediately, the control restored, and the low-water cutoff tested by evaporation or simulated float drop while the burner is firing. If it cannot be restored and proven, the boiler must be taken out of service. The certificate of inspection does not authorize operation with a defeated safety device; it is evidence of past inspection, not a permit to run unsafe equipment. The inspector should notify the owner in writing and the jurisdiction as required, and record the finding and correction. Only after the control is restored and tested can the boiler remain in service while the tube sheet is evaluated. If the owner refuses, the inspector should recommend suspension of the certificate and document the refusal.
2. How should the inspector evaluate and disposition the tube-sheet groove?
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The width alone is not the acceptance criterion. The inspector should clean the area, measure the groove depth and remaining ligament, and compare it with the original code minimum thickness and any applicable NBIC Part 2 evaluation criteria. A groove at a tube-hole ligament reduces the load-bearing section; if the remaining thickness is below the minimum for 150 psig, the boiler cannot be returned to service at that pressure. If the groove is shallow and within limits, the inspector may document it for monitoring, but should not promise that it can be deferred for six weeks without an engineering evaluation. If repair is needed, a welded repair or tube-sheet replacement must be done by an R-stamp holder using a qualified procedure, with required NDE and an R-1 report. If repair is not practical, the MAWP must be reduced. The inspector should require the evaluation before certificate renewal and should not accept a verbal 'we will watch it' plan.