Used Boiler With No Data Report and an Uncertified Relief Valve
A used 250 hp firetube boiler rated 150 psig is purchased at auction and moved to a Michigan plant. The nameplate is painted over; the U-1 data report and ASME stamp are not available. The safety valve is stamped 175 psig and has no capacity certification. The boiler shell has a 4 in long, 1/8 in deep groove near the bottom blowdown connection, and a local welder proposes to weld a patch without preheat or post-weld heat treatment. The plant wants to set the boiler at 125 psig to avoid the 150 psig limit, install it, and fire it before the state inspector arrives. The boiler is in a room with a 10 ft ceiling and a 36 in front clearance.
1. What must be established before this used boiler can be installed and fired? Address nameplate, data report, safety valve, and inspector.
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It cannot be fired as planned. A boiler is a pressure vessel with a required data report, nameplate, and stamp; paint over the nameplate does not remove the requirement. The purchaser must obtain the manufacturer's data report and nameplate details or have the boiler evaluated by a qualified engineer and the jurisdiction. The safety valve is wrong: 175 psig set on a 150 psig boiler exceeds MAWP, and the capacity is uncertified. A certified valve set at or below 150 psig with adequate capacity is required. The installation needs a permit, plans, and inspection before firing. The state inspector should be contacted before installation, not after. If the boiler is secondhand, the jurisdiction may require internal and external inspection, a hydrotest, and documentation of any repairs. Setting it at 125 psig does not cure missing paperwork or an unacceptable shell defect.
2. The local welder wants to patch the groove near the blowdown connection. What is the correct repair path?
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The groove is near a high-stress connection and may be wastage, a crack, or a mechanical gouge. The first step is inspection-visual, PT or MT, and thickness gauging-to determine depth and cause. If repair is needed, it is a code repair, not a field patch. The repair organization should hold the appropriate certification (an R-stamp under NBIC for repairs and alterations), use a qualified welding procedure and welder, and have the repair inspected by an authorized inspector. The jurisdiction may require notification and approval. Preheat and post-weld heat treatment depend on material, thickness, and procedure; the local welder's plan omits these. A patch over a groove can trap corrosion or crack growth. Depending on evaluation, the correct fix may be grinding out within allowable limits, replacing the connection, or retiring the boiler. Do not fire it until the repair is documented.
3. What installation clearances and relief piping checks should be made before approval?
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Check the manufacturer's drawing and the adopted code for clearances to combustible construction, access to the front and rear, and room ventilation. A 10 ft ceiling and 36 in front clearance may be adequate or not depending on boiler size, burner, and local rules; do not assume. The relief valve discharge must be piped independently, short and direct, with no valves, and arranged to avoid injury and back pressure. The discharge should not be reduced or tied into a common header unless engineered. Verify combustion air openings, flue draft, and that the safety valve is accessible for testing. The boiler room should have proper exit and ignition-source controls. The inspector will also want the foundation, anchorage, and electrical interlocks checked. Approval comes after the data report, repair records, relief valve certification, and a successful hydrotest and inspection.