307A pipe fabrication and valves practice questions.

Five free practice questions on pipe fabrication and valves: block B of the Red Seal 307A Steamfitter/Pipefitter exam, about 29 of its 130 questions. They are in the exam's format: four options, one correct answer. Answer each one before opening the explanation. No account, no email.

01The questions

1. Procedural · Lays out and installs carbon steel piping, fittings and related components

   A 12-inch Class 150 raised-face flange with a spiral-wound gasket is being bolted up in a refinery. How are the bolts tightened?

   1. Clockwise around the flange, each bolt to full torque in turn
   2. Top and bottom bolts to full torque first, the rest by hand
   3. Criss-cross to full torque on the first pass, with no recheck
   4. Criss-cross in stages (about 30, 60, 100 %), then a circular pass
   Show the answer

   D. Correct. Lubricated studs are snugged, then torqued in a star (criss-cross) pattern in stages of roughly 30 %, 60 % and 100 % of the torque-sheet value, followed by a circular pass at 100 % until the nuts stop turning. This compresses the gasket evenly; record it on the torque sheet.

   Why not the others

   A. Taking one bolt at a time to full torque cocks the flange, crushes the gasket on one side and leaves the other side loose.

   B. Full torque on two bolts pulls the flange unevenly and can pinch the gasket. All bolts are brought up together in the pattern.

   C. Going to full torque in one pass loads the gasket unevenly, and bolts relax as their neighbours are tightened. Staged passes and a final circular pass even the load.

2. Procedural · Fabricates piping system components

   A GTAW root is about to be run on a back-purged 316 stainless spool. How is it confirmed that the purge is complete?

   1. The flowmeter is set to its maximum flow
   2. An oxygen analyzer at the vent reads below the WPS limit
   3. A lit match held at the vent goes out
   4. The argon has flowed for the time on the cylinder label
   Show the answer

   B. Correct. An oxygen analyzer sampling at the purge vent shows the residual oxygen is below the limit in the WPS or spec. Only then is the root run, and the purge keeps flowing until the root and hot pass are done.

   Why not the others

   A. High purge flow causes turbulence that draws air in and can push the root concave. Flow is set per the WPS, and the result is confirmed with an oxygen analyzer.

   C. An open flame at a purge vent is unsafe and far too crude; a match goes out at oxygen levels still high enough to oxidize the root. Measure with an oxygen analyzer.

   D. Purge time depends on volume, flow rate, dam placement and leaks, so a fixed time proves nothing. The verification tool named for this is the oxygen analyzer.

3. Procedural · Installs valves

   A PRV in a hospital reduces 125-psig (862 kPa) steam to 15 psig (103 kPa) for equipment rated 30 psig (207 kPa). What must be installed downstream?

   1. A second PRV in series in place of a relief valve
   2. A safety valve set ≤ 30 psig and sized for full PRV flow
   3. A safety valve set at 125 psig to match the inlet
   4. A check valve so steam cannot flow back to the PRV
   Show the answer

   B. Correct. If the PRV fails wide open, the downstream side sees the full 125 psig. A safety (safety relief) valve set at or below the equipment's 30-psig rating and able to pass the PRV's full wide-open capacity protects it. A strainer upstream, isolation, gauges and a bypass complete the station.

   Why not the others

   A. Two-stage reduction is sometimes used, but a pressure-reducing valve is not an overpressure device and can fail open too. A relieving device is still required downstream.

   C. A safety valve set at 125 psig would let 30-psig equipment see four times its rating. It must be set at or below 30 psig.

   D. Backflow into the PRV is not the hazard; overpressure from a failed-open PRV is. A downstream safety valve is required.

4. Procedural · Installs liquid-filled tracing systems

   A new hot-glycol tracing circuit is being filled. How is air removed?

   1. Fill from the high point with every vent closed
   2. Run the pump dry to push the air out
   3. Fill from the low point, venting at high points
   4. Pressurize the loop with air to drive out pockets
   Show the answer

   C. Correct. Filling from the low point pushes air ahead of the liquid to the high points, where the high-point vents are opened until solid liquid (no air) flows, then closed. Air left in the loop blocks circulation. Run the pump and vent again.

   Why not the others

   A. Filling from the top with vents closed traps air at every high point, so circuits air-bind.

   B. Running a pump dry damages the seal and bearings and cannot move air out of the loop.

   D. Adding air makes the problem worse. Air is removed by venting at high points while filling from the low point.

5. Recall · Lays out and installs plastic piping, fittings and related components

   Which joining method is used on PEX tubing?

   1. Butt fusion with a heater plate
   2. Solvent cement with primer
   3. Crimp, clamp or expansion fittings
   4. Tapered threads cut into the tube
   Show the answer

   C. Correct. PEX is joined mechanically: crimp or clamp rings over insert fittings, or expansion rings or sleeves on expanded tubing. Being cross-linked, it cannot be solvent-cemented or butt-fused. Store it out of direct sunlight, which degrades it.

   Why not the others

   A. Cross-linking means PEX will not melt and flow like HDPE or PP, so it is not butt-fused. It uses mechanical fittings.

   B. PEX does not dissolve in solvent cement; solvent welding is for PVC, CPVC and ABS.

   D. PEX tubing cannot be threaded. It connects to threaded fittings through transition adapters that crimp or expand onto the tube.

02Answer key

03What block B covers

This block covers turning drawings into installed pipe. It includes offset and take-off calculations, fit-up, bevels and weld prep, hangers, guides, anchors and spring cans, thermal expansion, copper, PVC, CPVC, HDPE and PEX joining, threading, grooving and flange bolting, stainless steel and FRP, gate, globe, check, butterfly and pressure-reducing valves, valve repacking, and steam and glycol heat tracing.

The Red Seal Occupational Standard names this block “Performs layout, fabrication and piping installation”. It carries 22.3% of the exam, about 29 of the 130 questions, split across four tasks. The share column is each task's weight within the block, as the standard publishes it.

04What the questions turn on

Offsets and cut lengths

For a 45° offset, the travel is the offset times 1.414. The cut length is the centre-to-centre travel less both fitting take-offs. On threaded pipe, the thread engagement at each end is then added back.

Anchors, guides and spring cans

Anchors fix the ends so growth goes into the loop or joint, and guides keep that movement axial. Spring can travel stops carry the hydro test water and must come out before start-up, or the load goes into a nozzle.

Which valve goes where

Gate valves are for full open or full closed, since throttling wire-draws the seat. Globe valves go in with flow entering under the seat. A swing check works horizontal or in vertical lines with upward flow, never with flow going down.

Steam tracing runs downhill

Feed a steam tracer at the high end and run it down to its trap at the low end, so condensate drains by gravity with no pockets. Give each tracer its own trap, since grouped tracers short-circuit and leave some circuits cold.

05The other blocks

The 307A exam has seven blocks. Each has its own page of free questions:

The 307A Steamfitter/Pipefitter practice exam page describes the full question bank. How these questions are written and checked: how our questions are made. Found a mistake? Tell us and we will fix it.