307A steam and condensate systems practice questions.

Five free practice questions on steam and condensate systems: block D of the Red Seal 307A Steamfitter/Pipefitter exam, about 24 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 · Installs piping for high pressure steam and condensate systems

   You are laying out a pressure-reducing station that drops 125-psig steam to 15 psig at a hospital. In the direction of flow, which order of components is correct (bypass and gauges aside)?

   1. Isolation valve, strainer, PRV, isolation valve, safety relief valve
   2. Safety relief valve, strainer, PRV, isolation valve
   3. Isolation valve, PRV, strainer, safety relief valve, isolation valve
   4. Isolation valve, strainer, safety relief valve, PRV, isolation valve
   Show the answer

   A. Correct. A drip ahead of the station, then isolation, a strainer to protect the PRV seat, the PRV, downstream isolation, and a safety relief on the low-pressure side sized for full PRV capacity. Add gauges both sides and a globe-valve bypass. The downstream pipe is usually larger because low-pressure steam takes more volume.

   Why not the others

   B. The safety relief protects the low-pressure side, so it goes downstream of the PRV. On the inlet it would see full boiler pressure.

   C. The strainer must be ahead of the PRV to protect its seat. After the PRV it does nothing for the valve.

   D. A relief valve ahead of the PRV protects nothing downstream. The low-pressure equipment needs the relief after the PRV.

2. Procedural · Installs piping for low pressure steam and condensate systems

   A 160-ft (49 m) low-pressure steam main in a school is to be pitched down in the direction of flow at the specified grade of 1 in per 40 ft. How much lower is the far end than the boiler end?

   1. 16 in
   2. 40 in
   3. 4 in
   4. 0.25 in
   Show the answer

   C. Correct. 160 ft ÷ 40 ft = 4 units of grade, and 4 × 1 in = 4 in (about 100 mm) of drop. Pitching the main down with the flow lets condensate travel with the steam to the drip at the end of the main.

   Why not the others

   A. This used 1 in per 10 ft instead of the specified 1 in per 40 ft. Read the grade exactly as the specification gives it.

   B. This treated the grade as 1/4 in per foot, which is a drainage slope, not the steam-main grade in the specification. 1 in per 40 ft over 160 ft is 4 in.

   D. This divided 40 by 160, which inverts the grade. Grade is drop over run: 1 in for every 40 ft, so a longer run gives a bigger drop.

3. Procedural · Tests high pressure steam and condensate systems

   The boundary for a 225-psig hydrostatic test in a food plant includes a PRV station (125 to 15 psig) and its downstream relief valve set at 25 psig. How are these handled for the test?

   1. Remove the PRV and relief valve and fit spools or blinds
   2. Close the PRV isolation valves and test through the bypass
   3. Gag the relief valve and leave the PRV in the line
   4. Leave them in, since the PRV will hold the downstream side at 15 psig
   Show the answer

   A. Correct. Components not rated for the test or that would be damaged by it (PRVs, relief and safety valves, instruments, some expansion joints) are removed and replaced with temporary spools, or blanked off, and logged on the blind or spool list for reinstatement.

   Why not the others

   B. The bypass still exposes the low-pressure side and its relief valve to test pressure, and closed isolation valves may pass. The devices must be taken out of the test.

   C. Gagging a relief valve and exposing both devices to 225 psig risks damage to their seats and diaphragms. They are removed or blanked, not gagged in place.

   D. A PRV is not a test boundary and is not rated to regulate water at test pressure. The relief valve would lift and the low-pressure side could be overpressured.

4. Recall · Installs equipment for low pressure steam and condensate systems

   Which trap type is the usual choice for a hospital air-handler steam coil that is fed through a modulating control valve?

   1. Float and thermostatic trap
   2. Thermodynamic disc trap
   3. Bimetallic thermostatic trap
   4. Thermostatic radiator trap
   Show the answer

   A. Correct. The F&T trap discharges continuously in proportion to the load, works down to very low differential pressure, and its built-in thermostatic element vents air at start-up, which suits a modulating coil. It must be installed level.

   Why not the others

   B. A disc trap needs a good pressure differential to cycle. On a modulating coil the pressure can fall close to zero, and the disc trap then holds condensate back or fails to close properly.

   C. A bimetallic trap only opens once the condensate has cooled well below steam temperature, so it backs condensate up into the coil. That suits tracers, not a modulating heating coil that must not flood.

   D. A radiator trap is a small balanced-pressure element sized for radiators and convectors on LP heating. It lacks the capacity and does not discharge at steam temperature, so the coil would flood.

5. Recall · Installs equipment for high pressure steam and condensate systems

   In a high-pressure boiler plant at a university, why is the deaerator storage tank mounted well above the boiler feed pumps?

   1. To keep the tank above flood level in the basement
   2. To raise feedwater pressure to boiler pressure
   3. To give the feed pumps enough NPSH so the hot water does not flash
   4. So the deaerator can drain by gravity to the condenser
   Show the answer

   C. Correct. Water in the deaerator is at saturation, so any pressure drop at the pump suction would flash it and make the pump cavitate. The static head from mounting the tank high gives the net positive suction head the pumps need.

   Why not the others

   A. Flood protection is not the design reason. The height is set by pump suction needs.

   B. The elevation adds only a few psi. The feed pumps provide the pressure needed to enter the boiler.

   D. Deaerated water goes to the feed pumps and on to the boiler. It does not drain back to a condenser.

02Answer key

03What block D covers

This block covers low and high pressure steam and condensate systems. It includes heating and power boilers, Hartford loops, steam tables, latent heat and superheat, main pitch, drips and runouts, steam traps, condensate pumps and flash tanks, PRV stations and safety valves, deaerators, hydrostatic and pneumatic tests, boiler water treatment and blowdown, and warming up steam mains safely.

The Red Seal Occupational Standard names this block “Installs, tests, maintains, troubleshoots and repairs low and high pressure steam and condensate systems”. It carries 18.5% of the exam, about 24 of the 130 questions, split across two tasks. The share column is each task's weight within the block, as the standard publishes it.

04What the questions turn on

15 psig is the code line

A steam heating boiler built to ASME Section IV may not run above 15 psig. Above that it is a power boiler built to Section I, with B31.1 boiler external piping, registered with the provincial authority under CSA B51.

Keeping mains drained

Take runouts off the top of the main or at 45° up, and fit eccentric reducers flat side down so condensate cannot pond. Put a drip leg and trap at the foot of every riser, where condensate collects before the main turns up.

PRV stations and relief sizing

In flow order, a reducing station runs isolation valve, strainer, PRV, isolation valve, then a safety relief on the low-pressure side. That relief is set at or below the downstream rating and sized for the PRV failing wide open.

Telling flash steam from live steam

A lazy white cloud at a trap outlet can be flash steam from hot condensate. A clear, high-velocity jet, a steady roar with no cycling and an outlet at steam temperature mean the trap is blowing live steam.

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.