Common Occupational Skills — Steamfitter/Pipefitter (307A) Practice Questions

Free Common Occupational Skills practice questions

1. 1.What is the minimum hydrostatic test pressure for a steam piping system per B51?

   • A.Operating pressure
   • B.1.5 × maximum allowable working pressure (MAWP)✓
   • C.50 PSI
   • D.Equal to design pressure

   Why: CSA B51 requires hydrostatic testing at 1.5× MAWP for steam and pressure piping. The test is held for a minimum duration while inspecting for leaks. Never use pneumatic test without engineering approval.

2. 2.When reading a P&ID, a line with double slashes indicates:

   • A.Drain line
   • B.An insulated pipe✓
   • C.A flex connector
   • D.An electrical line

   Why: Double slashes (or II marks) across a pipe line on a P&ID indicate insulation. Different P&ID standards may vary, but this is the most common convention.

3. 3.When performing hot work near piping containing flammable substances, what is required?

   • A.Nothing special
   • B.A hot work permit, fire watch, atmospheric monitoring, and purging/isolation of the piping✓
   • C.Just a fire extinguisher
   • D.Only supervisor notification

   Why: Hot work permits, continuous fire watch, atmospheric gas testing, and proper purging/isolation of adjacent piping are mandatory. Many incidents occur from inadequate purging.

4. 4.Pipe schedule determines:

   • A.Pipe colour
   • B.Wall thickness for a given nominal pipe size✓
   • C.Pipe length
   • D.Pipe material

   Why: Schedule (40, 80, 160, etc.) defines wall thickness. Higher schedule = thicker wall = higher pressure rating. Schedule 40 is standard, Schedule 80 for higher pressures, XXS for extreme.

5. 5.A pipe's allowable working pressure depends on:

   • A.Only the diameter
   • B.Material, wall thickness (schedule), temperature, and applicable code allowable stresses✓
   • C.Only the length
   • D.Only the schedule number

   Why: Working pressure = (2 × S × t) ÷ D, where S = allowable stress (material/temp dependent), t = wall thickness, D = outside diameter. Temperature derates allowable stress significantly.

6. 6.What is the take-out (make-up) dimension for a 90° butt-weld elbow on NPS 4 Schedule 40?

   • A.Same as pipe OD
   • B.Equal to 1.5 × nominal diameter for long radius (6" for NPS 4)✓
   • C.Random
   • D.Equal to the pipe length

   Why: Long radius (LR) 90° elbow: center-to-face = 1.5 × NPS. For NPS 4: 1.5 × 4 = 6". Short radius (SR): center-to-face = 1 × NPS = 4". LR is standard; SR for tight spaces.

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