Layout, Fabrication & Piping — Steamfitter/Pipefitter (307A) Practice Questions

Free Layout, Fabrication & Piping practice questions

1. 1.The root gap for a butt weld joint on Schedule 40 pipe is typically:

   • A.Zero
   • B.1/16" to 3/32" (1.5-2.5mm)✓
   • C.1/4"
   • D.1/2"

   Why: Standard root gap = 1/16-3/32" allows full root penetration. Too narrow = lack of penetration. Too wide = burn-through. Consistent gap is maintained with spacers or tack welds.

2. 2.An expansion loop in a steam line is designed to:

   • A.Increase pressure
   • B.Absorb thermal expansion of the pipe to prevent excessive stress on anchors and equipment✓
   • C.Reduce flow
   • D.Filter steam

   Why: Steel pipe expands ~1" per 100 feet per 100°F temperature rise. Expansion loops, offsets, and bellows absorb this growth, preventing overstressing pipes, supports, and connected equipment.

3. 3.A raised face (RF) flange gasket sits on:

   • A.The entire flange face
   • B.The raised portion only, providing concentrated sealing pressure✓
   • C.The bolt holes
   • D.The pipe ID

   Why: The raised face concentrates bolt load onto a smaller gasket area, increasing sealing pressure. RF flanges use standard gaskets. RTJ (Ring Type Joint) flanges use metal ring gaskets for higher pressures.

4. 4.Socket weld fittings require what gap between the pipe end and the fitting shoulder?

   • A.Zero — fully bottomed out
   • B.1/16" (1.5mm) gap to allow for thermal expansion and prevent bottoming stress✓
   • C.1/4" gap
   • D.1" gap

   Why: Insert pipe fully into socket weld fitting, then pull back 1/16" before tacking. This gap prevents thermal expansion from cracking the weld. Mark the pipe before insertion as a reference.

5. 5.Thermal expansion of carbon steel pipe is approximately:

   • A.Zero
   • B.0.75" per 100 feet per 100°F rise (6.33 × 10⁻⁶ in/in/°F)✓
   • C.2" per foot
   • D.Unpredictable

   Why: Carbon steel: ~0.75" per 100ft per 100°F. A 200ft steam line going from 70°F to 370°F (300°F rise) expands: 0.75 × 2 × 3 = 4.5". This growth must be accommodated.

6. 6.Non-destructive examination (NDE) of pipe welds includes:

   • A.Visual only
   • B.Radiography (X-ray), ultrasonic, magnetic particle, liquid penetrant, and visual examination✓
   • C.Only hammering
   • D.Only paint inspection

   Why: NDE methods detect weld defects without destroying the weld. Radiography and UT for internal defects; MT for surface/near-surface on ferromagnetic; PT for surface defects on all materials.

7. 7.Purging with inert gas during stainless steel welding prevents:

   • A.Nothing
   • B.Oxidation (sugaring) of the root side, which weakens and corrodes the weld✓
   • C.The pipe from moving
   • D.Cooling too fast

   Why: Stainless steel root passes require argon purge on the back side. Without purging, chromium oxidizes (sugaring), depleting corrosion resistance and creating a brittle, porous root.

8. 8.A pipe shoe allows:

   • A.Nothing special
   • B.The pipe to slide along a support while the shoe protects the pipe insulation from damage✓
   • C.Walking on the pipe
   • D.Electrical connection

   Why: Pipe shoes lift insulated pipe off the support steel, allowing axial sliding while protecting the insulation and pipe from abrasion at the support point.

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