Pipefitter Pipe Fabrication Methods 5

Question 1

What is the purpose of a 'line-up clamp' (internal lineup clamp) used during pipe spool fabrication?

Accepted Answer

To align two pipe ends concentrically and hold them at the correct root gap before welding

Answer

An internal lineup clamp is inserted into both pipe ends to ensure they are concentric and at the correct root gap, preventing misalignment during the root pass.

Question 2

When fabricating a lateral (Y-branch) fitting, the branch pipe intersects the header at an angle typically less than 90 degrees. What is the most critical layout challenge?

Accepted Answer

Developing the accurate compound saddle cut profile on both the header and branch pipe

Answer

The compound saddle cut must accurately match the curvature of the header on the branch pipe end so the joint fits tightly with minimal gap before welding.

Question 3

In fabrication, what is 'back-purging' and when is it required?

Accepted Answer

Filling the inside of a pipe with inert gas to protect the weld root from oxidation, required for stainless steel and reactive alloys

Answer

Back-purging floods the pipe interior with argon or nitrogen to exclude oxygen from the weld root, preventing oxidation (sugaring) in stainless steel and titanium welds.

Question 4

Which ASME standard governs the dimensional requirements for butt-welding fittings used in pipe fabrication?

Accepted Answer

ASME B16.9

Answer

ASME B16.9 covers factory-made wrought buttwelding fittings, specifying dimensions, tolerances, and ratings for elbows, tees, reducers, and caps.

Question 5

When calculating the cut length of pipe between two 90-degree long-radius elbows in the same plane, what must be subtracted from the face-to-face dimension?

Accepted Answer

The takeout (end-to-center) of each elbow — one for each end

Answer

The cut length equals the face-to-face distance minus the takeout of each elbow (one at each end), ensuring the assembled spool matches the drawing dimension.

Certified Pipefitter Practice Test

Certified Pipefitter Practice Test

Pipefitter Pipe Fabrication Methods 5