Pipefitter Welding and Joining Techniques 5

Question 1

When qualifying a welding procedure specification (WPS) under ASME Section IX, changing the base metal P-Number typically requires:

Accepted Answer

Requalification of the procedure with a new PQR

Answer

Under ASME Section IX, a change in base metal P-Number is an essential variable that requires requalification of the welding procedure through a new Procedure Qualification Record (PQR).

Question 2

In GTAW (TIG) pipe welding, the high-frequency arc start is preferred over scratch start primarily because:

Accepted Answer

It prevents tungsten contamination of the weld pool

Answer

High-frequency arc starting allows the arc to initiate without touching the tungsten to the base metal, preventing tungsten inclusions in the weld and preserving electrode geometry.

Question 3

What is the correct root opening (gap) typically used when fitting up Schedule 40 carbon steel pipe for SMAW butt welding without a backing ring?

Accepted Answer

1/16 to 3/32 inch

Answer

A root opening of 1/16 to 3/32 inch allows full penetration of the root pass in open-root SMAW pipe welding without excessive burn-through.

Question 4

During pipe welding inspection, a 'hi-lo' gauge is used to measure:

Accepted Answer

The mismatch (internal misalignment) between pipe ends

Answer

A hi-lo gauge measures the internal offset between two pipe ends being joined; excessive hi-lo creates stress concentrations and is limited by welding codes.

Question 5

Which NDE method is most effective for detecting lack-of-fusion defects in a pipe weld that is inaccessible from the inside?

Accepted Answer

Phased array ultrasonic testing (PAUT)

Answer

Phased array ultrasonic testing (PAUT) can detect internal volumetric defects including lack of fusion from the pipe's outer surface without requiring internal access.

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Pipefitter Welding and Joining Techniques 5