In a WPS, omitting which item requires qualification of a new procedure if the item is listed?

In a WPS, omitting which item requires qualification of a new procedure if the item is listed?

• A. Backing strip
• B. Joint details
• C. Preheat and interpass temp control
• D. Shielding gas

Answer: (A)

A WPS fixes the variables that determine weld quality, so any item listed in it is a controlled condition. If you omit a listed item, you’re deviating from the approved procedure and typically must qualify a new procedure to show that welds made without that item still meet the code’s requirements. A backing strip directly influences the root region of the weld—shaping the root bead, penetration, and cooling at the joint. If the WPS requires a backing strip and you omit it, the root conditions change in a fundamental way, so the original procedure no longer applies. That change in the critical root area is why a new procedure qualification is needed. The other items—joint details, preheat/interpass temperature control, and shielding gas—affect different aspects of the weld, but the backing strip omission most directly alters the root conditions, prompting qualification of a new procedure.

A WPS fixes the variables that determine weld quality, so any item listed in it is a controlled condition. If you omit a listed item, you’re deviating from the approved procedure and typically must qualify a new procedure to show that welds made without that item still meet the code’s requirements. A backing strip directly influences the root region of the weld—shaping the root bead, penetration, and cooling at the joint. If the WPS requires a backing strip and you omit it, the root conditions change in a fundamental way, so the original procedure no longer applies. That change in the critical root area is why a new procedure qualification is needed. The other items—joint details, preheat/interpass temperature control, and shielding gas—affect different aspects of the weld, but the backing strip omission most directly alters the root conditions, prompting qualification of a new procedure.