SPED Pipe Fabrication & Welding Standards 3

Question 1

What is the significance of the 'essential variable' concept in ASME Section IX welding qualifications?

Accepted Answer

It identifies variables whose change requires requalification of the WPS

Answer

Essential variables are those welding parameters where a change beyond specified limits is believed to affect the mechanical properties of the weld, requiring a new PQR and revised WPS.

Question 2

According to ASME B31.3, what type of joint must be used for all fluid services in Category M (highly toxic) service?

Accepted Answer

Butt-welded joints for all sizes

Answer

ASME B31.3 Chapter VIII for Category M service requires butt-welded joints throughout to minimize leakage risk for highly toxic fluids.

Question 3

During hydrostatic pressure testing of a piping system per ASME B31.3, the test pressure must be at least:

Accepted Answer

1.5 times the design pressure adjusted for temperature

Answer

ASME B31.3 paragraph 345.4.2 requires hydrostatic test pressure of at least 1.5 times the design pressure, adjusted by the ratio of allowable stress at test temperature to allowable stress at design temperature.

Question 4

What is the maximum allowable mismatch (high-low) between pipe wall interiors at a butt weld per ASME B31.3 for normal fluid service?

Accepted Answer

1/8 inch (3.2 mm) or 25% of wall thickness, whichever is less

Answer

ASME B31.3 paragraph 328.4.3 limits weld joint internal misalignment to 1/8 inch or 25% of the thinner component wall thickness, whichever is less.

Question 5

Which welding process is classified as a 'low hydrogen' process, making it preferred for welding higher-strength and thicker carbon steel pipe?

Accepted Answer

SMAW with EXX18 low-hydrogen electrodes

Answer

EXX18 electrodes have a low-hydrogen flux coating that limits diffusible hydrogen in the weld deposit, reducing the risk of hydrogen-induced cracking in susceptible steels.

(SPED) Society of Piping Engineers and Designers Certification Practice Test

(SPED) Society of Piping Engineers and Designers Certification Practice Test

SPED Pipe Fabrication & Welding Standards 3