Piping Pipe Welding and Fabrication

Question 1

What welding process is most commonly used for root pass welding on carbon steel process piping?

Accepted Answer

Shielded Metal Arc Welding (SMAW) or Gas Tungsten Arc Welding (GTAW)

Answer

Gas Metal Arc Welding (GMAW)

Answer

Submerged Arc Welding (SAW)

Answer

Flux-Cored Arc Welding (FCAW)

Question 2

What is the purpose of preheat in pipe welding?

Accepted Answer

To reduce the risk of hydrogen-induced cracking and improve weld quality

Answer

To increase welding speed

Answer

To remove mill scale before welding

Answer

To soften the base metal for easier cutting

Question 3

What is a Welding Procedure Specification (WPS)?

Accepted Answer

A document prescribing the variables to be used when making a production weld

Answer

A document listing the welder's qualifications

Answer

A record of production weld repairs

Answer

A material certification for filler metal

Question 4

What does PWHT stand for in pipe fabrication, and why is it performed?

Accepted Answer

Post-Weld Heat Treatment — done to relieve residual stresses and improve material properties

Answer

Pre-Weld Heat Treatment — done before welding to anneal the base metal

Answer

Partial Weld Heat Treatment — used on partial penetration welds only

Answer

Pipe Wall Heat Treatment — to normalize pipe wall thickness

Question 5

What type of joint preparation is most commonly used for butt welds on pipe with wall thickness greater than 3/16 inch (4.8 mm)?

Accepted Answer

Single-V groove bevel

Answer

Square groove

Answer

Fillet weld

Answer

J-groove

Question 6

What is 'interpass temperature control' in pipe welding?

Accepted Answer

Limiting the maximum temperature of the weld between passes to prevent metallurgical damage

Answer

Controlling the temperature of the welding rod before use

Answer

Monitoring ambient temperature during welding

Answer

Setting the preheat temperature for each pass