456A SMAW (Shielded Metal Arc Welding) 4

Question 1

Which electrode classification would be most appropriate for welding A516 Grade 70 pressure vessel steel with SMAW?

Accepted Answer

E7016 or E7018

Answer

E7016 or E7018 low-hydrogen electrodes are the standard choice for pressure vessel steels such as A516 Gr 70 because they provide low hydrogen content (preventing HIC), matching tensile strength (~70 ksi/480 MPa), and good toughness. E6010 can be used for root passes.

Question 2

What is 'slag inclusion' in a SMAW weld and what is the primary prevention method?

Accepted Answer

Slag trapped in the weld metal; prevented by thorough inter-pass slag removal and proper technique

Answer

Slag inclusion occurs when solidified flux (slag) becomes trapped within the weld metal during multi-pass welding. Prevention includes thorough chipping and wire brushing between passes, maintaining proper electrode angle to keep the slag behind the weld pool, and using adequate amperage.

Question 3

What does 'burn-through' mean and what is the most likely cause in SMAW on thin material?

Accepted Answer

Complete melting through the base metal; caused by excessive amperage or slow travel speed

Answer

Burn-through is when the arc completely melts through the base metal, creating a hole. On thin material, it is most commonly caused by excessive amperage, too slow a travel speed, or excessive dwell time in one area. Reducing amperage and increasing travel speed are the primary remedies.

Question 4

In SMAW welding of pipe in the 6G position, what does the '6G' designation mean?

Accepted Answer

Pipe axis at 45° to horizontal, pipe fixed (not rotated)

Answer

The 6G position has the pipe axis fixed at 45° to the horizontal. Because the pipe is not rotated, the welder must weld in all positions (flat, vertical, overhead) in a single joint, making it the most demanding qualification test position.

Question 5

What is 'overlap' (cold lap) as a weld discontinuity in SMAW?

Accepted Answer

Weld metal that extends beyond the weld toe onto the base metal without fusing to it

Answer

Overlap (cold lap) occurs when molten weld metal rolls over the toe of the weld and solidifies on the base metal without fusing to it. It is caused by too low an amperage, incorrect electrode angle, or too slow a travel speed. It creates a notch effect and is a rejectable defect.

Red Seal Welder 456A Practice Test

Red Seal Welder 456A Practice Test

456A SMAW (Shielded Metal Arc Welding) 4