Question

the thickness of the root face on a pipe joint is used to?
control the penetration
limit the heat on the joint
limit cracking
limit porosity

Explanation:

The root face thickness in pipe joints is a key factor in welding. It acts as a barrier that controls how deeply the weld penetrates the joint. By having a specific root face thickness, welders can ensure that the penetration is neither too shallow (which could lead to weak joints) nor too deep (which might cause burn - through or other defects).

Answer:

control the penetration