_________ acid is most often used as a catalyst in polymerization units.

High temperature hydrogen attack results from exposure to hydrogen at elevated temperatures and pressures. The hydrogen reacts with __________ in steel to produce _________, which cannot diffuse through the steel. The loss of carbides causes an overall loss in strength.

The removal of a material's protective scale by impacting materials is called:

Which material does not have an endurance limit?

__________ caustic concentrations and ________ temperatures increase the likelihood and severity of cracking with caustic embrittlement.