Refrigeration Plant Operator B Practice Test 2025 – All-in-One Guide to Exam Success

A gas pocket or weld cavity that forms due to gas or moisture being trapped in a weld is known as a blow hole. In welding, blow holes occur when air or moisture gets trapped during the welding process, resulting in a void or cavity in the weld metal once it solidifies. This imperfection can weaken the integrity of the weld and negatively affect the overall strength of the welded joint.

In contrast, a crack refers to a fracture in the weld or base material, which can arise from stress, thermal expansion, or other factors. A crater is a specific type of defect that appears at the end of a weld bead, often caused by improper welding technique or settings, but it does not specifically refer to trapped gas. A root crack specifically refers to a crack that originates at the root of a weld joint, which is a different type of defect altogether. Thus, blow hole is the term that accurately captures the nature of the cavity formed from trapped gases in a weld.