What is the term for an unintended release of gas from fittings or connections?

The term for an unintended release of gas from fittings or connections is accurately described as a gas leak. In the context of gas systems, a gas leak typically occurs when there is a failure at joints, seams, or other connection points, allowing gas to escape into the surrounding environment. This can pose significant safety hazards, including the risk of fire, explosion, or exposure to harmful gases.

Understanding the terminology related to gas safety is crucial for proper handling and maintenance of gas systems, which is a fundamental aspect of gas practice. The other options, while they have specific meanings in different contexts, do not correctly define the phenomenon of unintended gas release. For instance, gas emission typically refers to the release of gas as part of a process, overflow suggests excess liquid rather than gas, and venting usually implies a controlled release of gas to alleviate pressure rather than an unintended escape. Thus, the correct term in the context of the question is indeed a gas leak.