Скачать или смотреть Purging of gas lines is a core piping repair & installation skill you must understand.

Purging natural gas and flammable gas lines requires a number of considerations to provide the best chances of a safe outcome. Many piping contractors have no idea what it takes and what the rules are. In fact, many have no idea that there are rules. These rules are there because hundreds have been killed and maimed from flammable gas piping project mistakes. These occur on new projects and retrofits. The primary standards and codes for doing these kinds of repairs safely are NFPA 54 and 56. This video introduces you to the concept of purging which is one of the basic building block core understandings you must have to do safe gas piping repairs.
Purging requires that you understand how to safely isolate and depressurize a piping system. It also requires that you understand how to use nitrogen safely. One breath of pure nitrogen can kill you, even though it's 78% of every breath we take. There's lots to learn here and I give you parts of two of my online school modules that relate to the topic as well.