Brazing (medical gas copper)

HTM 02-01 (2026) Part A says only copper-to-copper joints should be permitted on site, apart from mechanical joints, made with filler rods that need no flux: CP104 alloy to BS EN ISO 17672. Oxygen-free nitrogen (OFN) should be used as an internal inert gas shield on all medical gas pipelines to stop oxides forming inside the pipe, and purging is still needed afterwards to remove the shield gas and other particles. Alloy penetration should be at least three times the tube wall thickness or 3 mm, whichever is greater. Part B classes cutting and brazing a pipeline as high-hazard work under the permit to work.

The Portuguese ACSS ET 03/2006 (revised 2024) asks for joints brazed with nitrogen passing inside and a solder with at least 40% silver. The dental gas and vacuum chapter of the 2021 edition of NFPA 99 (Category 2 systems), as reproduced in a 2021 NFPA committee report, required a brazing alloy melting above 538 °C (1000 °F) to keep the piping intact in a fire, BCuP filler metal without flux for copper-to-copper joints, and a continuous purge with oil-free, dry nitrogen NF. NFPA lists 2027 as the current edition of NFPA 99.