# Why must medical gas pipes be cleaned for oxygen?

**Why must pipes and fittings for medical gases be cleaned for oxygen service?**

Medical gas pipes and fittings must be cleaned for oxygen service because oxygen strongly supports combustion and is highly dangerous in contact with oil and grease, and because particles can adversely affect the quality of the delivered gas, as HTM 02-01 (2026) explains.

## The two risks

- Fire: HTM 02-01 (2026) describes oxygen as non-flammable but strongly supporting combustion, and highly dangerous in contact with oils, greases, tar-like substances and many plastics. Oil and grease in the presence of high-pressure oxygen and nitrous oxide are liable to combustion, and rapid pressurisation can lead to ignition by adiabatic compression, particularly when contaminants such as oil or grease are present.
- Gas quality: medical gases are medicines, and the HTM notes that particles can adversely affect the quality of the delivered gas. Even PTFE tape is ruled out on oxygen systems, because fragments can block terminal units and present a fire hazard with high-pressure oxygen.

## What the standards require

- Tube: EN 13348:2016 covers seamless round copper tubes for medical gases or vacuum, from 6 mm to 219 mm outside diameter, for operating pressures up to 2 000 kPa. HTM 02-01 asks for all pipes to be cleaned and degreased for oxygen service, free of particulate matter and toxic residues in accordance with BS EN 13348, and individually capped at both ends.
- Fittings: cleaned and degreased for oxygen service and individually sealed in plastic bags.
- Tools and materials: only oil-free and grease-free tools and dies; pipes cut with wheel cutters, not hacksaws, to keep copper particles out; any swaging lubricant oxygen-compatible; liquid or gel sealing media only if tested to BS EN ISO 15001.
- Site practice: pipeline sections capped as soon as they are completed, to keep debris out.
- Vacuum and AGSS: degreasing is not essential for quality, but HTM 02-01 asks for degreased pipe there too, to avoid confusion.
- Oxygen compatibility: ISO 15001:2010 sets oxygen compatibility requirements for materials, components and devices of anaesthetic and respiratory equipment, such as medical gas pipeline systems, in contact with oxygen above 50 kPa, with guidance on material selection, cleanliness and risk analysis.

In Portugal, ACSS ET 03/2006 (v.2024) requires medical gas networks in copper tube to EN 13348.

## Checked before use

Medical gas pipelines are built from chemically cleaned, capped components with joints made under a shield gas, but site contamination can still occur. On a new system, HTM 02-01 asks for a particulate test with a membrane filter at every terminal unit, and a Quality Controller (MGPS) then verifies the identity and quality of the gases.

### Do vacuum pipes need oxygen cleaning?

HTM 02-01 (2026) says degreasing vacuum pipelines is not essential for quality, but degreased pipe and fittings should be used because vacuum is often installed alongside the medical gas pipelines.

### Can PTFE tape be used on oxygen pipework?

No. HTM 02-01 (2026) says PTFE tape is not an acceptable sealing material on oxygen systems or supply plants.

## Sources

- [HTM 02-01 (2026) Part A, 12.23, 15.71 to 15.73, 15.82, 15.98 to 15.101, 19.222, 19.223, 20.5](https://www.england.nhs.uk/wp-content/uploads/2016/05/health-technical-memorandum-02-01-medical-gas-pipeline-systems-part-a-design-installation-validation-verification-aug-2026.pdf)
- [HTM 02-01 (2026) Part B, 9.102, 9.164, 10.12](https://www.england.nhs.uk/wp-content/uploads/2016/05/health-technical-memorandum-02-01-medical-gas-pipeline-systems-part-b-operational-management-aug-26.pdf)
- [EN 13348:2016 (DIN Media, DIN EN 13348:2016-11)](https://www.dinmedia.de/en/standard/din-en-13348/253294458)
- [ISO 15001:2010, abstract (iso.org)](https://www.iso.org/standard/44250.html)
- [ACSS ET 03/2006 v.2024, section 7.1 (pipework)](https://www.acss.min-saude.pt/wp-content/uploads/2016/10/ET-03_2006_v2024-Gases-medicinais_VF.pdf)

Reviewed: 2026-10-22. Ultra Controlo engineering. https://library.ultracontrolo.com/answers/why-must-medical-gas-pipes-be-oxygen-clean/