CGA G-4.4

The scope of this publication is for metal oxygen pipelines, distribution piping systems, and gaseous oxygen piping on an air separation plant external to the coldbox. The scope is limited to gaseous oxygen with a temperature range between –22 °F and 400 °F (–30 °C and 200 °C), pressures up to 3000 psi (21 MPa), and a dew point of –22 °F (–30 °C) or less depending on local conditions. Although it is possible to safely use oxygen at higher temperatures and/or pressures, such applications are beyond the scope of this publication. In these cases, additional materials testing and/or a risk assessment, as appropriate to the application, shall be undertaken.

This publication does not apply to the following processes:

• oxygen cylinder filling plants;
• medical oxygen piping installations;
• coldbox internal piping;
• oxygen compressor units;
• liquid oxygen vaporizers;
• bulk oxygen facilities (liquid or high pressure gas) at the customer’s site up to the point where gas enters the distribution systems; or
• piping on specialized equipment and machines such as scarfing, jet piercing, etc.

The use of nonmetal piping for oxygen-enriched gases in production plants, transmission systems, or distribution systems is outside the scope of this publication and requires a specific risk assessment and precautions.

The purpose of this publication is to further the understanding of those engaged in the safe design, operation, and maintenance of gaseous oxygen transmission and distribution systems. It is not intended to be a mandatory standard or code.

Some of the practices represent conservative compromises and not all situations are described. The designer is cautioned that this publication is not a complete design handbook and does not do away with the need for competent engineering judgment and interpretation. It is suggested that the user review any special problems or concerns with their oxygen supplier who should be able to provide advice and guidance.