The scope of this document is for metallic transmission and distribution piping systems carrying pure hydrogen and hydrogen mixtures as shown in Figure 1 of Appendix A. It is limited to gaseous products with:

– a temperature range between –40 °C and 175 °C (–40 °F and 347 °F);

– total pressures from 1 MPa (150 psig) up to 21 MPa (3000 psig) or for stainless steels only partial hydrogen pressure higher than 0.2 MPa (29 psig); and

– concentration criteria defined in Appendix G.

Specific guidance is provided in Appendix I concerning ultra high purity (UHP) hydrogen.

This document does not apply to the following processes:

– cylinder filling plants;

– producing plants;

– compressor units;

– bulk 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.

With regard to the preceding [see Appendix K, References 6.1, 8.1, 8.2, 9.1, 9.2, and 12.1]. ¹

The purpose of this publication is to further the understanding of those engaged in the safe design, operation, and maintenance of transmission and distribution systems. It is not intended to be a mandatory standard or code. It contains a summary of the current industrial practices. It is based upon the combined knowledge, experience, and practices of the major producers in Western Europe and North America.

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

Although the technical information provided in this document is not intended to be mandatory, the word "shall" is frequently used. Shall is used to indicate requirements strictly to be followed in order to conform to this document and from which no deviation is permitted. Should is used to indicate that among several possibilities one is recommended as particularly suitable, without mentioning or excluding others, or that a certain course of action is preferred but not necessarily required.

¹ References are shown by bracketed numbers and are listed in Appendix K.

Customers who purchased CGA G-5.6
also purchased

• CGA G-5 : HYDROGEN-SEVENTH EDITION
• CGA G-5.4 : STANDARD FOR HYDROGEN PIPING SYSTEMS AT USER LOCATIONS-Fifth Edition
• CGA G-5.3 : Commodity Specification for Hydrogen-Sixth Edition
• NFPA 55 AMD 2 : Compressed Gases and Cryogenic Fluids Code

See More Documents