CGA P-74 PDF

This standard contains minimum requirements for high pressure tube trailers that store compressed gases and serve as supply systems at customer locations. It details requirements for locating/siting, selecting equipment, installing, starting up, maintaining, and removing tube trailer supply systems.

This standard applies to compressed gas storage systems at customer locations that use tube trailers as the storage vessel. The tube trailers are delivered to and staged at the customer location. This standard does not apply to tube trailers that are used only to deliver compressed gases to permanently-installed gas storage systems such as receivers, where the tube trailers are not staged on site and do not serve as the storage vessel. It does not apply to mobile acetylene trailer systems, which are covered in CGA G-1.6, Standard for Mobile Acetylene Trailer Systems.

Tube trailers provide a means to transport and supply nonliquefied (gaseous) compressed gas products at ambient temperatures. In this publication, the term tube trailer refers to a trailer meeting the requirements of U.S. Department of Transportation (DOT) and Transport Canada (TC) for design, testing, and maintenance.

Standard pressures for tube trailers range from 2000 psi to 3500 psi (13 789 kPa to 24 131 kPa), with some trailers supplying higher pressures up to 10 000 psi (68 947 kPa). A common pressure in use today is 2400 psi (16 547 kPa).

Tube trailers may be used as a direct supply method of various gases to a customer installation. Two primary methods of delivery are typically used with tube trailer supply systems: single trailer installations (with or without permanent ground high pressure back up or storage), and multi-trailer installations. For a single trailer installation, there can be an interruption of service during the change out of the trailers. For a multi-trailer installation, there may be the capacity to have more than one trailer providing gas so during a change out of the trailers there is no need for an interruption of supply.

Tube trailers providing the following gases are within the scope of this publication:

• flammable gases;
• inert gases; and
• oxidizing gases.

Toxic gases (Division 2.3) are not covered in this publication.

The designer shall use the general requirements for all tube trailer supply systems along with the specific requirements for the type of gas stored in a particular tube trailer. For example, tube trailer supply systems for flammable gases such as hydrogen will have more requirements for mitigating ignition hazards than will tube trailer supply systems for inert gases such as helium.

DOT and TC authorized tubes (with or without wheels) shall be designed, maintained, and tested in accordance with the applicable transport regulation(s).

This standard does not apply to medical use or applications. For medical use, refer to CGA M-1, Standard for Medical Gas Supply Systems at Health Care Facilities (an American National Standard).