This publication provides recommendations and minimum requirements for the design and safeguards of utility and instrument gas systems and their interconnections, both permanent and temporary. It includes startup systems as well as maintenance and continuous purge connections. It identifies the potential hazards resulting from the connections between purge gases, instrument gases, and the process. These requirements may also be considered for existing facilities.

This publication does not cover process or product cross-contamination issues, but some of the principles covered in this publication could apply.

This publication does not cover breathing air systems.

This publication was developed around and applies to HYCO plants, which are facilities that produce hydrogen and/or carbon monoxide. These plants are typically operated with feed stocks such as natural gas, refinery off gas, naphtha, and other light hydrocarbons. The principles and concepts identified in this publication are applicable to other segments of the gases industry (for example, specialty gas plants and air separation units), although some of the scenarios described might not apply and some design details can require modification. Other technologies could require either more or less stringent minimum requirements depending on the specific application, whether contamination is a safety concern or a quality or reliability concern, and the severity of any consequences.

CGA P-8.9 is intended for the guidance of those persons directly associated with the design, installation, operation, and maintenance of bulk cryogenic liquid storage systems. It does not claim to cover the subject completely but gives advice and should be used with sound engineering judgment. The intent of this guide is to ensure that a minimum, uniform level of safety is provided throughout the industrial gas industry for the protection of the public and industry employees.

This publication presents recommendations to reduce the possibility of large releases of stored cryogenic fluids from a storage system through installation of protective equipment and instrumentation, equipment inspection and testing, and storage system design criteria. It is the intent of this publication to emphasize prevention of releases. However this publication provides basic information about mitigation of releases even if they are remote.

A bulk liquid storage installation is defined, for the purpose of this publication, as the total fixed assembly of liquid storage tank(s) integrated with other equipment, such as pumps, filling equipment, pressure buildup vaporizers, controls and other related ancillary equipment that are connected to it.

This publication specifically covers storage installations on production sites where the storage tank is flat bottomed constructed and is connected to the production process plant and the individual tank capacity exceeds 125000 liters. For storage installations made with vacuum insulated tanks or cluster tanks or where the tanks have an individual capacity less than 125000 liters it is an individual company or storage system owner’s decision to use the present publication as a guide for the general requirements of the installation.