Vacuum-insulated tanks are widely used to store cryogenic and refrigerated liquids. These tanks use a vacuum between the inner, process vessel, and the outer tank jacket to reduce heat leak into the stored product. This vacuum can be lost, either through normal tank aging or by a leak. The cause of any vacuum loss shall be investigated and the remedial actions taken.

This publication addresses vacuum-insulated tanks containing cryogenic and refrigerated liquids. This publication is particularly important for those systems with a large stored volume and/or systems that may be unattended.

The scope of this publication covers equipment including:

• bulk storage;
• dewars; and
• transportation equipment.

Although this publication addresses vacuum-insulated tanks, some of the principles may also be used for vacuum-insulated equipment such as piping, pumps, etc.