ISO 21013-3:2006

Cryogenic vessels — Pressure-relief accessories for cryogenic service — Part 3: Sizing and capacity determination

ISO 21013-3:2006 provides separate calculation methods for determining the required mass flow to be relieved for each of the following specified conditions.

• Vacuum-insulated vessels with insulation system (outer jacket + insulating material) intact under normal vacuum; outer jacket at ambient temperature; inner vessel at temperature of the contents at the relieving pressure.
• Vacuum-insulated vessels with insulation system (outer jacket + insulating material) intact under normal vacuum; outer jacket at ambient temperature; inner vessel at temperature of the contents at the relieving pressure; pressure regulator of the pressure build-up system functioning at full potential.
• Vacuum-insulated vessels with insulation system remaining in place but with loss of vacuum, or non-vacuum-insulated vessels with insulation system intact; outer jacket at ambient temperature; inner vessel at temperature of the contents at the relieving pressure; vacuum or non-vacuum-insulated vessels with insulation system remaining fully or partially in place, but with loss of vacuum in the case of vacuum-insulated vessels, and fire engulfment; inner vessel at temperature of the contents at the relieving pressure.
• Vessels with insulation system totally lost and fire engulfment.

Good engineering practice based on well-established theoretical physical science needs to be adopted to determine the required mass flow where an appropriate calculation method is not provided for an applicable condition.

Edition	2006
Standard Part No	3
Published Date	2006
Published By	International Standardization Organisation
Page Count	8