Doc. 133/14Cryogenic Vaporisation Systems - Prevention of Brittle Fracture of Equipment and Piping

"Cryogenic (or cold) fluids can be inadvertently admitted to process piping and equipment due to the malfunctioning of cryogenic liquid vaporisation systems, which can result in catastrophic failure due to brittle fracture.

When certain metals, typically carbon steels, become cold they undergo changes in their structure, which makes them less ductile i.e., they become brittle and may fail. Other metals such as stainless steels, aluminium, brass, copper do not exhibit this ductile/brittle transition and remain ductile at low temperatures.

This publication applies to cryogenic liquid supply systems, located either on a customer site or a production site, where cryogenic liquid is vaporised and is then supplied either as the primary or secondary source of gaseous product.

This guideline is limited to the prevention of brittle fracture in piping and associated equipment. The secondary source of supply can be a back-up supply to a production plant when the production plant trips or is shut down, a supplementary supply to meet customer demand where it exceeds the capacity of the production plant (“peak-shaving”), or as a back-up supply at a customer site (e.g. a healthcare facility).

The principles presented in this document apply to any low temperature process fluid supply system where the temperature of the fluid is lower than the minimum temperature rating of the piping and/or associated equipment downstream of the vaporiser.

This publication has been written to identify the hazards associated with cryogenic liquid vaporisation systems and to recommend the safeguards to be taken. It recommends safe practice for the design of new cryogenic vaporiser systems.

For existing systems a risk assessment shall be undertaken to establish if any modifications are required. The publication is part of the programme to develop Globally Harmonized publications amongst Regional Gas Associations."