ISO 21013-2:2007

Overview

ISO 21013-2:2007 - Cryogenic vessels: Pressure‑relief accessories for cryogenic service - Part 2 covers the design, manufacture and testing of non‑reclosable pressure‑relief devices for cryogenic service. It is focused on bursting‑disc and buckling‑pin devices (size DN 200 and below) intended to relieve single‑phase vapours or gases at temperatures from ambient down to cryogenic. ISO 21013-2 sets material, testing, marking and cleanliness requirements for safe operation with cryogenic fluids. (Sizing and capacity methods are outside its scope - see ISO 21013‑3.)

Key topics and technical requirements

• Scope limits: applies to non‑reclosable bursting‑disc and buckling‑pin devices ≤ DN 200, single‑phase vapour/gas service.
• Design temperatures: rated minimum = equilibrium temperature at atmospheric pressure of the coldest fluid; rated maximum normally +65 °C unless otherwise specified. Coincident temperatures default to 20 °C (ambient) and 427 °C (fire) unless specified.
• Materials & compatibility: metallic and non‑metallic materials must meet toughness and low‑temperature requirements (see ISO 21028‑1/‑2). Materials must be compatible with process fluids and oxygen‑compatible when relevant (ISO 21010). Hydrogen and acetylene compatibility provisions referenced (ISO 11114; copper content <70% for acetylene mixtures).
• Sublimating fluids: devices must avoid reduction of discharge area from solid deposition (e.g., CO2).
• Testing: type approval follows ISO 4126‑2; production tests include pressure/operational tests, leak testing (e.g., helium mass spectrometer or pneumatic under‑water test) and visual examination for non‑replaceable assemblies.
• Cleanliness: all parts must satisfy ISO 23208 cleanliness requirements for cryogenic service.
• Performance tolerances: burst‑pressure tolerance at rated disc temperature - ±15% up to 3 bar; ±5% for 3 bar and over.
• Marking & traceability: permanent marking requirements include manufacturer, model/type, DN, material, burst pressures and temperatures, direction of flow, ISO reference, batch identity, flow area, year of manufacture, certified discharge coefficient, etc.
• Prevention of substitution: coding or equivalent to prevent incorrect replacement discs; manufacturers must retain coding records and quality systems.

Applications and who uses it

ISO 21013‑2 is used by:

• Manufacturers of bursting discs, buckling pins and holders (design, production and QA).
• Cryogenic vessel designers and fabricators specifying pressure‑relief accessories.
• Safety and process engineers specifying relief devices for storage, transport and process systems handling cryogenic gases.
• Test laboratories, inspection bodies and procurement teams verifying compliance, marking and traceability.
  Practical applications include safe overpressure protection of cryogenic tanks, dewars, transportable vessels and associated piping where non‑reclosable relief is required.

Related standards

• ISO 21013‑1 (reclosable pressure‑relief valves)
• ISO 21013‑3 (sizing and capacity determination)
• ISO 4126‑2 (bursting disc safety devices)
• ISO 21028‑1/‑2 (materials toughness at cryogenic temperatures)
• ISO 23208 (cleanliness for cryogenic service)
• ISO 21010, ISO 11114, ASME B16.34, CGA guidance (compatibility and complementary requirements)