Overview
ISO 21157:2018 - Ships and marine technology - Ball valves for use in low temperature applications - Specifies design, manufacturing and test requirements for cryogenic ball valves intended for very low temperature service (‑196 °C to 80 °C). The standard targets valves used in marine and shipboard systems where leakage stability, mechanical integrity and safe operation at cryogenic temperatures are critical.
Key topics and requirements
This standard addresses the full lifecycle of cryogenic ball valves with clear, testable requirements:
- Scope and definitions - Nominal diameter (DN), nominal pressure (PN) and other terms used for marine valve sizing and rating.
- Pressure–temperature rating - Requirements for selecting ratings based on material and operating temperature.
- Valve structure and materials - Design and material specifications for the body, extended bonnet, ball, stem, seats and bolting to ensure low‑temperature performance and toughness.
- Sealing and stem sealing - Requirements to maintain leakage stability at cryogenic temperatures.
- Operating devices and actuators - Requirements for actuators and part‑turn attachments compatible with ISO 5211.
- Welding, heat treatment and repair welding - Controls on fabrication, post‑weld heat treatment and repair methods to preserve low‑temperature properties.
- Surface treatment - Corrosion protection and finishing requirements suitable for marine environments.
- Testing and inspection - Comprehensive inspection regime including material tests, dimensional and visual checks, non‑destructive testing (RT, PT, UT), pressure testing (ambient and method procedures), anti‑static and optional fire‑resistance tests.
- Cryogenic tests - Specific test procedures and submission requirements for verifying performance in the specified temperature range.
- Marking and documentation - Requirements for traceability and valve identification.
Applications and who uses it
ISO 21157:2018 is intended for organizations involved in design, procurement, manufacture, certification and operation of marine cryogenic valves:
- Valve manufacturers designing and qualifying ball valves for LNG, liquefied gas and other cryogenic services on ships and offshore units.
- Shipbuilders and marine engineers specifying valves for piping, cargo systems and low‑temperature process lines.
- Classification societies, regulatory bodies and inspection authorities verifying compliance and safety.
- Procurement and QA/QC teams ensuring purchased valves meet marine cryogenic performance and testing expectations.
Related standards
ISO 21157 references and aligns with several standards relevant to valve design and testing, including ISO 5208, ISO 5211, ISO 28921‑1, API 6D, API 6FA, ASME B16.x and relevant ASTM and MSS specifications for materials and flanges.
Keywords: ISO 21157:2018, cryogenic ball valves, low temperature applications, marine ball valves, design and testing requirements, pressure‑temperature rating, non‑destructive inspection, cryogenic testing.
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