ISO 21159:2018 PDF

Overview

ISO 21159:2018 - Ships and marine technology - Butterfly valves for use in low temperature applications - Design and testing requirements - defines design, manufacture and test methods for cryogenic butterfly valves intended to provide stable, low-leakage performance between −196 °C and 80 °C. It applies to specified nominal sizes (DN 80–600 / NPS 3–24) and is aimed at valves used in marine and shipboard low‑temperature services.

Key topics and technical requirements

ISO 21159:2018 sets out requirements across the valve lifecycle with emphasis on materials, structure and verification. Major topics include:

• Scope and ratings
  • Pressure–temperature rating requirements for cryogenic service.
• Structure, materials and manufacturing
  • Body, extended bonnet, disc, stem, seat and connection design rules.
  • Material selection guidance tailored to low‑temperature toughness and compatibility.
  • Welding, heat treatment and repair welding provisions.
• Sealing and stem design
  • Stem sealing arrangements and seat design to achieve excellent leakage stability at cryogenic temperatures.
• Testing and inspection
  • Material tests and non‑destructive examinations (RT, PT, UT).
  • Dimensional and visual inspections; heat treatment verification.
  • Pressure testing at ambient temperature and specific cryogenic tests to confirm leakage performance.
  • Optional fire‑resistance and anti‑static testing where applicable.
• Documentation and marking
  • Test report submission, marking and traceability requirements.
• Nominal sizes
  • DN: 80, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600 (NPS: 3–24).

Applications and users

ISO 21159 is practical for stakeholders involved with maritime cryogenic systems, including:

• Shipbuilders and shipyards specifying valves for LNG, LPG or other cryogenic cargo and fuel systems
• Valve manufacturers designing and certifying butterfly valves for low‑temperature service
• Marine equipment procurement and technical buyers verifying supplier compliance
• Classification societies, notified bodies and testing laboratories performing acceptance and type tests
• Marine engineers and naval architects designing piping systems requiring low‑temperature isolation

Using ISO 21159 helps ensure safety, leakage control and interoperability of butterfly valves in cold‑temperature marine environments.

Related standards (normative references)

ISO 21159 references and aligns with multiple standards commonly used together:

• ISO 5208 (pressure testing of metallic valves)
• ISO 5211 (actuator attachments)
• ISO 28921‑1 (isolating valves for low‑temperature applications)
• ISO 10497 (fire testing of valves)
• API 609, ASME B16 series, ASME V/VIII, ASTM A‑series, MSS SP‑44, MSS SP‑55

These related documents cover dimensions, flanges, testing procedures and material specifications often required in procurement and certification.

Using ISO 21159:2018 ensures valves meet rigorous marine cryogenic design and test expectations for reliable, low‑temperature operation.