I. Why butterfly valve standards are important?
The standard specifies the design of butterfly valves and the tests that each valve must pass. Without these standards, the security of the system cannot be guaranteed. Valves cannot be aligned, components cannot match, and the entire piping system is exposed to unnecessary risk.
The butterfly valve specification standard you follow determines the flange connection method, pressure rating and material grade. This means engineers need to match each butterfly valve standard to the pressure, flow and media of the system to ensure everything is functioning properly.
This article focuses on several common ISO butterfly valve standards and explains them in detail:
II. Butterfly Valve Core Product Standards
| Standard NO. | Standard Name | Scope of application | Key Technical Parameters and Details |
| ISO 10631 | Industrial valves – Metallic butterfly valves | Metal butterfly valves with nominal dimensions DN40~DN2000 and pressure levels PN10~PN400 | Structural form (center symmetry/eccentricity), sealing grade (ISO 5208 Class A~F), material requirements (valve body, butterfly plate, sealing ring) |
| ISO 21159 | Metallic butterfly valves for low-temperature service | Low temperature working conditions with working temperature ≤-46℃ (such as LNG, liquefied gas) | Low-temperature material toughness requirements (-196°C impact test), sealing structure anti-cold flow design, low-temperature torque test method |
| ISO 16136 | Thermoplastic butterfly valves | PVC, PP, PVDF and other thermoplastic butterfly valves with nominal sizes DN50~DN1200 | Plastic valve body pressure rating (PN6~PN16), heat deformation temperature requirements, sealing pair chemical corrosion resistance (ISO 175 test) |
| ISO 22306 | Fibre-reinforced plastic butterfly valves | Glass fiber reinforced plastic (GRP) butterfly valve with nominal size DN100~DN3000 | Fiber laminate structural strength (ISO 527 tensile test), UV aging resistance(ISO 4892-3), sealing pair wear resistance |
III. Butterfly valve supporting technical standards
| Standard NO. | Standard Name | Scope of application | Key Technical Parameters and Details |
| ISO 5752 | Metallic valves – Face-to-face and centre-to-face dimensions | General specification for structural length of all metal valves (including butterfly valves) | Short series (Series A/B), long series (Series C/D) dimension table, flange connection end face parallelism tolerance (≤0.3mm) |
| ISO 5211 | Valves – Mounting of actuators | Connection interface between the valve and the pneumatic/electric actuator | Square drive shaft size (such as 25×25mm), keyway width tolerance (±0.1mm), torque transmission efficiency (≥95%) |
| ISO 5208 | Metal valves – Pressure testing | Test methods for shell strength and tightness of metal valves (including butterfly valves) | Shell test pressure (1.5×PN), seal test pressure (1.1×PN), leakage rate grade (ISO 5208 Class A~F) |
| ISO 10497 | Testing of valves – Fire type-testing requirements | Fire safety performance of valves used in petrochemical industry | Flame exposure time (30 min), internal pressure (2.1 MPa), leakage rate limit (≤ 0.5 L/min) |
| ISO 15848-1 | Measurement of fugitive emissions | Valve methane/VOCs leakage rating assessment | Leak rate classification (A~F), detection method (helium mass spectrometer/bubble method), seal life requirements (≥100,000 cycles) |
IV. Basic General Standards
| Standard NO. | Standard Name | Scope of application | Key Technical Parameters and Details |
| ISO 16046 | Valves – Terminology | Basic Terminology Definitions for All Valve Types | Special terms for butterfly valves (such as “double eccentric”, “triple eccentric”, “soft seal”, “hard seal”) |
| ISO 15848-2 | Product acceptance test | Leak detection process during valve production | Sampling plan (AQL 1.5), detection pressure (1.1×PN), qualification criteria (≤0.1% rated flow) |
V. Benchmarking Analysis of Mainstream Standard Systems
| ISO Standard |
API 609 (American Standard) |
GB/T 12238 (National Standard) | EN 593 (European Standard) | Benchmarking Instructions |
| ISO 10631 | API 609 Category A/B | GB/T 12238-2008 | EN 593-2013 | All three cover metal butterfly valves, but API 609 emphasizes the “double eccentric” design, and EN 593 adds “triple eccentric” structural requirements |
| ISO 5752 | API 609 Appendix B | GB/T 12221-2005 | EN 558-1/2 | ISO 5752 is fully compatible with EN 558, and GB/T 12221 adds China-specific nominal dimensions (such as DN2500) |
| ISO 5208 | API 598 | GB/T 13927-2008 | EN 12266-1 | The test methods of the three are the same, but API 598 allows a higher leakage rate (Class VI), and ISO/EN has stricter requirements (Class A) |
| ISO 10497 | API 607/6FA | GB/T 23935-2009 | ISO 10497 (Equally adopted) | The fire test conditions are exactly the same, but API 6FA adds additional requirements for “low temperature impact” |
VI. Summary & Recommendations
1. Standard coverage completeness: The ISO standard system has fully covered the entire life cycle of butterfly valves from design, manufacturing to testing, and is especially good at emerging fields (such as low temperature, plastic valves).
2. Differences in technical parameters:
- Sealing level: ISO 5208 and EN 12266 are more stringent (Class A leakage rate ≤0.05% rated flow), API 598 allows Class VI (≤0.3%).
- Fire protection requirements: ISO 10497 and API 6FA test conditions are consistent, but ISO does not mandate low-temperature impact testing.
3. Enterprise Bid Selection Suggestions:
- Exporting to Europe: Priority is given to ISO/EN double standard certification (such as ISO 10631+EN 593).
- Exporting to the United States: Special certifications for API 609 (structure) and API 598 (testing) are required.
- Domestic Projects: GB/T 12238 can cover regular needs, but high-end projects are recommended to comply with ISO 15848 (low leakage) simultaneously.
Butterfly valves, gate valves, check valves, although the valves are different, the safety is the same. Tianjin Tanggu Water-Seal Valve Co., Ltd. adheres to the ISO standard system, builds quality with rigor, and wins trust with professionalism. Based on standards and aiming for the long term – TWS makes the world more fluid.
Post time: Jul-22-2026
