Ordering an actuated butterfly valve is not only a valve-selection exercise. The valve, mounting interface, bracket or mounting kit, coupling, gearbox, actuator, controls, and required documentation must work as one assembly.
Two standards published in February 2026 make this an appropriate time to update butterfly valve RFQ templates: ISO 5211:2026, Industrial valves – Part-turn actuator attachments, and ISO 22109:2026, Industrial valves – Gearboxes for valves.
Quick Buyer Verdict
Do not approve an actuated butterfly valve quotation that only states an actuator model and an ISO mounting-flange code.
| RFQ field | Minimum information | Why it matters |
|---|---|---|
| Valve duty | On/off or modulating; normal and emergency operation | Duty affects actuator and gearbox selection |
| Design conditions | Size, class or PN, fluid, pressure, differential pressure and temperature | Torque and material suitability depend on the real service |
| Valve torque | Seating, unseating, running and maximum torque; basis and safety factor | A flange code alone does not size an actuator |
| Interface | ISO 5211 flange, stem or drive dimensions, orientation and drawing | Confirms mechanical compatibility |
| Gearbox and controls | Duty, output, ratio, fail action, cycle time and accessories | Defines complete assembly behavior |
| Documents | GA, interface drawing, torque sheet, datasheets, IOM and test records | Supports approval before shipment |
What Changed in 2026?
ISO lists ISO 5211:2026 as Edition 4, published in February 2026. Its public scope covers requirements for attaching part-turn actuators, with or without gearboxes, to industrial valves. It identifies flange dimensions, driving-component dimensions, and reference torque values for interfaces and couplings.
ISO lists ISO 22109:2026 as Edition 2, also published in February 2026. It covers basic requirements for gearboxes used for manual and automated on/off and modulating valve duties, including manual override gearboxes.
API’s public standards plan shows a 2026 development signal for the next edition of API 609. A standards plan is not the same as a contract-ready publication, so the RFQ should require the bidder to identify the exact API 609 edition used.
ISO 5211 Does Not Replace Torque Data
ISO 5211 helps define the part-turn actuator attachment. It does not provide the complete operating torque for a specific valve in a specific service.
For a triple eccentric butterfly valve, request break-to-open, running, end-to-close and maximum torque in both directions, together with the test basis, sizing factor and maximum allowable stem torque.
A high actuator output number is not automatically a better design. Excess torque can overload the stem, coupling, mounting kit, gearbox or seat system.
Direct Mount Versus Mounting Kit
ISO 5640:2024 provides requirements for metallic mounting kits for part-turn valve and actuator attachments when direct mounting is not practical. Its public scope covers torque-transmitting components, design and environmental corrosion protection.
- State direct mounting or mounting-kit arrangement.
- Provide valve top-flange and actuator bottom-flange designation.
- Provide shaft shape, dimensions, keyway and orientation.
- Define coupling and bracket material, allowable torque and coating.
- Request the final assembly drawing and bill of materials.
Compare XHVALBUTTERFLY’s bare-shaft triple eccentric butterfly valve and worm-gear triple eccentric butterfly valve configurations.
Gearbox RFQ Fields Under ISO 22109:2026
| Gearbox question | Buyer instruction |
|---|---|
| Operation and duty | State manual or automated, on/off or modulating, and emergency requirements |
| Output and direction | Provide required output torque and clockwise or counter-clockwise closing |
| Travel and holding | Define travel, stops, self-locking or braking needs |
| Handwheel and indication | Define rim-pull, chainwheel or extension and local/remote indication |
| Environment | Define enclosure, corrosion, water, dust, temperature and hazardous area |
| Records | Request tests, markings, datasheet and IOM |
Triple-Offset Application Inputs
- Fluid, pressure, differential pressure and temperature.
- Unidirectional or bidirectional shutoff and leakage basis.
- Operating frequency, duty and required cycle time.
- Fail-open, fail-close, fail-in-place or no defined fail action.
- Fire-safe, fugitive-emission, cryogenic, SIL or project requirements.
- Flow direction, pipe orientation and installation envelope.
Copy-Ready RFQ Clause
Supplier shall provide a complete butterfly valve operator package suitable for the stated service and duty. The quotation shall identify the applicable editions of ISO 5211, ISO 22109, ISO 5640 where a mounting kit is used, API 609 or other valve design standard, and the pressure-test basis. Supplier shall submit valve torque data, actuator or gearbox sizing calculation, selected safety factor, maximum allowable valve stem torque, interface drawing, mounting-kit details, fail action, operating time, control accessories, GA drawing, datasheets, IOM documents, and a complete deviation list. Mechanical interface compliance alone shall not be accepted as evidence of actuator sizing.
Final Approval Checklist
- Document the valve service and differential-pressure case.
- Require exact standard editions.
- Obtain valve torque and maximum allowable stem torque.
- Check output at the minimum available supply condition.
- Show the ISO 5211 interface and drive dimensions on the approval drawing.
- Include the mounting kit in torque and corrosion reviews.
- Define fail action, cycle time, controls and manual override.
- Require one assembly responsibility statement and an explicit deviation list.