| 1 | Design Standard | API 609 Category B or EN 593 | These standards define key requirements for butterfly-valve design, dimensions, pressure-temperature ratings, testing, and performance. | Which design standard is used, and can the manufacturer provide the latest design and compliance documentation? |
| 2 | Pressure and Size Range | Common configurations include DN50–DN2000 and PN10–PN40 or ASME Class 150–300 | The available size and pressure range must match the pipeline, operating pressure, flange dimensions, and system expansion requirements. | What are the maximum nominal size, pressure class, face-to-face dimensions, and allowable operating temperature? |
| 3 | Pressure Testing | Testing according to API 598 or ISO 5208 | Standardized shell and seat tests help verify pressure integrity and shut-off performance before shipment. | Are shell, seat, functional, and optional fugitive-emission tests included in the inspection and test plan? |
| 4 | Materials and Corrosion Resistance | Ductile iron, carbon steel, stainless steel, or duplex stainless steel selected according to the medium | Valve-body, disc, shaft, and seat materials must withstand corrosion, erosion, temperature, and chemical compatibility requirements. | Can the manufacturer provide material certificates, corrosion-resistance data, coating specifications, and trim options? |
| 5 | Sealing Performance | Resilient or metal seat options with a stated leakage class and test method | Double eccentric geometry reduces rubbing between the disc and seat, while the selected seat design determines shut-off reliability and service life. | What leakage rate is guaranteed, which seat materials are available, and how is seat wear or replacement managed? |
| 6 | Actuation and Automation | ISO 5211-compatible mounting with manual, pneumatic, electric, or hydraulic actuation | Correct actuator sizing is essential for breakaway torque, operating speed, emergency operation, and integration with the control system. | Will the supplier provide torque calculations, actuator sizing, position feedback, solenoid valves, and fail-safe options? |
| 7 | Quality, Service, and Documentation | Documented quality system, traceability, inspection records, spare-parts support, and lifecycle service | Reliable documentation and after-sales support reduce installation delays, simplify audits, and improve long-term maintenance planning. | Can the manufacturer supply drawings, certificates, inspection reports, operating manuals, spare-part lists, and warranty terms? |