| Application and Valve Type | Suitability of globe, rotary, butterfly, ball, or eccentric plug valve for the service. | Selection should match flow behavior, shutoff duty, pressure drop, temperature, and required control range. | Sizing sheet, process data review, valve selection calculation, and application references. | The wrong valve design can cause unstable control, excessive noise, cavitation, or premature wear. |
| Flow Capacity and Sizing | Published Cv or Kv values, operating range, and sizing methodology. | Calculations should use recognized control-valve sizing practices, such as IEC 60534-2-1 or ISA 75.01.01. | Signed sizing calculation, flow coefficient curves, and predicted operating point. | Correct sizing improves controllability and prevents oversized valves from operating near the seat. |
| Pressure and Temperature Rating | Body class, pressure rating, temperature limits, and derating requirements. | Ratings must comply with the applicable design code, such as ASME B16.34, EN 12516, or the project specification. | Pressure-temperature tables, design calculations, and material certificates. | Operating beyond the allowable envelope can create leakage, deformation, or loss of containment. |
| Materials and Corrosion Resistance | Compatibility of body, trim, seat, gasket, and packing materials with the process fluid. | Material selection should consider corrosion, erosion, chloride content, hydrogen service, and temperature. | Material certificates, trim specifications, corrosion assessment, and chemical compatibility data. | Suitable materials extend service life and reduce unplanned maintenance. |
| Leakage Performance | Seat leakage class and fugitive-emission performance. | Verify the specified shutoff class under the actual test pressure; IEC 60534-4 and ISO 15848-1 are commonly referenced. | Factory test reports, leakage classification, packing test data, and inspection records. | Low leakage supports safety, environmental compliance, and process efficiency. |
| Control Accuracy and Rangeability | Inherent flow characteristic, hysteresis, dead band, repeatability, and usable rangeability. | Performance should be validated at the intended operating range rather than only at the nominal flow point. | Performance curves, calibration records, and control-loop test results. | Accurate modulation helps maintain stable pressure, temperature, level, or flow. |
| Actuator and Positioner Integration | Actuator torque or thrust, fail position, air supply, response time, and position feedback. | The actuator must provide adequate margin for maximum differential pressure and emergency operating requirements. | Actuator sizing calculation, instrument data sheet, fail-action test, and calibration report. | Proper integration ensures dependable movement and a predictable safe position. |
| Noise, Vibration, and Cavitation Control | Predicted sound pressure, cavitation index, flashing risk, and vibration mitigation. | Assessment should follow recognized methods such as IEC 60534-8 series and use actual process conditions. | Noise calculation, anti-cavitation trim proposal, acoustic data, and field references. | Managing dynamic effects protects equipment, operators, piping, and nearby instrumentation. |
| Quality Management | Manufacturing controls, traceability, inspection planning, and nonconformance handling. | A current ISO 9001 quality management certification is a useful baseline, subject to customer requirements. | Valid certificate, quality manual, inspection and test plan, and audit results. | Consistent processes reduce variation between production batches. |
| Testing and Inspection | Shell tests, seat leakage tests, functional tests, dimensional inspection, and optional witness points. | Testing should follow the purchase specification and applicable standards, including API 598 or ISO 5208 where relevant. | Completed test dossier, calibrated instrument records, inspection release note, and traceability documents. | Documented verification confirms that supplied equipment matches the approved design. |
| Safety and Industry Compliance | Compliance with pressure equipment, hazardous-area, fire-safe, and functional-safety requirements. | Certificates must match the exact product configuration and the regulations of the installation location. | Conformity declarations, hazardous-area certificates, fire-test reports, and safety documentation. | Correct certification supports legal operation and reduces project approval risk. |
| Customization and Engineering Support | Ability to provide special trims, low-temperature designs, severe-service solutions, and technical calculations. | Supplier should demonstrate documented engineering capability for the stated process conditions. | Technical proposal, drawings, calculations, design review records, and application case studies. | Strong engineering support is especially important for critical or nonstandard services. |
| Delivery Capability | Production capacity, manufacturing lead time, export experience, packaging, and logistics coordination. | Supplier commitments should include realistic milestones for drawing approval, production, testing, and shipment. | Manufacturing schedule, capacity statement, delivery references, packing specification, and shipping documents. | Reliable delivery reduces installation delays and project schedule exposure. |
| After-Sales Service and Spare Parts | Availability of replacement trim, packing, gaskets, actuators, positioners, manuals, and field support. | Parts identification should be supported by drawings, bill of materials, and durable equipment records. | Spare-parts list, service response procedure, maintenance manuals, and warranty terms. | Accessible support lowers downtime and simplifies long-term maintenance. |
| Total Cost of Ownership | Purchase price, installation, energy consumption, maintenance, spare parts, downtime, and disposal costs. | Compare lifecycle cost over the planned operating period, not only the initial quotation. | Lifecycle cost model, maintenance history, energy estimate, warranty, and service-rate schedule. | The lowest purchase price may not provide the lowest operational cost. |