| Applicable Design Standards | The valve should be designed and tested according to the standards required for the installation, such as ISO 4126, ASME Section VIII, API 520, or API 526. | Review the datasheet, design calculations, test procedures, and certificates. Confirm that the stated edition of each standard is applicable to the project. | Standards define essential requirements for sizing, construction, performance, inspection, and documentation. | Critical |
| Pressure Range and Set Pressure | The available set-pressure range must cover the required operating pressure while maintaining adequate operating margin to prevent unnecessary lifting. | Compare the certified set pressure, allowable working pressure, operating pressure, accumulation limits, and applicable code tolerances. | Incorrect pressure selection can cause premature opening, unstable operation, or insufficient overpressure protection. | Critical |
| Capacity and Sizing Data | The supplier should provide certified relieving capacity for the actual fluid, temperature, pressure, and required flow scenario. | Request sizing calculations based on the governing case, including blocked outlet, fire exposure, thermal expansion, gas flow, liquid flow, or steam flow where applicable. | A valve that is mechanically suitable but undersized may not protect the equipment during the governing relief event. | Critical |
| Material Compatibility | Wetted materials, trim, seals, and spring materials should be compatible with the process fluid, concentration, temperature, and corrosion conditions. | Check the material certificate, corrosion-resistance data, seal specification, temperature limits, and compatibility with sour-service requirements where relevant. | Material incompatibility may lead to corrosion, leakage, embrittlement, contamination, or premature failure. | Critical |
| Temperature Capability | The operating and relieving temperatures must fall within the certified limits of the body, trim, spring, gasket, and seat materials. | Verify minimum and maximum operating temperatures, design temperature, heat-tracing requirements, and derating information. | Temperature affects material strength, spring performance, sealing behavior, and discharge capacity. | Critical |
| Connection and Installation Compatibility | Inlet and outlet connections must match the project piping specification, including nominal size, pressure class, flange standard, thread type, or weld-end requirements. | Compare dimensional drawings with the piping layout and verify face-to-face dimensions, orientation, reaction loads, and discharge-piping requirements. | Connection mismatches can cause installation delays, leakage, excessive loads, or unsafe discharge arrangements. | High |
| Backpressure Performance | The valve should be suitable for the expected built-up and superimposed backpressure, with balanced or pilot-operated construction considered when required. | Request backpressure limits, capacity correction factors, stability data, and guidance for connected headers or closed discharge systems. | Backpressure can change opening behavior, reduce capacity, and create chatter or unstable operation. | Critical |
| Leakage and Seat Tightness | The required seat-tightness level should be stated using the applicable test standard and acceptance class for the service. | Review shop test records, seat-leakage acceptance criteria, test medium, test pressure, and any soft-seat temperature limitations. | Low leakage helps protect product quality, reduce emissions, and maintain process efficiency. | High |
| Certification and Traceability | Each supplied valve should have traceable identification linked to material certificates, inspection records, calibration records, and final test results. | Confirm serial-number traceability, material test certificates, inspection plans, pressure-test reports, calibration certificates, and certificate-of-conformity documentation. | Traceability supports regulatory compliance, quality audits, maintenance planning, and failure investigations. | High |
| Regulatory Compliance | For regulated markets, the valve and quality system should meet applicable requirements such as the EU Pressure Equipment Directive 2014/68/EU or local pressure-equipment rules. | Check conformity assessment documents, notified-body involvement where required, marking requirements, declarations, and market-specific technical files. | Regulatory gaps may prevent customs clearance, commissioning, or legal operation in the destination market. | Critical |
| Sour-Service and Special-Service Suitability | For wet hydrogen sulfide environments, materials and manufacturing controls should meet the applicable requirements of NACE MR0175/ISO 15156. | Verify hardness controls, material restrictions, heat-treatment records, sour-service declarations, and process-fluid composition limits. | Sour service can create sulfide stress cracking and other failure mechanisms in unsuitable materials. | Critical |
| Testing and Quality Control | The quality plan should cover dimensional inspection, pressure testing, set-pressure testing, seat-leakage testing, and final visual inspection. | Request the inspection and test plan, hold-point schedule, calibration status, nonconformance process, and independent inspection options. | A documented quality process reduces manufacturing variation and improves confidence in delivered performance. | High |
| Maintenance and Spare Parts | The design should support practical inspection and repair, with replacement seats, gaskets, springs, and trim available for the expected service life. | Review maintenance manuals, recommended inspection intervals, overhaul procedures, spare-parts lists, and field-service capabilities. | Accessible maintenance reduces downtime and helps preserve certified relief performance. | High |
| Documentation Quality | The technical package should be complete, consistent, and delivered in the buyer’s required language and document format. | Assess datasheets, drawings, manuals, calculations, certificates, test reports, preservation instructions, and document revision control. | Complete documentation simplifies approval, installation, commissioning, operation, and future audits. | High |
| Delivery and Export Readiness | The supplier should provide a confirmed production schedule, export packing, shipping documents, and preservation suitable for the transport route. | Verify manufacturing lead time, inspection dates, packing method, country-of-origin documents, customs information, and Incoterms. | Reliable logistics reduce project delays and protect the valve during international transportation and storage. | High |
| Technical Support and Communication | The supplier should provide qualified engineering support for sizing, application review, installation, troubleshooting, and after-sales service. | Evaluate response procedures, engineering contact availability, calculation support, training resources, service coverage, and escalation routes. | Fast and accurate technical support helps prevent selection errors and shortens problem-resolution time. | Medium |
| Total Cost of Ownership | Compare purchase price together with testing, certification, freight, installation, maintenance, spare parts, energy loss, and expected replacement costs. | Use a lifecycle-cost worksheet and compare equivalent specifications rather than comparing purchase prices alone. | The lowest initial price may result in higher operating costs, more frequent maintenance, or greater downtime. | High |