Forged valve RFQ specification checklist

1. Identify each valve line

Give every valve a line number or tag. State quantity, valve family and construction on the same row. “Valve, 1 inch, Class 800” leaves the function, pattern and ends unresolved.

For gate valves, state wedge and bonnet construction. For globe valves, state T-pattern or Y-pattern. For check valves, state piston-lift or swing. For ball valves, state floating or trunnion design where controlled, full or reduced bore, and operation.

2. State the process conditions

Provide medium and composition, including contaminants and solids. List design pressure and temperature as independent values, then normal operating pressure and temperature. Add minimum design-metal temperature and vacuum conditions where applicable.

For globe-valve regulation, provide minimum, normal and maximum flow with inlet and outlet pressure, temperature, density, viscosity and phase. For check valves, provide the same flow range, line orientation, available differential and transient or pump-trip data.

• Design pressure and design temperature
• Operating pressure and temperature range
• Minimum design-metal temperature
• Fluid name, composition, concentration, solids and phase
• Differential pressure at closure or maximum shut-off differential
• Operating and cycling frequency
• Flow cases where sizing or dynamic behaviour matters

3. Fix the piping interfaces

State NPS or DN and identify the dimensional system. Add pressure Class or PN only after the governing rating basis is known. Name NPT, SW, BW, RF, RTJ or FF and the applicable interface standard.

For butt-weld ends, include pipe outside diameter, schedule or wall thickness, bore and bevel. For flanges, include standard, Class or PN, facing and any ring-joint designation. For replacement valves, add measured end-to-end and available installation envelope.

4. Describe materials by component

Specify body and bonnet material using full material specification and grade. Then list closure member, seat surfaces, stem, backseat, ball, soft seats, packing, gaskets and bolting as applicable. A single body grade copied into a “material” cell is not a bill of materials.

State hardfacing and surface-treatment requirements separately. If the supplier may propose materials, write “supplier to propose for stated service” and require a completed material schedule with the quotation.

5. Separate the standards by purpose

List the valve product standard and edition. Then list the design and rating basis, face-to-face or end-to-end basis, connection standards and inspection/test standard. Add the governing piping code and project valve specification.

A list such as “API/ASME compliant” cannot be inspected. Each reference must have a purpose. If the project allows a later edition or equivalent standard, define the approval route for deviations.

• Product standard: for example API 602 for an in-scope gate, globe or check valve
• Valve design and pressure-temperature basis: for example ASME B16.34 where applicable
• Ends: ASME B16.5, B16.25, B1.20.1, EN 1092-1 or another stated basis
• Dimensions: project-required face-to-face or approved manufacturer drawing
• Inspection and pressure testing: named standard, edition and additions

6. Set inspection and document scope before order

State required shell and closure tests, leakage acceptance, supplementary examinations and witness points. Add NDE, PMI, hardness, impact, ferrite, coating or fugitive-emission requirements only where the project needs them, with methods and acceptance criteria.

Name the material-certificate scope: EN 10204 type 3.1, type 3.2 or another basis. A type number without the parts covered can produce an incomplete document set. List the pressure-containing parts, trim or bolting covered, and request valve pressure-test and NDE reports separately.

7. Compare quotations line by line

Require the supplier to return the valve list with every field completed and every deviation identified. Datasheet, general-arrangement drawing, pressure-temperature limits and material schedule should agree with the commercial line item.

Do not compare unit prices until technical exceptions are visible. A different pattern, seat material, flange facing, certificate scope or test can explain a price difference and can also make the valve unusable for the intended line.