How to Write a Valve Procurement Specification (Data Sheet, RFQ)
Updated: Aug 24
What Should a Valve Procurement Specification Include?
A complete valve procurement specification should define the service conditions, valve type and size, pressure rating, materials, end connections, testing, inspection, documentation, actuator requirements, delivery terms, and permitted deviations. Put item-specific requirements on the data sheet and common requirements in the technical specification so every supplier quotes the same scope.
Purpose of a Procurement Specification
The procurement specification serves multiple purposes: technical communication (clearly communicates your requirements to potential suppliers); bid evaluation (provides a basis for comparing technical proposals); quality assurance (specifies the standards, tests, and inspections that the valve must meet); and contract enforcement (serves as part of the purchase order, so non-compliance can be rejected). A good specification is clear, complete, and unambiguous.
The specification typically consists of: a valve data sheet (technical details for each valve type); a general technical specification (applicable standards, material requirements, testing requirements, documentation requirements); and commercial terms (delivery, warranty, inspection, etc.). For large projects, the specification may be part of a larger piping material specification (PMS) or equipment specification.
Valve Data Sheet Preparation
The valve data sheet is the core technical document. It should include: valve tag number (unique identifier for each valve in the plant); valve type (gate, globe, ball, butterfly, check, etc.); size (NPS or DN); pressure class (Class or PN); end connection (flanged, threaded, welded, etc.); body material (ASTM grade); trim material (seat, disc, wedge material); seat type (soft-seated, metal-seated); operator type (handwheel, gear, actuator type); and special requirements (NACE, fire-safe, cryogenic, etc.).
Many companies use standard data sheet formats (e.g., API 6D data sheet for pipeline valves, or company-specific forms). The data sheet should be filled out completely—do not leave blanks. If a parameter is not applicable, write 'N/A' or 'As per manufacturer standard.' Incomplete data sheets lead to guesswork by the supplier, which often results in mismatched expectations.
Key Technical Clauses
A good specification includes the following technical clauses: scope (what is included: valve, actuator, accessories, spare parts); applicable standards (material standards, dimension standards, test standards, NACE, etc.); material and manufacturing (casting or forging method, welding procedure, heat treatment); pressure-temperature rating (ASME B16.34 or manufacturer's standard); and dimensions (face-to-face per ASME B16.10, end-to-end for welded ends).
Additional clauses: testing and inspection (shell test, seat test, pneumatic test, NDT requirements, witness points); surface preparation and coating (cleanliness standard, coating type and thickness, color code); marking (ASME B16.34 marking requirements, additional project marking); documentation (drawings, calculations, test reports, MTRs, O&M manuals); and packing, preservation, and shipping (preservation method, box marking, certificate of compliance).
Material Selection Criteria in Specifications
The specification must clearly state material requirements: body and bonnet material (ASTM grade, heat treatment condition); trim material (seat, disc, wedge, stem—often different from body material); bonnet bolting (ASTM A193/A194 or equivalent); and gaskets and packing (material, temperature rating). If NACE MR0175/ISO 15156 compliance is required (for sour service), state it explicitly and specify the hardness limits.
For critical service, require material traceability (heat number stamping on all pressure-containing parts) and Mill Test Reports (MTRs) per EN 10204 Type 3.1 or 3.2. For cryogenic service, specify low-temperature impact testing (Charpy V-notch) requirements. For high-temperature service, specify creep rupture strength data requirements.
Quality Assurance and Inspection Clauses
Quality assurance clauses protect the buyer. Key clauses include: manufacturer qualification (ISO 9001 certification, API 6D monogram if applicable); inspection and test plan (ITP) (defines hold points where the buyer or third-party inspector must witness tests); witness points (W) vs hold points (H) (for hold points, the manufacturer cannot proceed without inspector approval); and test reports (format, language, approval signatures).
Specify which tests are required: standard production tests (shell, seat, backseat); supplementary tests (fire-safe test, cryogenic test, low-pressure gas seat test, static electricity test); and NDT (radiography, ultrasonic, magnetic particle, liquid penetrant). For critical valves, specify third-party inspection (TPI) by a recognized agency (e.g., TUV, DNV, BV, ABS).
Commercial Considerations in the Specification
While the specification is primarily technical, some commercial aspects should be included: delivery schedule (required delivery date, partial shipment allowed or not); warranty (period, what is covered, what is excluded); spare parts (mandatory spare parts list, recommended spare parts); and training (if the buyer requires training on valve maintenance or actuator calibration).
Also specify: language of documentation (English is standard for international projects); units (metric or imperial, or dual); and export packing requirements (seaworthy packing, preservation for long-term storage). These may seem minor, but they frequently cause delays and additional costs if not specified upfront.
Common Specification Mistakes to Avoid
Mistakes in procurement specifications are common and costly. Avoid these: copying a previous specification without updating (project requirements differ; what worked for a refinery may not work for a chemical plant); being too vague ('manufacturer standard' is not a specification—always state the required standard); and over-specifying (specifying exotic materials or tests that are not needed increases cost and lead time).
Other mistakes include failing to name the applicable standard edition, leaving flow direction unclear for unidirectional valves, and omitting actuator requirements such as failure position, signal type, available power, and operating time. Confirm the project-required edition at the time of purchase; for example, ASME lists B16.34-2025 as the current published edition.
Evaluating Supplier Quotations Against the Specification
Once the RFQ is issued, you will receive quotations from multiple suppliers. Evaluation should be based on: technical compliance (does the valve meet all specification requirements?); delivery (can the supplier deliver on time?); price (total cost, including options and spare parts); and track record (has the supplier delivered similar valves successfully?).
A common pitfall is selecting the lowest-price bid without verifying technical compliance. If a supplier's quotation deviates from the specification, you must evaluate the deviation: is it acceptable (e.g., better than specified), neutral, or unacceptable? All unacceptable deviations must be resolved before awarding the order. A 'bid comparison matrix' that lists each supplier's compliance side-by-side is a useful tool.
Post-Award Activities
After awarding the order, the work is not done. Post-award activities include: review and approval of drawings and calculations (the supplier submits drawings; the buyer reviews and approves before manufacturing starts); inspection (witness tests per the ITP); and documentation review (test reports, MTRs, O&M manuals). The purchase order should specify the timeline for submitting these documents.
Also, consider a pre-inspection meeting (PIM) with the manufacturer to review the specification, clarify any ambiguities, and confirm the inspection schedule. For critical valves, a pre-manufacturing inspection (PMI) of raw materials may be specified to verify material chemistry before manufacturing starts.
Conclusion
Writing a valve procurement specification is a detailed but essential task. A good specification prevents misunderstandings, ensures quality, and provides a basis for bid evaluation and contract enforcement. Key elements include: a complete valve data sheet; clear technical clauses (materials, standards, testing); quality assurance requirements (inspection, documentation); and commercial terms (delivery, warranty). Avoid common mistakes such as being too vague or over-specifying. By investing time in the specification upfront, you save time, money, and headaches during manufacturing, inspection, and installation.
Frequently Asked Questions
What is the difference between a data sheet and a specification?
The data sheet is a form that captures the technical parameters for each valve (size, type, material, etc.). The specification is a document that states the general technical requirements (standards, tests, quality) that apply to all valves in the scope.
Should I specify 'or equal' in my specification?
'Or equal' allows the supplier to propose an alternative that is equal or better. However, it can lead to disputes over what is 'equal.' It is better to specify exactly what you need, or list approved manufacturers if you want to restrict options.
How detailed should I be for non-critical valves?
For non-critical, low-pressure, low-temperature valves (e.g., cooling water, drain), a simpler specification is acceptable. But always specify the minimum requirements: material, pressure class, end connection, and testing.
Can I reuse a previous project's specification?
You can, but you must review and update it. Project conditions (fluid, temperature, pressure, standards) differ. At minimum, verify that all referenced standard editions are current and that the material selections are appropriate for the new service.
Official Standards References
Contact Us
For inquiries about our valve products, custom solutions, or technical support, please reach out to our team. We can provide detailed data sheets, technical proposals, and documentation that meet your project specifications.
Ted Wang
Wechat/Whatsapp: +86 18267833722
Email: sales@wofervalve.com
Web: www.wofervalve.com
Wenzhou Wofer Valve Co., Ltd.
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