When buyers compare industrial valve quotations, the lowest price is often the easiest number to read and the hardest number to trust. A quotation for a ball valve, gate valve, check valve, globe valve, plug valve, or butterfly valve is only comparable when the inspection and document scope is clear.
For export projects, maintenance shutdowns, EPC packages, and distributor stock programs, the RFQ should not only ask for size, class, material, and end connection. It should also state what test report, material certificate, drawing, and deviation list the supplier must provide.
Quick Verdict
If the valve will be used in oil and gas, chemical, steam, water treatment, power, mining, or other industrial service, buyers should request the test and document package before price comparison.
| Document or test item | What the buyer should request | Why it matters |
|---|---|---|
| API 598 or project test basis | Shell test, seat test, backseat test where applicable, and test medium | Different test assumptions can change acceptance and cost. |
| MTC / EN 10204 certificate | Material certificate type, heat number traceability, and pressure-retaining parts covered | Prevents material ambiguity after the order is placed. |
| GA drawing | Face-to-face, flange drilling, end connection, operator, and weight | Confirms the valve will fit the line and actuator package. |
| Deviation list | Any change from RFQ standard, material, trim, testing, coating, or documents | Makes hidden assumptions visible before purchase order approval. |
Why This Topic Matters Now
Recent RFQs are becoming more document-sensitive. Buyers may ask for API, ASME, ISO, EN, NACE, fugitive-emission, fire-safe, or project-specific evidence in the same inquiry. If the quotation only says “standard test included,” the buyer may not know whether the supplier is quoting the same scope.
- API 608 or API 6D ball valves.
- API 600 gate valves.
- API 594 check valves.
- Globe valves for throttling or isolation duty.
- Plug valves for quarter-turn isolation.
- API 609 butterfly valves.
API 598: What Buyers Should Clarify
API 598 is commonly referenced for valve inspection and pressure testing. In practical RFQ language, buyers should avoid writing only “API 598 test required” and then stopping there.
Valve shall be pressure tested to API 598 unless the project specification states otherwise. Supplier shall confirm shell test, seat test, backseat test where applicable, test medium, test duration, acceptance basis, and whether witnessed inspection is included or optional.
| Common RFQ gap | Possible consequence |
|---|---|
| Test basis is mentioned but no report is requested | Buyer may receive a quotation without a usable test document. |
| Witness inspection is not stated | Supplier may price normal factory testing only. |
| Project standard conflicts with API 598 | Supplier may quote the easier assumption unless deviations are listed. |
MTC and Traceability
- Required certificate type, such as EN 10204 3.1 when applicable.
- Whether pressure-retaining body, bonnet, cover, and end parts need heat number traceability.
- Trim material and seat material confirmation.
- Whether NACE / sour service requirements apply.
- Whether low-temperature impact test evidence is required.
For general sourcing, buyers can review 91探花’s Ball Valve, Gate Valve, Check Valve, and Globe Valve product ranges before narrowing the document scope.
Drawings and Dimensions
- General arrangement drawing.
- Face-to-face or end-to-end dimension.
- Flange standard and drilling.
- Bore, port, or flow direction where relevant.
- Operator type: handwheel, lever, gear, pneumatic actuator, electric actuator, or bare stem.
- Weight and center of gravity for larger valves.
- Mounting interface if automation is included.
For butterfly-valve packages, internal links can guide technical review to the focused 91探花BUTTERFLY range: , , and .
Deviation Lists
| Area | Examples of deviations to disclose |
|---|---|
| Standard basis | API, ASME, ISO, EN, or project standard differences |
| Material | Body, bonnet, trim, seat, gasket, packing, bolting |
| Testing | Test basis, medium, duration, witnessed inspection, special tests |
| Dimensions | Face-to-face, flange drilling, bore, operator envelope |
| Documents | MTC, test report, drawing, IOM, certificate availability |
Sample RFQ Document Clause
Supplier shall quote the valve with the applicable valve design standard, pressure-temperature rating basis, API 598 pressure test scope, MTC requirement, GA drawing, IOM, packing list, and deviation list. The quotation shall state whether witnessed inspection, third-party inspection, special coating, low-temperature test, fire-safe evidence, fugitive-emission evidence, or NACE compliance is included, optional, or not available for the offered construction.
Final Buyer Checklist
- Valve type, size, class, material, and end connection.
- Applicable product standard and pressure-temperature rating basis.
- API 598 or project pressure test scope.
- MTC type and material traceability requirement.
- Drawing and dimension package.
- Inspection plan and witness requirement.
- Deviation list.
- Final document package required before shipment.
A clear RFQ does not slow the purchase process. It reduces rework, prevents false low pricing, and gives the buyer a stronger technical record for approval.