These are real questions we hear from contractors, EPC buyers and plant engineers — asked by email, on calls, and in RFQ clarifications. We have turned the most common ones into short technical answers. If your question is not here, ask us directly; the best ones become future posts.
1. “The spec says API 607. The vendor offers ISO 10497. Is that acceptable?”
Usually yes — ISO 10497 is the international twin of API 607 and many certificates cover both. But acceptance belongs to the spec owner: request a deviation approval in writing, attaching the fire-test certificate showing the tested size/class range covers your valves.
2. “Do I need NACE compliance for fire-water service?”
No — NACE MR0175 addresses sulfide stress cracking in sour hydrocarbon service. Fire-water ring mains need fire-safe design and often FM approval, not NACE. Mixing these up adds cost with no benefit.
3. “What is the difference between a knife gate and a wedge gate valve?”
A knife gate has a thin, sharp-edged gate that cuts through slurries, pulp and powders — ANSI-light bodies, mostly Class 150 equivalents, bidirectional options. A wedge gate valve per API 600 is a full-pressure-class isolation valve for clean fluids. They are not interchangeable.
4. “Can you supply valves without a brand requirement?”
Yes — most industrial projects are specified by standard, not by brand: “API 602 Class 800, A105, welded bonnet” can be met by many qualified manufacturers. We quote per specification with full material certs (EN 10204 3.1), test reports and, where required, third-party inspection.
5. “What documentation should come with an industrial valve order?”
As a minimum: material test certificates (3.1), API 598 or equivalent test reports, and the marking per MSS SP-25. Depending on service: fire-test certs (API 607), cryogenic type-test (BS 6364), fugitive-emission cert (ISO 15848-1), NACE compliance statement, PED CE marking for EU destinations, and IOM manuals.
6. “Are stainless valves always the safe choice?”
No. 316 handles most corrosives but chlorides at temperature can pit it — duplex (F51/F55) exists for that reason. And stainless costs more while offering less strength than alloy steel at high temperature. Match the material to the fluid, don’t default to it. See our stainless steel valve range.
7. “Electric or pneumatic actuator?”
Pneumatic wins on speed, fail-safe spring action and hazardous-area simplicity when plant air exists. Electric wins on precise positioning, no air infrastructure, and remote sites. Details on our actuation & automation page.
Four More Questions That Come Up Constantly
9. “The drawing says Class 150 but the design pressure is 250 psi. Is that a problem?”
Possibly, and it depends on temperature. Pressure class is not a pressure — it is a rating curve that falls as temperature rises. A Class 150 valve handles well above 150 psi at ambient and considerably less at elevated temperature. Check the pressure–temperature table for the actual body material at the actual design temperature, not the class number on the drawing.
10. “Can we substitute a different manufacturer if the specification names one?”
Usually yes, through a substitution submittal that demonstrates equivalence on the points the specification actually cares about: standard and edition, pressure class, materials, seat and leakage class, certifications and end connections. Substitutions are rejected far more often for incomplete documentation than for genuine technical inferiority.
11. “Why is the lead time different for two identical valves?”
Because one is in stock and the other is a build. Certifications also drive schedule — a witnessed test, a 3.2 certificate or a fire-test document that must be reissued for a specific size can add weeks that have nothing to do with manufacturing capacity.
12. “Who is responsible if the valve does not fit?”
Whoever specified the face-to-face standard, or failed to. Dimensional standards differ between flanged, grooved and wafer patterns, and between ASME and EN practice. Confirm the face-to-face standard in the quotation and check it against the piping drawing before release — this is a five-minute check that prevents a site-wide problem.
How to Phrase an RFQ So the Answers Are Comparable
Most of the confusion above disappears when the enquiry is specific. A request that states size, class, design pressure and temperature, body and trim materials, end connections with the governing dimensional standard, seat leakage acceptance, required certifications, documentation type under EN 10204, and required delivery date will come back with quotations that can actually be compared line by line. Anything less and the comparison becomes guesswork dressed up as procurement.
8. “Why do you not publish prices for industrial valves?”
Because two “identical” line items can differ 40% depending on trim, bonnet, documentation and origin — a published price would mislead you. We quote against your datasheet, project by project, typically within 24–48 hours.
Working on a valve package for Canada, the US, Europe, the Middle East or Türkiye? Send your inquiry to ValveAtlas — technical review included, no obligation.
