Gate Valves

Frequently Asked Questions

API 600 vs API 603 — when do I specify which?

API 600 is the standard for bolted-bonnet steel gate valves in general petroleum and petrochemical service — carbon steel and alloy steel bodies, typical for oil & gas, refining, and power. API 603 is for corrosion-resistant stainless-steel gate valves — used in chemical, pharmaceutical, food, and any service where the process media attacks carbon steel. If you're specifying for offshore, petrochemical, or refining service, API 600 is almost always right. If the medium is corrosive or purity-critical, API 603 in stainless.

Solid wedge, flexible wedge, or parallel-slide?

Solid wedge: general-purpose, most common, cost-effective — default unless you have a reason to deviate. Flexible wedge: used where the body will see thermal expansion/contraction (steam service, process temperature swings) — the small slot in the wedge allows slight deformation without binding. Parallel-slide: high-temperature steam (power-plant boiler isolation), where the sealing surfaces slide parallel and are energised by line pressure. Knife-gate: slurry, fibrous materials, high-solids — not a true gate valve in the API 600 sense, different design family.

Pressure-seal bonnet — when is that needed?

Pressure-seal bonnet design is specified for high-pressure service, typically ASME 900 class and above, and particularly for high-temperature steam in power generation. The line pressure energises the bonnet gasket, meaning the seal gets tighter as pressure rises — far more reliable than a bolted bonnet at 1500# or 2500# class. Cost is higher than bolted-bonnet but the design is standard practice for main steam isolation, HP feedwater, and pipeline service above 1500#.

Can you supply gate valves to Aramco, ADNOC, or QatarEnergy approved vendor lists?

Yes — a subset of our MSME partner network holds these approvals, including API 600 monograms. Approval status for specific end clients and engineering contractors is confirmed per line item in the formal quote. If your end-client has a specific AVL (Approved Vendor List) that does not currently include our proposed manufacturer, we can initiate the qualification process — typically 6–12 months for a new listing, but existing approvals are the fast path.

Typical lead time for API 600 gate valves?

6–8" class 150/300 in carbon steel: 4–6 weeks manufacturing. Larger bores (12"+) or higher pressure classes (600–2500): 10–16 weeks. Specialty metallurgy (chrome-moly, nickel alloys, duplex): add 3–4 weeks. The critical path is usually casting lead time for the body — forged bodies are faster for specific sizes but more expensive.

Do you provide API 598 hydrostatic and seat leakage test certificates?

Yes — API 598 testing is standard on every gate valve shipped. Shell hydro is performed at 1.5× design pressure, with water as the test medium, held for the standard time per size class. Seat leakage testing is performed at 110% of design pressure with the valve closed, both seats tested independently; acceptable leakage per API 598 tables (typically 0 visible drops for soft-seated and a measured rate for metal-seated). Signed and witnessed test reports are shipped with the goods.