Class 800 vs Class 1500 Forged Valves: When to Specify
Technical guide · Supreme Valves India · Updated 2026-10-28
Direct answer: For small-bore forged gate, globe and check valves with socket-weld or NPT ends, Class 800 is the default rating on most India and Middle East RFQs. Specify Class 1500 only when the piping class or design conditions require it — not as a casual upgrade.
Forged A105 Class 800 OS&Y gates are among the highest-frequency lines in our BOQ archive, especially SW and FNPT ends.
Two different product families
| Forged Class 800 / 1500 | Cast Class 150 / 300 | |
|---|---|---|
| Typical standard | API 602 / BS 5352 | API 600 / BS 1414 |
| Ends | SW, NPT, SW×NPT, BW | Flanged RF / RTJ |
| Sizes | Small bore (often ≤2") | 2" and above common |
| BOQ pattern | A105N CL800 SW OS&Y | WCB CL150 RF OS&Y |
Why Class 800 dominates SW/NPT RFQs
Instrument take-offs, steam tracing manifolds, drains and utility branches are usually socket welded or screwed. The forged Class 800 rating covers typical design pressures for those branches without jumping to flanged Class 300/600 hardware. Saudi packages often list bolted-bonnet OS&Y A105 Class 800 SW and NPT gates in the same inquiry as cast Class 150 WCB gates for larger lines.
When Class 1500 shows up
- Owner piping class explicitly Class 1500
- High-pressure steam or hydrocarbon small bore
- Some ball-valve BOQs in stainless F316 Class 800/1500 screwed service
Class 1500 costs more and may change bore and face-to-face. Do not substitute 1500 for 800 (or vice versa) without design approval.
Ends and bore on the same RFQ
- SW ASME B16.11 — permanent process small bore
- NPT — utility and instrument
- Mixed SW×NPT — common on manifolds
- Full vs reduced port — state FB or RB for balls; gates follow API 602 port rules
RFQ checklist
- Class 800 or 1500 (from piping class)
- Body A105 / A105N / F316 / F11 etc.
- Ends SW / NPT / BW
- Trim #8 or Stellite scope
- IBR yes/no for steam
Start with the A105 Class 800 gate RFQ pattern and add Class 1500 only where the isometric demands it.
Frequently asked questions
Why are screwed and SW forged valves usually Class 800?
Compact forged valves for threaded and socket-weld ends are commonly rated Class 800 under API 602 practice. Flanged cast valves on the same plot plan are often Class 150 or 300 — different product families.
When do I need Class 1500 instead of 800?
When the piping class, design pressure/temperature or owner spec requires Class 1500. Do not upsize class without a design basis — wall thickness, face-to-face and cost all change.
Can Class 800 forged gates replace Class 150 flanged gates?
No. Ends, face-to-face and installation differ. Use forged Class 800 on small-bore SW/NPT branches; use flanged cast gates on main process lines as designed.