What is the difference between API 602 and API 600?

API 602 covers compact forged steel gate, globe and check valves typically 4 inch and smaller. API 600 covers larger bolted bonnet steel gate valves, usually cast or forged bodies from 2 inch upward. For instrument, drain and high-pressure branch lines ≤2 inch, API 602 is the governing design standard.

What do RB, FB and SP mean on forged valves?

RB (reduced bore) matches BS 5352 reduced bore or API 602 standard port. FB (full bore) matches BS 5352 standard bore for maximum flow. SP (standard port) is the API 602 standard port designation used on Class 1500 socket-weld valves.

Which standard applies to Y-pattern forged globe valves?

Y-pattern forged globe and check valves for Class 1500 and 2500 are designed per BS 5352 with face-to-face dimensions per MSS SP 84. End connections follow ASME B1.20.1 (NPT), ASME B16.11 (socket-weld) or BS 5352 Annex D (butt-weld).

Forged Steel Gate, Globe & Check Valves — API 602 Engineering Guide

Technical reference · Supreme Valves India · June 2026 · 16 min read

Compact forged steel gate, globe and check valves per API 602, BS 5352 and ASME B16.34 are the workhorse isolation and non-return devices on high-pressure branch lines, instrument manifolds, drain/vent headers and EPC skids from 1/4" through 2". This guide covers standards, bore designations, trim selection, test pressures, and procurement — aligned with the Supreme Valves forged steel range.

1. When to specify API 602 vs API 600

API 602 applies to forged steel gate, globe and check valves in NPS 4 and smaller (this catalogue focuses on 1/4"–2"). Bodies are typically ASTM A105 or alloy forgings; bonnets are compact and suited to threaded, socket-weld and small flanged connections. API 600 covers larger bolted-bonnet gate valves (usually 2"+ in process piping) with cast or heavy forged bodies.

Rule of thumb: Instrument root valves, pump casing drains, steam trap isolation, and high-pressure utility branches ≤2" → API 602/BS 5352 forged. Main line block valves ≥2" on API pipelines → API 600 or API 6D.

2. Applicable standards

Standard	Application
API 602	Gate valve design, compact forged steel
BS 5352	Globe and check design; bore dimensions; Y-pattern
BS 6364	Cryogenic gate and globe
ASME B16.34	Pressure-temperature ratings Class 150–2500
MSS SP 84	Y-pattern globe/check face-to-face
API 598	Shell, seat, back-seat and air seat testing
ASME B16.11	Socket-weld ends and fitting class match
ASME B16.5	Flanged RF ends (125–250 Ra)

3. Bore designations: RB, FB, SP

Code	Meaning	Typical availability
RB	Reduced bore — BS 5352 reduced / API 602 standard port	1/4"–2" all classes
FB	Full bore — BS 5352 standard bore	3/8"–1½" (2" gate RB only on some classes)
SP	Standard port — API 602 (Class 1500 SW)	3/8"–2"

Socket-weld Class 800 RB valves match Class 3000 (Sch.80/XS) fittings; Class 800 FB matches Class 6000 (Sch.160); Class 1500 SP matches Class 9000 (Sch.XXS) per ASME B16.11.

4. Manufacturing programme overview

Gate, globe and check valves are offered across:

Classes: 150, 300, 600, 800, 1500, 2500
Ends: screwed NPT, socket-weld, flanged RF, butt-weld (Y-pattern and high class)
Variants: straight-pattern, Y-pattern (1500/2500), bellows-sealed (800), cryogenic (BS 6364)

For Class 150 flanged valves, flange drilling follows Class 150 while other dimensions follow Class 300; flanges are welded to the forged body.

5. Trim selection (API 602 trim numbers)

Trim	Service	Stem / disc / seat
01	General steam, oil — gate only	410 / 13Cr / 13Cr
05	Erosive, high-cycle — all types	410 HF / Stellite #6 / HF
08	Standard carbon gate/globe/check	410 / 13Cr / HF seat
02, 10	Corrosive — gate	304 or 316 / matching SS
12, 15, 16	Corrosive + erosive	SS stem + HF seating

Body options: A105 (default), LF2 (low temp), F11/F22 (high temp alloy), F304/F316/F347, Monel. Match trim to body P-T limits per ASME B16.34.

6. API 598 hydrostatic test pressures (A105)

Shell test = 1.5× class rating (e.g. 800# → 3000 psi). Gate/globe back-seat and seat closure at class-dependent pressures. Check valves: no back-seat; seat closure only; low-pressure closure at 25% of high-pressure closure test.

Class	Gate shell (psi)	Check seat closure (psi)
150	450	80
800	3000	550
1500	5575	— (Y-pattern per globe/check table)

Full tables: API 602 datasheet §7–8.

7. Y-pattern globe and check (Class 1500 / 2500)

Y-pattern valves use an oblique flow path that reduces pressure drop versus conventional globe valves — important on high-velocity drain and bypass lines. Design per BS 5352; dimensions per MSS SP 84.

Sizes 15–50 mm (NPT, SW, BW)
Scored body-bonnet with graphite gasket; ACME threads; tack-weld in service
Spring-loaded check disc (Nimonic 90 / Inconel X-750) — min. 1 bar ΔP
Steam/drain install: flow over the disc to avoid thermal unseating

Details: Y-pattern Class 1500/2500 product page.

8. Cryogenic and bellows-sealed options

Cryogenic (BS 6364): Austenitic SS body/bonnet (F304/F316), extension column (TP304L/316L), Class 800 standard with Classes 150–1500 also available. Extended bonnet minimises heat ingress to packing.

Bellows-sealed (Class 800): SS316L bellows between stem and bonnet eliminates stem leakage — specify for toxic, vacuum, LH₂/LOₓ adjacent, or fugitive-emission limits. Gate and globe patterns; conforms to BS 5352.

9. Ordering checklist

Valve type (gate / globe / check / Y-pattern / bellows / cryo)
Size and bore (RB / FB / SP)
ASME class and end connection (NPT / SW / RF / BW)
Body material and trim number
Options: IBR, NACE MR-0175, locking, electric actuator, SPL

Example straight-pattern description: 2" Class 800 forged gate, socket-weld, RB, body A105, trim 08, API 602/BS 5352, test API 598.

10. Related products

Need a formal datasheet? Download the complete API 602 technical datasheet or request an RFQ with line list and P&ID tags.