API 602

Covers — compact forged (and some cast) steel gate, globe, and check valves in sizes DN 8–100 (NPS ¼–4), Classes 150, 300, 600, 800, and 1500, with threaded, socket-weld, butt-weld, and flanged ends.

Does NOT cover (exclusions) — the following are governed elsewhere:

• Full-size heavy-duty gate valves → API 600.
• Corrosion-resistant thinner-wall gate valves → API 603.
• Ratings basis → ASME B16.34; testing → API 598.

API 602 is the small-bore forged-valve standard; use API 600 above NPS 4 heavy-duty duty.

API 602 sets minimum requirements for compact steel valves:

• Materials — forged (or cast) steel bodies rated to B16.34 with defined trim.
• Design — compact bolted or welded bonnet, bore options, and end connections for small-bore service.
• Examination & Testing — shell and seat testing per API 598.

API 602 covers compact forged-steel gate, globe, and check valves in NPS 4 and smaller. Forged construction gives robust small-bore valves for vents, drains, instrument roots, and utility connections in refinery and process plants.

It is the small-bore companion to API 600 and shares the B16.34 rating basis and API 598 testing. Class options run from 150 to 1500.

Engineering Note: On small-bore branches, socket-weld API 602 valves reduce leak paths versus threaded — prefer them for hydrocarbon service.