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- API 609 — Butterfly Valves — Double Flanged, Lug and Wafer Types
- API 609 — Butterfly Valves — Double Flanged, Lug and Wafer Types
API 609 — Butterfly Valves — Double Flanged, Lug and Wafer Types
The butterfly valve standard, and the source of the Category A / Category B distinction that decides which butterfly valve a piping class will accept.
API 609 covers butterfly valves in NPS 2 to NPS 60 in three executions: double flanged, lug and wafer. Category A covers concentric, resilient-seated valves — the economical isolation valve for water and low-pressure utility service. Category B covers eccentric and double-eccentric (and triple offset) valves rated by ASME Class, which is what refinery, offshore and power piping classes expect.
The 9th edition removed Category C, leaving Category A and B as the only defined groups. That matters when you are reverse-engineering an existing installation: a legacy valve marked Category C has to be re-specified against Category B or A.
Our licence 609-0298 covers butterfly valves — Category B, together with API Spec Q1. Metal-seated double eccentric and triple offset valves, fire-safe tested to API 607 where required, in WCB, CF8M, ductile iron, duplex and WC6 bodies.
Coverage
- NPS 2 – NPS 60 (DN50 – DN1500)
- Category A: concentric, resilient seated, wafer and lug
- Category B: eccentric, ASME Class rated, wafer/lug/double flanged
- ASME Class 150, 300, 600 (Category B)
- Soft seats (EPDM, NBR, PTFE) and metal seats
- Monogrammed under licence 609-0298 with API Spec Q1
Related standards
Send the piping class, not the part number
We check the dimensions, the material and the standard before we price — which is the part that decides whether the valve actually fits. RFQ answered within one working day.