ASME B16.10

Covers — face-to-face and end-to-end dimensions of straightway valves, and center-to-face / center-to-end dimensions of angle valves, by size, rating class, and end type, so valves of a given type are interchangeable.

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

• Pressure-temperature ratings and wall thickness → ASME B16.34.
• Product design and trim → the applicable API/MSS valve standard.
• Flange dimensions/drilling → ASME B16.5 / B16.47.

The standard exists to guarantee installation interchangeability; it does not qualify the valve for service on its own.

B16.10 sets minimum requirements for valve laying lengths:

• Dimensions — tabulated face-to-face / end-to-end lengths by valve type, size, class, and end connection.
• Tolerances — allowable dimensional tolerances so replacements fit existing spool gaps.
• Applicability — covers common valve types (gate, globe, check, ball, plug, butterfly) referenced by the product valve standards.

ASME B16.10 standardizes the laying lengths of valves so that any conforming valve of a given type, size, class, and end connection can replace another without re-piping. Straightway valves use face-to-face (flanged) or end-to-end (welding) dimensions; angle valves use center-to-face dimensions.

Because it is dimensional only, the standard is always used alongside B16.34 (rating and wall thickness) and the product valve standard (design and trim). Specifying laying length early lets the piping designer fix spool lengths before valves are procured.

Engineering Note: Confirm both the valve type and end connection when reading B16.10 — a flanged and a butt-weld version of the same valve have different laying lengths.