Valve Face-to-Face Dimensions

Drop-in Replacement Rule

A valve is a drop-in replacement only if it matches the original valve's face-to-face dimension (within +0/−0 mm for butt-weld ends; within flange gasket surface tolerance for flanged ends). Any deviation requires a spool piece. Always verify with the manufacturer data sheet, not catalogue tables.

Short vs. Long Pattern (Gate Valves)

ASME B16.10 defines short pattern (Table 1) and long pattern (Table 2) for gate valves. Long pattern valves are 50–100 mm longer per size. Long pattern is specified where stem travel must accommodate thick-walled pipe or pipe insulation. Most standard API 600 gate valves are short pattern.

API 6D vs. ASME B16.10

API 6D pipeline valves may have different face-to-face dimensions from ASME B16.10. For trunnion-mounted ball valves above NPS 6, always cross-check the manufacturer's API 6D data sheet. Pipeline operators often specify minimum face-to-face dimensions in their project specifications.

Butt-Weld End Valves

Butt-weld end (BW) valves have end-to-end dimensions per ASME B16.10 Table 14/15. The end-to-end is slightly longer than the face-to-face flanged equivalent because the BW pipe stub is included. Always confirm: BW end preparation (bevelled per ASME B16.25) and wall thickness match are the spool fabricator's responsibility.