The Stainless Steel Lap Joint Stub End (also called a lap joint flange stub end or Van Stone fitting) is used with a loose backing flange to create a flanged connection. The stub end is butt welded to the pipe, while the backing flange slides over the pipe and is free to rotate. This design has several advantages: the backing flange can rotate to align bolt holes without rotating the pipe; the flange can be made of a different material (e.g., carbon steel flange with stainless steel stub end) to save cost; and the flange can be removed for maintenance without cutting the pipe. The stub end has a formed lip that fits into the backing flange’s counterbore. The fitting is manufactured from ASTM A403 stainless steel (WP304L or WP316L). The sealing surface is machined to a smooth finish (Ra 3.2μm typical) to mate with a standard gasket.
Why Choose Us / Advantage
Cost Savings: Use carbon steel backing flange with stainless stub end — lower cost than all-stainless flange.
Bolt Hole Alignment: Rotating flange makes installation easy — no pipe twisting.
Easy Maintenance: Remove backing flange without cutting pipe.
Sanitary Surface: Smooth, crevice-free lip design eliminates bacteria traps.
Standard Dimensions: ASME B16.9 stub end with B16.5 flange dimensions.
Technical Data
★ Specification SS304L SS316L
★ Material (Stub End) ASTM A403 WP304L ASTM A403 WP316L
★ Material (Backing Flange) Customer choice (CS, SS, etc.) Customer choice
★ Type Lap Joint Stub End Lap Joint Stub End
★ Connection (to pipe) Butt weld (beveled end) Butt weld
★ Connection (to flange) Loose (flange slides on) Loose
★ Pressure Class 150 / Class 300 Class 150 / Class 300
★ Size Range 1/2″ – 24″ 1/2″ – 24″
★ Standard ASME B16.9 (stub); B16.5 (flange dims) ASME B16.9
★ Face Finish Smooth (Ra 3.2μm max) Smooth
Applications
● Pharmaceutical water systems requiring frequent disassembly for cleaning
● Chemical process lines where flange bolt alignment is difficult
● Food processing lines with regular gasket replacement
● Corrosive service with carbon steel backing flange (cost savings)
● Systems requiring future modification or expansion
