JIS B2220 10K Flange Dimensions — DN15 to DN300 (Bolt Circles, Bolting, Thickness)

Dimension table for JIS B2220 10K slip-on/plate flanges from 15A to 300A: outside diameter, bolt-circle diameter, number and size of bolts, flange thickness, with guidance on mating JIS to EN/PN and ASME class flanges.

JIS 10K dimension table

Values for the common JIS B2220 10K slip-on and plate flange pattern with raised face; hub and weld-neck variants share OD, PCD and bolting. Japanese drawings quote nominal bore with the suffix A (50A = DN50 = 2").

JIS against PN and ASME

JIS 10K, EN 1092-1 PN10/PN16 and ASME class 150 flanges do not interchange: at DN50, JIS 10K drills 4 × M16 on a 120 mm circle, PN16 drills 4 × 18 mm holes on 125 mm (PN16 chart), and class 150 drills 4 × 3/4" holes on 120.6 mm — close enough to tempt, far enough to leak or crack. The only safe mixed joint is a purpose-made adapter spool. Japanese-built vessels carry JIS piping throughout, so spares for them (gaskets, bolting, M16 bolts, counter-flanges) must be ordered to JIS tables; European yards follow EN 1092-1 (PN10/PN25) and US-spec plants ASME B16.5 (B16.47 large diameters).

Higher JIS ratings

The same B2220 system defines 5K (lighter, often found on non-critical shipboard lines), 16K and 20K patterns with their own PCDs and bolting — a 10K gasket or counter-flange does not fit a 16K line of the same bore. The rating is cast or stamped on the flange rim together with the nominal size; when it is unreadable, identify by measuring OD, PCD and bolt count against the tables before ordering mating parts.

Frequently asked questions

What are the dimensions of a JIS 10K 50A flange?

A JIS B2220 10K 50A (DN50) flange is 155 mm outside diameter with four M16 bolts on a 120 mm bolt circle, 16 mm thick.

Are JIS 10K and PN16 flanges interchangeable?

No — at most sizes the bolt-circle diameters and hole counts differ (DN50: 120 mm/4 holes vs 125 mm/4 holes), so they neither bolt up correctly nor seal reliably.

What does 50A mean on a Japanese drawing?

The nominal bore in millimetres with the JIS suffix A: 50A equals DN50 (2 inch nominal).

Does JIS 10K match ASME class 150?

No. Dimensions are close at some sizes but hole diameters, PCDs and facing differ; use a transition spool where the two systems meet.

Which JIS rating is on my flange?

JIS flanges are marked with size and rating (5K/10K/16K/20K) on the rim; if unreadable, measure OD, bolt-circle diameter and bolt count and match them to the B2220 tables.

Reference compiled for identification and cross-reference. Dimensions are nominal; confirm against the controlling Multiple 2026 edition revision and the specific component data sheets before manufacture or procurement. All trademarks are the property of their respective owners.