A similar pressure rating does not mean two flanges will bolt together. What decides it is the bolt circle and the bolt count. This chart puts the three standards side by side, with the figures taken from our own product pages — so you can check any row for yourself.
| Size | DN | OD D — JIS 10K | D1 — JIS 10K | Bolts — JIS 10K | OD D — ANSI 150 | D1 — ANSI 150 | Bolts — ANSI 150 | OD D — PN16 | D1 — PN16 | Bolts — PN16 |
|---|---|---|---|---|---|---|---|---|---|---|
| 1″ | 25 | 125 | 90 | 4-M16 | 108 | 79 | 4-Ø16 | 115 | 85 | 4-Ø14 |
| 1¼″ | 32 | 136 | 101 | 4-M16 | 116 | 89 | 4-Ø16 | 140 | 100 | 4-Ø18 |
| 1½″ | 40 | 140 | 105 | 4-M16 | 126 | 98.5 | 4-Ø16 | 150 | 110 | 4-Ø18 |
| 2″ | 50 | 155 | 120 | 4-M16 | 150 | 120.7 | 4-Ø19 | 165 | 125 | 4-Ø18 |
| 2½″ | 65 | 175 | 140 | 4-M16 | 180 | 139.7 | 4-Ø19 | 185 | 145 | 4-Ø18 |
| 3″ | 80 | 185 | 150 | 8-M16 | 190 | 152.4 | 4-Ø19 | 200 | 160 | 8-Ø18 |
| 4″ | 100 | 210 | 175 | 8-M16 | 229 | 190.5 | 8-Ø19 | 220 | 180 | 8-Ø18 |
All dimensions in mm. D = flange outside diameter, D1 = bolt circle. Source of each column, as printed: JIS 10K from the JIS 10K cast steel Y-strainer; ANSI 150 from the ANSI 150 SS316 gate valve; PN16 from the PN10/16 SS316 ball valve. The catalogue prints JIS bolts as a thread size (M16) and ANSI/PN bolts as a hole diameter (Ø) — two different measurements, so do not compare them directly.
| Pair | At which sizes | Notes |
|---|---|---|
| JIS 10K ↔ ANSI 150 | 2″ and 2½″ only | Bolt circles of 120 vs 120.7 mm and 140 vs 139.7 mm — effectively the same, with the same bolt count (4). Every other size differs, and at 3″ JIS takes 8 bolts where ANSI 150 takes 4. |
| JIS 10K ↔ PN16 | 1¼″ only — with a caveat | 101 vs 100 mm, both 4 bolts. One millimetre apart on paper; do not rely on it without measuring the flange in front of you. At other sizes they are 5–15 mm apart. |
| ANSI 150 ↔ PN16 | None in this range | The closest is 5.3 mm (2½″: 139.7 vs 145). At 3″ even the bolt counts differ, 4 vs 8. |
This chart sets three different product series from the same catalogue beside each other. Flange dimensions are set by the flange standard, not by the type of valve — but if you are ordering into an existing joint, measure the mating flange rather than trusting any chart.
Two flanges with similar pressure ratings can have bolt circles more than a centimetre apart. Check D1 first — if it does not match, nothing else matters.
A matching bolt circle does not help if the number of holes differs. At 3″, JIS 10K has 8 holes and ANSI 150 has 4 — only half of them line up.
The catalogue prints JIS bolts as a thread size (M16) and ANSI bolts as a hole diameter (Ø19). Make sure you are comparing like with like, and check flange thickness against your bolt length.
Send a photo of the existing flange plus one measurement — the outside diameter, or the distance between two opposite holes. We will match it against stock and reply within 2 working hours.
Across 1″–4″, only at 2″ and 2½″ do the bolt circles meet (120 vs 120.7 mm; 140 vs 139.7 mm), and even there both sides must have 4 bolts. At every other size they are 6.5–15.5 mm apart, and at 3″ the bolt counts differ (8 vs 4).
Because the pressure rating and the bolt pattern were set by different standards bodies with different histories. JIS 10K is roughly 1.0 MPa and ANSI 150 roughly 1.9 MPa at room temperature — close — but the bolt patterns were never harmonised. Similar pressure does not imply similar geometry.
No — each pressure class has its own bolt pattern. We also hold the ANSI 300 series; send us the class and size you need and we will reply with the dimensions as printed for that series.
Measure two things: the flange outside diameter and the distance between two opposite holes (that is the bolt circle), then count the holes. Send those three numbers on WhatsApp — that is enough to identify the standard.
Related: JIS square flanges · All flanges · Shipbuilding & marine · PDF catalogues.
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