Flange Size Checker – ASME 150/300 & PN16

Check a flange size or identify an unknown flange

Pick a standard and size to see its outside diameter, bolt circle (PCD) and bolt holes, or enter what you measured and the tool will tell you which flange you have. Covers ASME B16.5 Class 150 & 300 and EN 1092-1 / DIN PN10 & PN16.

Standard

Nominal size

How to measure a flange

Outside diameter (OD)Measure straight across the flange, edge to edge, through the centre.
Bolt circle (PCD)Measure from the centre of one bolt hole to the centre of the hole directly opposite. Centres are hard to find by eye, so measure from the near edge of one hole to the far edge of the opposite hole instead. It gives the same number.
Bolt holesCount the holes. It is often the quickest way to separate two standards that have similar OD and PCD.
Enter and checkPut the numbers into Identify a flange above. If two standards come out close, the hole count settles it.

Standards in this tool

American

ASME B16.5 Class 150

Also called ANSI or ASA 150. The most common low-pressure flange in water, fire-fighting and general process lines. Sizes ½″ to 24″.

American

ASME B16.5 Class 300

Heavier drilling with a larger OD and PCD than Class 150 at the same size, used on higher-pressure steam, oil and process piping. Sizes ½″ to 24″.

European / German

EN 1092-1 / DIN PN10 & PN16

Metric drilling used on pumps, valves and European-spec equipment. PN10 and PN16 share dimensions up to DN150 and differ from DN200 up. DN15 to DN600.

Flange size questions

How do I find out which flange I have?

Measure the outside diameter and the bolt circle (PCD), count the bolt holes, and enter them in the Identify tab. The tool compares your numbers with every flange in its tables and lists the closest standard and size first.

What is the difference between OD and PCD?

OD is the full outside diameter of the flange. PCD (pitch circle diameter, or bolt circle) is the diameter of the circle running through the centres of the bolt holes. Two flanges can have nearly the same OD but a different PCD, so you need both to identify a flange.

Why does the tool show more than one match?

Some standards are very close at certain sizes. For example, a 2″ Class 150 flange and a DN50 PN16 flange are only a few millimetres apart. When your measurement fits more than one, all of them are listed, closest first. Pick the bolt-hole count to narrow it down.

Will a Class 150 flange bolt up to a PN16 flange?

Usually not. Even where the sizes look similar, the PCD, hole size and hole count are different, so the bolts will not line up properly. Always match the mating flange, valve or pump to the same standard and class.

Why is flange thickness not shown?

Thickness depends on the flange type (slip-on, weld neck, blind, plate), the material and the edition of the standard, so it is not a reliable way to identify a flange. OD, PCD and hole count are fixed by the standard. Ask us for the thickness of a specific flange you want to order.

I need BS 10 (Table D / E) or IS 6392 flanges. Can you help?

Yes. Send us your measurements or drawing on WhatsApp and our team will confirm the standard and quote for it.

Need flanges supplied?

Nirmankar by Deetya Enterprise supplies MS and SS flanges in ASA 150, IS and hub / weld-neck types. Send us the size from the tool and we will reply with rates and availability.

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Dimensions are nominal values from ASME B16.5 and EN 1092-1, rounded to 0.1 mm. Always confirm against the approved drawing or the manufacturer’s test certificate before ordering.

9151566755

Flange Size Checker & Identification Tool