Standards · JIS B 2220

JIS pipe flanges to JIS B 2220: pressure classes 5K to 63K – and what Zickwolff supplies

Shipbuilding, Japanese machinery and plant, the spare part for a line with a Japanese pedigree: there you find pipe flanges to JIS B 2220 instead of EN 1092-1 – with their own pressure classes, bolt patterns and nominal sizes. What the standard covers, why none of it fits PN or Class, and which JIS pipe flanges we supply.

Issued by: Japanese Industrial Standards (JIS), Japanese Standards Association
Standard: JIS B 2220 – Steel pipe flanges, 2012 edition
Pressure classes: 5K, 10K (also thin type), 16K, 20K, 30K, 40K, 63K
Nominal sizes: 10A to 1500A (A size, number = DN)
Facings: RF (raised face) and FF (flat face) – the standard knows more
Material: SS400 to JIS G 3101 – market equivalent S235JR, no standard equivalence
European counterpart: EN 1092-1 (PN) – in function, not in dimensions
At Zickwolff: we supply to order – no stock, lead time on request

What JIS B 2220 covers

JIS B 2220 is the Japanese dimensional standard for steel flanges on steel and stainless steel piping: weld neck (WN), slip-on (SO), plate, threaded and blind flanges in the nominal pressure classes 5K, 10K, 16K, 20K, 30K, 40K and 63K for nominal sizes 10A to 1500A. It fixes outside diameter, bolt circle, number and diameter of bolt holes, thickness and facing per class and size – as EN 1092-1 does for the PN world and ASME B16.5 for the Class world.

K, A, RF: the three abbreviations

K is the nominal pressure class. Historically the number stood for a nominal pressure in kgf/cm²; today it is a class designation like PN or Class – and as there, the allowable working pressure depends on material and temperature, not on the number. There is no conversion “10K = PN 10”. A is the nominal size: 50A corresponds to the number DN 50 – a nominal value, not a diameter. RF (raised face) and FF (flat face) are the facings; the standard knows further forms, in trade RF and FF are the rule.

Material

The usual grade is SS400 to JIS G 3101, an unalloyed structural steel. In trade it is equated with S235JR – that is market practice, not standard equivalence: chemical composition and testing are specified differently in JIS G 3101 and EN 10025-2. If you need a certificate to EN 10204, say so in the enquiry; what the certificate attests is explained on certificates to EN 10204.

Not interchangeable: JIS versus EN 1092-1 and ASME B16.5

A JIS pipe flange does not fit an EN or ASME flange of the same nominal size – outside diameter, bolt circle and number of bolts are defined independently in each world of standards. A 10K flange 100A matches neither the bolt pattern of PN 16 DN 100 nor that of Class 150 NPS 4; even where single dimensions happen to be similar, bolting them together without approval remains an improvisation.

The practical rule: compare the bolt pattern, not the number. Measure bolt circle, number and diameter of holes – how, see how to measure – and check against EN and ASME with the flange identifier. If no pattern matches, it is most likely JIS (or a works standard).

Three worlds, three numbers 10K, PN 16 and Class 150 denote three different pressure classes in three different systems. None of them is a working pressure in bar, and none converts into another – DN is not NPS, PN is not Class, and K is neither.

What the three numbers refer to: K (JIS B 2220) is the nominal pressure in the old unit kgf/cm² – 10K means 10 kgf/cm², about 0.98 MPa; what is permissible at which temperature is given in the standard per material. PN (EN 1092-1) is a designation number that corresponds only roughly to the allowable pressure in bar, at room temperature and for the weakest material group; the pressure-temperature table per material governs. Class (ASME B16.5) is a pressure-temperature class whose number historically derives from steam pressure in psi – Class 150 carries about 19.6 bar (285 psi) for carbon steel at 38 °C, not 150 of anything.

Which JIS pipe flanges are available from Zickwolff

The table shows what is set up in our item master: type, pressure class, facing and the range of nominal sizes. We supply JIS pipe flanges to order – no stock; how quickly something is available we clarify on request. Other types, classes or sizes of the standard: please enquire.

JIS pipe flanges to JIS B 2220 in the Zickwolff item master (type, pressure class, nominal sizes, availability)
Type	Pressure class	Facing	Nominal sizes	Availability
weld neck flange	5K	RF	10A to 500A (22 sizes)	to order
weld neck flange	10K	RF	10A to 500A (22 sizes)	to order
weld neck flange	16K	RF	10A to 600A (22 sizes)	to order
weld neck flange	20K	RF	10A to 150A (13 sizes)	to order
weld neck flange	30K	RF	15A to 400A (17 sizes)	to order
weld neck flange	40K	RF	15A to 400A (17 sizes)	to order
weld neck flange	63K	RF	15A to 400A (17 sizes)	to order
blind flange	5K	FF	10A to 200A (15 sizes)	to order
blind flange	10K	FF	10A to 100A (11 sizes)	to order
plate flange (slip-on)	5K	FF	on request	available on request
threaded flange	5K	FF	on request	available on request

Dimensions of JIS pipe flanges we state only on request and per order – unlike EN 1092-1 and ASME B16.5 there is no dimension table here yet. If you need dimensions for comparison, send us pressure class, nominal size and type.

Frequently asked questions about JIS pipe flanges

Is JIS 10K the same as PN 10 or PN 16?

No. 10K is a nominal pressure class of the JIS world with its own bolt pattern; PN 10 and PN 16 are classes to EN 1092-1 with other outside diameters, bolt circles and bolt numbers. The numbers cannot be converted, and the flanges do not fit each other.

Does a JIS pipe flange fit an EN or ASME flange?

As a rule, no – bolt circle, number of bolts and outside diameter differ. Connecting a JIS line to an EN line needs a transition (flange pair with spool or a special flange to drawing); we check that case by case.

Is JIS 10K equal to Class 150?

No. Both are pressure classes, but from different systems with different bolt patterns and material groups. That both count as “the low class” in trade does not make them interchangeable.

What does 50A mean on a JIS pipe flange?

The A nominal size – it corresponds to the number DN 50 and is a nominal value, not a measured diameter. The matching pipe has the same nominal value to a JIS pipe standard; only the pipe standard states the outside diameter.

Which JIS pipe flanges does Zickwolff supply?

Weld neck flanges 5K to 63K, blind flanges 5K and 10K in SS400 (market equivalent S235JR) to order; plate and threaded flanges as well as other classes and sizes on request. The table above gives the ranges set up – dimensions and lead times per enquiry.

JIS pipe flanges – to order from one source

Tell us type, pressure class, nominal size, facing, material, certificate and quantity – we check availability and lead time and tell you whether an EN or ASME part would be the alternative.

Send an inquiry

Your inquiry to Zickwolff

Send us what you have – designation, standard, quantity, date. We will clarify the rest with you.

One item or a question

Send inquiry

Not in stock? We procure it – single items too.

Designation, standard and quantity are enough.

Several items

Send bill of materials

200 items? One parts list is enough – we deliver complete.

Attach it as a file.

Helpful if already known: project and country, date needed, certificates, packaging and language of the packing lists. If anything is missing, we will ask.

It is urgent

Request express

When do you need it? Express delivery, to the site if required.

Tell us by when you need the material – we will tell you what is possible.

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Basis: the publicly accessible scope of JIS B 2220:2012 and our own product data (item master as of 06.10.2026); no dimensions from the standard. Information without guarantee – the standard and the order are decisive.