EN 1092-1 Type 11 PN 250 Weld Neck Flange — Dimensions, Weights & Bolting

It is a weld neck flange made to the European standard EN 1092-1 in nominal pressure class PN 250. In EN 1092-1, “Type 11” is the designation for the weld neck (welding neck) flange — a flange with a long tapered hub that is butt-welded to the pipe. PN 250 is rated for roughly 250 bar at room temperature, and the chart on this page covers DN 10 to DN 300.

PN stands for “Pression Nominale” — the nominal pressure class. A PN 250 flange is rated for a maximum working pressure of about 250 bar at room temperature, with the exact allowable pressure depending on the material group and falling as temperature rises, per the pressure-temperature tables in EN 1092-1. The PN series runs 2.5, 6, 10, 16, 25, 40, 63, 100, 160, 250, 320 and 400.

PN 250 is specified on ultra-high-pressure duty: supercritical steam circuits, gas and hydrogen compression and injection, ammonia and methanol synthesis loops, hydraulic and pressure-test systems. Joints at this class are routinely torque-controlled or tensioned, and the weld neck's butt-weld integrity is non-negotiable.

From PN 160 upward EN 1092-1 provides only two constructions: the weld neck (Type 11) and the integral flange (Type 21) — plate, loose, blind and slip-on types are not rated for these pressures. The chart on this page is edited down further to the Type 11 columns alone: the D, K and L mating dimensions with bolting, plus neck OD A, thickness C2, lengths H2 and H3, neck diameter N1, radius R and neck wall S.

In duty they are close: Class 1500 allows roughly 255 bar for A105 at ambient temperature and PN 250 roughly 250 bar, so specifiers treat them as counterparts. But the flanges are not interchangeable — EN 1092-1 uses DN sizes, metric bolting and its own bolt circles and facings, while ASME B16.5 uses NPS sizes and imperial bolting.

The Type 11 weld neck series in PN 250 runs from DN 15 to DN 250. The chart also lists DN 10 and DN 300 rows, but their weld-neck-specific columns are blank in the standard — those sizes, and anything larger, are quoted case-by-case as special forgings against the design conditions.

From the weight columns in our chart: A DN 50 about 9.1 kg (20 lbs), a DN 100 about 29 kg (63 lbs), a DN 150 about 62 kg (137 lbs), a DN 200 about 114 kg (252 lbs). These are approximate carbon-steel weights calculated from the standard dimensions with a standard bore — actual weight varies with the bore and material.

Form B1 raised face (standard) and Form B2 smooth; tongue/groove and spigot/recess (Forms C–F) are common at this class for positive gasket location. State the form required — and the gasket it must suit — on your enquiry.

The bore is machined to match the inside diameter of the mating pipe so the joint has a smooth, unrestricted flow path and a clean butt weld. State the pipe wall thickness or internal diameter (or the pipe standard and series) with your order — the chart's S column gives the preferred neck wall thickness for each size.

We manufacture them in carbon steel A105/P250GH and low-temperature A350 LF2, stainless steel 304/L (1.4301/1.4307), 316/L (1.4401/1.4404), 321 (1.4541), 310, 347 and 410, 254 SMO (1.4547), 904L (1.4539), duplex 2205 (1.4462), super duplex 2507 (1.4410), alloy steel F1–F91, Monel 400/K500, Inconel 600/625/825, Hastelloy C276/C22, titanium Gr. 2/5, copper nickel 90/10 and 70/30, and bimetal/clad — all with EN 10204 3.1 certificates.

It rises with size — the chart's bolting columns give the exact count and metric thread per DN: a DN 10 takes 4 × M16, a DN 50 takes 4 × M24, a DN 125 takes 8 × M30 and a DN 300 takes 16 × M48. Bolt holes (column L) and the bolt circle (column K) are also tabulated, so gasket and fastener take-offs can be made straight from this page.

spiral wound (EN 1514-2) or kammprofile (EN 1514-6) gaskets — soft sheet gaskets are unsuitable at this bolt load. Always match the gasket to the facing form and PN class of both flanges.

The tapered hub and full-penetration butt weld make the joint as strong and fatigue-resistant as the pipe itself, the weld is easy to examine by radiography or UT, and the matched bore eliminates turbulence and crevice corrosion at the joint. Cheaper constructions have their place in undemanding services, but Type 11 is the engineering choice for process lines, temperature cycling and critical media.

When the line's design pressure (at design temperature, for your material group) exceeds the PN 250 rating of roughly 250 bar — with careful attention to temperature derating at steam and synthesis conditions. Surge and test pressures should be included in the check. See the PN 320 and PN 400 Type 11 charts linked on this page.

Every batch is dimensionally inspected against EN 1092-1, marked with size, PN class, material grade and heat number, and supplied with EN 10204 3.1 mill test certificates. PMI verification, ultrasonic and magnetic-particle examination, impact testing for low-temperature grades, NACE MR0175 compliance and third-party witness inspection by LR, BV, DNV, SGS, TÜV or IBR are available on request.

Yes. Besides standard EN 1092-1 dimensions we machine special bores, extended hubs and long weld neck versions, special facings and drilling, and flanges to customer drawings — including sizes outside the standard series as special forgings, quoted case-by-case. Send the drawing or datasheet and we will quote to it.

Supercritical and ultra-supercritical power plants, gas processing and injection, hydrogen and syngas plants, high-pressure chemical synthesis (ammonia, methanol, urea), and hydraulic or test-rig builders — any European-specification project around the 250 bar mark.

Size (DN) and quantity, standard and type (EN 1092-1 Type 11), PN class, facing form, pipe wall thickness or bore, material grade, any impact-test or NACE requirement, and the certification and inspection you need. Tesco Steel & Engineering is an ISO 9001:2015 certified flange manufacturer and exporter in Mumbai, India, shipping worldwide with sea-worthy packing.