EN 1092-1 Type 11 PN 100 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 100. 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 100 is the high-pressure class of the EN series, rated for roughly 100 bar at room temperature, and the Type 11 series covers sizes DN 10 to DN 350.

PN stands for “Pression Nominale” — the nominal pressure class. A PN 100 flange is rated for a maximum working pressure of about 100 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 100 is specified where pressures move beyond the everyday PN 16–40 range: boiler feedwater and main steam lines, hydraulic and pressure-test circuits, gas compression and injection systems, chemical injection skids, refinery high-pressure units and offshore process systems. The joints see high bolt loads and often temperature cycling, which is exactly the duty the weld neck construction is designed for.

In duty they are close: Class 600 allows roughly 102 bar for A105 at ambient temperature, and PN 100 roughly 100 bar, so specifiers often 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. An EN PN 100 flange will not bolt to an ASME Class 600 flange of the same nominal size.

The Type 11 weld neck series in PN 100 runs from DN 10 to DN 350. The chart on this page also lists DN 400 and DN 500 rows, but those apply to the plate (01) and integral (21) types only — their Type 11 columns show a dash, and their weight cells are marked accordingly. Larger high-pressure weld necks are quoted case-by-case as special forgings.

At 100 bar the loose plate and collar constructions (Types 02, 04, 32–37) are no longer provided by the standard — the bolt loads and bending stresses are too high for them. At PN 100 the standard provides only the plate (01), blind (05), weld neck (11), hubbed slip-on (12) and integral (21) constructions — and the chart on this page is edited down further to the Type 11 weld neck columns alone: D, K and L mating dimensions with bolting, plus A, C2, H2, H3, N1, R and S.

From the weight columns in our chart: a DN 50 Type 11 flange weighs about 6.3 kg (14 lbs), a DN 100 about 14 kg (30 lbs), a DN 200 about 52 kg (115 lbs) and a DN 350 about 175 kg (387 lbs). These are approximate carbon-steel weights calculated from the standard dimensions — a PN 100 flange weighs roughly three times its PN 16 counterpart of the same size.

Form B1, the standard raised face with a serrated finish, is the default; Form B2 provides a smooth finish for special gaskets. At PN 100 the tongue/groove and spigot/recess forms (C–F) are also used where positive gasket location is wanted. Flat face (Form A) is generally not used at this class. State the facing form required — and the gasket type 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. High-pressure pipe walls vary widely, so 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.

The chart's bolting columns give the exact count and metric thread per DN: a DN 25 takes 4 × M16, a DN 50 takes 4 × M24, a DN 100 takes 8 × M27, a DN 200 takes 12 × M33 and a DN 350 takes 16 × M45. High-strength stud bolts are used at this class, and controlled-torque or tensioned bolting is common on critical joints. Bolt holes (column L) and the bolt circle (column K) are tabulated alongside.

At PN 100 bolt loads, soft sheet gaskets are generally unsuitable — the norm is a spiral wound gasket to EN 1514-2 or a kammprofile (grooved metal-faced) gasket to EN 1514-6, selected for the medium and temperature. Where tongue/groove or spigot/recess facings are specified, the gasket is located positively in the recess. Always match the gasket to the facing form and PN class of both flanges.

At 100 bar the question largely answers itself: the weld neck's tapered hub and full-penetration butt weld give the joint the strength and fatigue life of the pipe itself, and the weld can be volumetrically examined by radiography or UT. Hubbed slip-on (Type 12) flanges remain in the standard but are limited to less demanding positions; for pressure-bearing process lines, temperature cycling and cyclic loads, Type 11 is the specified construction.

When the line's design pressure (at design temperature, for your material group) exceeds the PN 100 rating of roughly 100 bar — remembering that the allowable pressure derates significantly at elevated temperature, so a 90-bar line at 300 °C may already need PN 160. Surge, water hammer and test pressures should be included in the check. See our PN 160, PN 250, PN 320 and PN 400 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 — routinely specified at this pressure class.

Yes. Besides standard EN 1092-1 dimensions we machine special bores, extended hubs and long weld neck versions, tongue/groove and recess facings, and flanges to customer drawings — including sizes above DN 350 as special high-pressure forgings, quoted case-by-case. Send the drawing or datasheet and we will quote to it.

Power generation (feedwater and main steam), refining and petrochemicals, gas processing and compression, hydrogen and industrial-gas plants, hydraulic and test-rig builders, and offshore process systems — any European-specification project whose pressures sit around the 100 bar mark. EPC contractors ordering to EN piping classes specify PN 100 Type 11 flanges on the high-pressure units of the plant.

Size (DN) and quantity, standard and type (EN 1092-1 Type 11), PN class, facing form (B1, B2, C–F), 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.