EN 1092-1 Type 11 PN 320 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 320. 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 320 is rated for roughly 320 bar at room temperature, and the chart on this page covers DN 10 to DN 250.

PN stands for “Pression Nominale” — the nominal pressure class. A PN 320 flange is rated for a maximum working pressure of about 320 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 320 is specified on ultra-high-pressure duty beyond PN 250: ammonia, methanol and urea synthesis loops, gas and hydrogen injection, supercritical circuits and heavy hydraulic or test systems. Joints at this class are torque-controlled or tensioned as a matter of course, with volumetrically examined butt welds.

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.

PN 320 sits between ASME Class 1500 (roughly 255 bar cold for A105) and Class 2500 (roughly 425 bar) in duty. The systems are dimensionally unrelated: EN 1092-1 uses DN sizes, metric bolting and its own facings, ASME B16.5 uses NPS sizes and imperial bolting — the two never bolt together at the same nominal size.

The PN 320 Type 11 series runs from DN 10 to DN 250. Bores stay small at these pressures — the joint force on even a DN 250 flange at 320 bar is enormous — and larger special forgings are quoted case-by-case.

From the weight columns in our chart: A DN 50 about 11 kg (25 lbs), a DN 100 about 44 kg (98 lbs), a DN 150 about 96 kg (211 lbs), a DN 200 about 179 kg (395 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 8 × M24, a DN 125 takes 12 × M33 and a DN 250 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 320 rating of roughly 320 bar — with careful attention to temperature derating. PN 400 is the top of the EN 1092-1 series; beyond it, special flange designs to EN 13445 or customer specifications take over. See the PN 400 Type 11 chart 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.

High-pressure chemical synthesis (ammonia, methanol, urea), gas and hydrogen plants, supercritical power circuits, and hydraulic or test-rig builders — any European-specification project around the 320 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.