SS 304 Long Weld Neck FlangeASTM A182 · ASME B16.5 (flange end) · Manufacturer, trader & exporter, India
AISI 304 · UNS S30400 · LWN
An SS 304 long weld neck flange is a weld neck flange with an extended straight neck, used as a vessel nozzle, made from SS 304 to ASTM A182 F304. Long weld neck flanges are used as nozzles on vessels and columns, with the neck welded into the shell. Standard neck lengths are 9" and 12", or made to drawing.
- ASTM A182
- ASME B16.5 (flange end)
- EN 10204 3.1 / 3.2
- Export packing
Reviewed by the Kanak Steel & Engineering Co. technical team · Updated October 2026
What is an SS 304 Long Weld Neck Flange?
- What it is
- A weld neck flange with an extended straight neck, used as a vessel nozzle
- Material
- ASTM A182 F304
- Dimensions
- ASME B16.5 (flange end)
- Grade
- SS 304 · UNS S30400
- Best at
- General corrosion resistance, food, water and architectural work
SS 304 Long Weld Neck Flange Specification
| Product | SS 304 Long Weld Neck Flange |
|---|---|
| Material standard | ASTM A182 F304 |
| Dimensional standard | ASME B16.5 (flange end) |
| Sizes | ½" – 24" (ASME B16.5) · 26" – 60" (ASME B16.47) |
| Pressure class | Class 150, 300, 400, 600, 900, 1500, 2500 · PN 6 – PN 100 |
| Facing | RF · FF · RTJ · tongue & groove |
| Bore | To match pipe schedule (state on order) |
| Testing | PMI (as specified in the PO) · dimensional · NDT and IGC on request |
| Documents | EN 10204 3.1 or 3.2 on request / as specified in the PO |
When to Choose a Long Weld Neck Flange
Long weld neck flanges are used as nozzles on vessels and columns, with the neck welded into the shell. Standard neck lengths are 9" and 12", or made to drawing.
- Heavy-barrel and equal-barrel designs
- Neck length 9" / 12" or to drawing
- Often machined from solid bar in alloys
More on choosing: Long weld neck flange guide.
SS 304 Long Weld Neck Flange: Why 304 for long weld neck flanges
Long weld neck flanges are used as nozzles on vessels and columns, with the neck welded into the shell. Standard neck lengths are 9" and 12", or made to drawing. In SS 304, the choice usually comes down to the medium and temperature — the rows here are the points buyers check for this exact combination.
| Why this grade | Stainless flanges are chosen where carbon steel would rust or contaminate the process. SS 304 is picked for general corrosion resistance, food, water and architectural work. |
|---|---|
| Typical service | Food & dairy — Tanks, piping and equipment that must be cleaned daily. |
| B16.5 material group | 2.1 |
| Bolting | ASTM A193 B8 studs with A194 8 nuts |
| Welding to carbon steel | ER309L (or E309L electrode) is the usual filler when joining it to carbon steel |
| Matching filler | ER308 / ER308L (AWS A5.9) |
SS 304 Long Weld Neck Flange Chemical Composition
Under technical review for TDS.
| Element | Current requirement |
|---|---|
| Chromium | As specified |
| Nickel | As specified |
| Carbon | As specified |
| Manganese | As specified |
| Silicon | As specified |
| Nitrogen | As specified |
| Phosphorus | As specified |
| Sulphur | As specified |
Numerical specification requirements are published only after the applicable current standard edition has been verified. Governing specification to be verified: ASTM A240 for UNS S30400.
SS 304 Long Weld Neck Flange Mechanical Properties
Under technical review for TDS.
| Property | Current requirement |
|---|---|
| Tensile strength | As specified |
| Yield strength 0.2% | As specified |
| Elongation | As specified |
| Hardness | As specified |
Numerical specification requirements are published only after the applicable current standard edition has been verified. Governing specification and condition to be verified: ASTM A240 for UNS S30400 — Annealed plate & sheet.
Full chemistry, properties and equivalents are on the SS 304 grade page.
Other SS 304 flanges
SS 304 Long Weld Neck Flange dimensions — ASME B16.5 Class 150 & 300
Outside diameter, thickness and bolting are set by size and class. Values in mm; thickness excludes the 1.6 mm raised face.
| NPS | Cl 150 OD | Cl 150 thickness | Cl 150 bolt circle | Cl 150 bolts | Cl 300 OD | Cl 300 thickness | Cl 300 bolt circle | Cl 300 bolts |
|---|---|---|---|---|---|---|---|---|
| ½" | 90 | 9.6 | 60.3 | 4 × ½" | 95 | 12.7 | 66.7 | 4 × ½" |
| 1" | 110 | 12.7 | 79.4 | 4 × ½" | 125 | 15.9 | 88.9 | 4 × ⅝" |
| 1½" | 125 | 15.9 | 98.4 | 4 × ½" | 155 | 19.1 | 114.3 | 4 × ¾" |
| 2" | 150 | 17.5 | 120.7 | 4 × ⅝" | 165 | 20.7 | 127.0 | 8 × ⅝" |
| 3" | 190 | 22.3 | 152.4 | 4 × ⅝" | 210 | 27.0 | 168.3 | 8 × ¾" |
| 4" | 230 | 22.3 | 190.5 | 8 × ⅝" | 255 | 30.2 | 200.0 | 8 × ¾" |
| 6" | 280 | 23.9 | 241.3 | 8 × ¾" | 320 | 35.0 | 269.9 | 12 × ¾" |
| 8" | 345 | 27.0 | 298.5 | 8 × ¾" | 380 | 39.7 | 330.2 | 12 × ⅞" |
| 10" | 405 | 28.6 | 362.0 | 12 × ⅞" | 445 | 46.1 | 387.4 | 16 × 1" |
| 12" | 485 | 30.2 | 431.8 | 12 × ⅞" | 520 | 49.3 | 450.8 | 16 × 1⅛" |
Full chart: ASME B16.5 flange dimensions.
SS 304 Long Weld Neck Flange — questions buyers ask
What is the difference between equal-barrel and heavy-barrel LWN?
Equal-barrel has a uniform neck; heavy-barrel has a thicker neck for extra reinforcement at the vessel wall.
What pressure rating does a SS 304 long weld neck flange have?
It depends on class and temperature. SS 304 forgings are in ASME B16.5 material group 2.1; read your class column in that group's table at the design temperature.
Can SS 304 long weld neck flanges be welded to carbon steel?
Yes — ER309L (or E309L electrode) is the usual filler when joining it to carbon steel.
Which standard covers SS 304 long weld neck flanges?
The material is ASTM A182 F304; dimensions follow ASME B16.5 (flange end). Always state both on your purchase order, with the edition if your project specifies one.
What decides the price of a SS 304 long weld neck flange?
The alloy price, the size and pressure class, quantity, and the testing and documents required. Send your list and we quote the same working day.
What documents do you supply?
EN 10204 3.1 or 3.2 certificates available on request / as specified in the PO; dimensional reports as required. PMI can be arranged depending on product and requirements, as specified in the PO.
Sources: the ASTM / ASME specifications named on this page and producer datasheets · Last updated October 2026