SS 904L Long Weld Neck FlangeASTM A182 · ASME B16.5 (flange end) · Manufacturer, stockist & exporter, India
Alloy 904L · UNS N08904 · LWN
An SS 904L long weld neck flange is a weld neck flange with an extended straight neck, used as a vessel nozzle, made from SS 904L to ASTM A182 F904L. 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 904L Long Weld Neck Flange?
- What it is
- A weld neck flange with an extended straight neck, used as a vessel nozzle
- Material
- ASTM A182 F904L
- Dimensions
- ASME B16.5 (flange end)
- Grade
- SS 904L · UNS N08904
- Best at
- Dilute sulphuric acid, phosphoric acid and chloride-bearing cooling water
SS 904L Long Weld Neck Flange Specification
| Product | SS 904L Long Weld Neck Flange |
|---|---|
| Material standard | ASTM A182 F904L |
| 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 · dimensional · NDT and IGC on request |
| Documents | EN 10204 3.1 · 3.2 with third-party inspection |
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 904L Long Weld Neck Flange: Why 904L 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 904L, 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 904L is picked for dilute sulphuric acid, phosphoric acid and chloride-bearing cooling water. |
|---|---|
| Typical service | Sulphuric acid plants — Coolers, piping and tanks for dilute sulphuric acid. |
| Bolting | as the project specifies |
| Welding to carbon steel | ER309L (or E309L electrode) is the usual filler when joining it to carbon steel |
| Matching filler | ER385 (AWS A5.9) |
SS 904L Long Weld Neck Flange Chemical Composition
| Element | Weight % |
|---|---|
| Nickel | 23.0 – 28.0 |
| Chromium | 19.0 – 23.0 |
| Molybdenum | 4.0 – 5.0 |
| Copper | 1.0 – 2.0 |
| Carbon | 0.020 max |
| Manganese | 2.00 max |
| Silicon | 1.00 max |
| Nitrogen | 0.10 max |
SS 904L Long Weld Neck Flange Mechanical Properties
| Annealed plate & sheet | Value |
|---|---|
| Tensile strength | 490 MPa · 71 ksi |
| Yield strength 0.2% | 220 MPa · 31 ksi |
| Elongation | 35% |
| Hardness | 90 HRB max |
Full chemistry, properties and equivalents are on the SS 904L grade page.
Other SS 904L flanges
SS 904L Long Weld Neck Flanges for export
FOB / CIF · Nhava Sheva (JNPT), MumbaiSS 904L 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 904L 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.
Can SS 904L 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 904L long weld neck flanges?
The material is ASTM A182 F904L; 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 904L 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 mill certificates as standard, 3.2 with third-party inspection on request, plus dimensional and PMI reports.
Sources: the ASTM / ASME specifications named on this page and producer datasheets · Last updated October 2026