SS 304L Threaded FlangeASTM A182 · ASME B16.5 · Manufacturer, trader & exporter, India
AISI 304L · UNS S30403 · THD
An SS 304L threaded flange is a flange with a tapered internal thread that screws onto threaded pipe, made from SS 304L to ASTM A182 F304L. Use a threaded flange where welding is not allowed — for example in explosive areas — on small-bore, low-pressure lines. Threads are NPT to ASME B1.20.1.
- ASTM A182
- ASME B16.5
- EN 10204 3.1 / 3.2
- Export packing
Reviewed by the Kanak Steel & Engineering Co. technical team · Updated October 2026
What is an SS 304L Threaded Flange?
- What it is
- A flange with a tapered internal thread that screws onto threaded pipe
- Material
- ASTM A182 F304L
- Dimensions
- ASME B16.5 · ASME B1.20.1
- Grade
- SS 304L · UNS S30403
- Best at
- Welded tanks, piping and vessels in general corrosive service
SS 304L Threaded Flange Specification
| Product | SS 304L Threaded Flange |
|---|---|
| Material standard | ASTM A182 F304L |
| Dimensional standard | ASME B16.5 · ASME B1.20.1 |
| 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 Threaded Flange
Use a threaded flange where welding is not allowed — for example in explosive areas — on small-bore, low-pressure lines. Threads are NPT to ASME B1.20.1.
- NPT threads to ASME B1.20.1
- Not for cyclic or high-temperature service
- Seal-welding is sometimes added after make-up
More on choosing: Threaded flange guide.
SS 304L Threaded Flange: Why 304L for threaded flanges
Use a threaded flange where welding is not allowed — for example in explosive areas — on small-bore, low-pressure lines. Threads are NPT to ASME B1.20.1. In SS 304L, 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 304L is picked for welded tanks, piping and vessels in general corrosive service. |
|---|---|
| Typical service | Process piping — Welded lines in chemical and pharma plants. |
| B16.5 material group | 2.3 |
| 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 | ER308L (AWS A5.9) |
SS 304L Threaded 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 S30403.
SS 304L Threaded 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 S30403 — Annealed plate & sheet.
Full chemistry, properties and equivalents are on the SS 304L grade page.
Other SS 304L flanges
SS 304L Threaded 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 304L Threaded Flange — questions buyers ask
Can threaded flanges be used in high-pressure service?
They are rated like other flanges in their class, but threaded joints are not recommended for cyclic, high-temperature or highly corrosive service.
What pressure rating does a SS 304L threaded flange have?
It depends on class and temperature. SS 304L forgings are in ASME B16.5 material group 2.3; read your class column in that group's table at the design temperature.
Can SS 304L threaded 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 304L threaded flanges?
The material is ASTM A182 F304L; dimensions follow ASME B16.5 · ASME B1.20.1. Always state both on your purchase order, with the edition if your project specifies one.
What decides the price of a SS 304L threaded 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