ASTM A333 Gr 6 Socket Weld FlangeASTM A350 · ASME B16.5 · Manufacturer, trader & exporter, India
SA-333 Gr 6 · Low-temperature carbon steel pipe · SWRF
An ASTM A333 Gr 6 socket weld flange is a flange with a counterbore socket into which the pipe is inserted and fillet-welded, for use with ASTM A333 Gr 6 pipe. ASTM A333 Gr 6 itself is a pipe or plate specification, so the matching socket weld flange is made to ASTM A350 LF2 — which is what we supply for A333 Gr 6 lines. Socket weld flanges suit small-bore, high-pressure lines, usually 2" and under. A 1.6 mm (1/16") expansion gap is left at the bottom of the socket before welding.
- ASTM A350
- 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 ASTM A333 Gr 6 Socket Weld Flange?
- What it is
- A flange with a counterbore socket into which the pipe is inserted and fillet-welded
- Material
- ASTM A350 LF2
- Dimensions
- ASME B16.5
- Grade
- ASTM A333 Gr 6
- Best at
- Cold-climate and refrigerated piping down to −45 °C
ASTM A333 Gr 6 Socket Weld Flange Specification
| Product | ASTM A333 Gr 6 Socket Weld Flange |
|---|---|
| Material standard | ASTM A350 LF2 |
| Dimensional standard | ASME B16.5 |
| 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 | Chemical & mechanical per heat · NDT · impact where specified |
| Documents | EN 10204 3.1 or 3.2 on request / as specified in the PO |
When to Choose a Socket Weld Flange
Socket weld flanges suit small-bore, high-pressure lines, usually 2" and under. A 1.6 mm (1/16") expansion gap is left at the bottom of the socket before welding.
- Leave a 1.6 mm gap before welding
- Not recommended where crevice corrosion is a concern
- Bore to match pipe schedule
More on choosing: Socket weld flange guide.
ASTM A333 Gr 6 Socket Weld Flange: Why A333 Gr 6 for socket weld flanges
Socket weld flanges suit small-bore, high-pressure lines, usually 2" and under. A 1.6 mm (1/16") expansion gap is left at the bottom of the socket before welding. In ASTM A333 Gr 6, 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 | Carbon and low-alloy flanges carry most utility, hydrocarbon and high-temperature service. ASTM A333 Gr 6 is picked for cold-climate and refrigerated piping down to −45 °C. |
|---|---|
| Typical service | LNG & refrigeration — Cold process lines. |
| B16.5 material group | 1.1 — A350 LF2 flanges are impact-tested for low-temperature service. |
| Bolting | ASTM A320 L7 studs with A194 Gr 7L nuts |
| Welding to carbon steel | Matching carbon or low-alloy filler is used; joints to stainless need ER309L |
| Matching filler | E7018-1 / ER80S-Ni1 |
ASTM A333 Gr 6 Socket Weld Flange Chemical Composition
Under technical review for TDS.
| Element | Current requirement |
|---|---|
| Carbon | As specified |
| Manganese | As specified |
| Silicon | 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 A333 Grade 6.
ASTM A333 Gr 6 Socket Weld Flange Mechanical Properties
Under technical review for TDS.
| Property | Current requirement |
|---|---|
| Tensile strength | As specified |
| Yield strength 0.2% | As specified |
| Elongation | As specified |
| Charpy impact | 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 A333 Grade 6 — condition per order.
Full chemistry, properties and equivalents are on the ASTM A333 Gr 6 grade page.
Other ASTM A333 Gr 6 flanges
ASTM A333 Gr 6 Socket Weld 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.
ASTM A333 Gr 6 Socket Weld Flange — questions buyers ask
Why leave a gap in a socket weld?
The gap lets the pipe expand during welding without cracking the fillet weld. ASME B31.3 requires it.
What pressure rating does a ASTM A333 Gr 6 socket weld flange have?
It depends on class and temperature. ASTM A333 Gr 6 forgings are in ASME B16.5 material group 1.1; read your class column in that group's table at the design temperature.
Can ASTM A333 Gr 6 socket weld flanges be welded to carbon steel?
Yes — matching carbon or low-alloy filler is used; joints to stainless need ER309L.
Which standard covers ASTM A333 Gr 6 socket weld flanges?
The material is ASTM A350 LF2; dimensions follow ASME B16.5. Always state both on your purchase order, with the edition if your project specifies one.
What decides the price of a ASTM A333 Gr 6 socket weld flange?
The steel 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