ASTM A333 Gr 6 Weld Neck FlangeASTM A350 · ASME B16.5 · Manufacturer, trader & exporter, India
SA-333 Gr 6 · Low-temperature carbon steel pipe · WNRF
An ASTM A333 Gr 6 weld neck flange is a flange with a long tapered hub that is butt-welded to the pipe, for use with ASTM A333 Gr 6 pipe. ASTM A333 Gr 6 itself is a pipe or plate specification, so the matching weld neck flange is made to ASTM A350 LF2 — which is what we supply for A333 Gr 6 lines. Choose a weld neck flange for high pressure, high or low temperature and cyclic loading. The tapered hub moves stress away from the flange face, and the full-penetration butt weld can be radiographed.
- 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 Weld Neck Flange?
- What it is
- A flange with a long tapered hub that is butt-welded to the pipe
- Material
- ASTM A350 LF2
- Dimensions
- ASME B16.5 · B16.47
- Grade
- ASTM A333 Gr 6
- Best at
- Cold-climate and refrigerated piping down to −45 °C
ASTM A333 Gr 6 Weld Neck Flange Specification
| Product | ASTM A333 Gr 6 Weld Neck Flange |
|---|---|
| Material standard | ASTM A350 LF2 |
| Dimensional standard | ASME B16.5 · B16.47 |
| 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 Weld Neck Flange
Choose a weld neck flange for high pressure, high or low temperature and cyclic loading. The tapered hub moves stress away from the flange face, and the full-penetration butt weld can be radiographed.
- Bore must match the pipe schedule — state it on the order
- Hub length and taper per ASME B16.5 / B16.47 tables
- Most common facing: raised face; RTJ for high-pressure classes
More on choosing: Weld neck flange guide.
ASTM A333 Gr 6 Weld Neck Flange: Why A333 Gr 6 for weld neck flanges
Choose a weld neck flange for high pressure, high or low temperature and cyclic loading. The tapered hub moves stress away from the flange face, and the full-penetration butt weld can be radiographed. 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 Weld Neck 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 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 |
| 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 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.
ASTM A333 Gr 6 Weld Neck Flange — questions buyers ask
Why is the bore important on a weld neck flange?
The flange bore is machined to the inside diameter of the pipe schedule, so the weld is smooth inside. A wrong bore leaves a step that disturbs flow and complicates the weld.
What pressure rating does a ASTM A333 Gr 6 weld neck 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 weld neck 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 weld neck flanges?
The material is ASTM A350 LF2; dimensions follow ASME B16.5 · B16.47. 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 weld neck 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