Product Overview
Carbon steel weld neck flange is a forged or plate flange with a long tapered hub that is butt-welded directly to the pipe. The hub provides excellent stress distribution and makes the weld neck flange the strongest and most fatigue-resistant flange type for high-pressure and high-temperature service. Huaxia-Steel supplies carbon steel weld neck flanges from 1/2″ to 48″ in ASME/ANSI classes 150 through 2500, to ASTM A105, A105N, A350 LF2, and A694 F52 – F65.
Specifications
| Parameter | Range | Standard / Tolerance |
|---|---|---|
| Size | 1/2″ – 48″ (DN15 – DN1200) | ASME B16.5 (≤ 24″), B16.47 (≥ 26″) |
| Pressure class | CL150 – CL2500 | Per ASME B16.5 dimensional tables |
| Material | A105, A105N, A350 LF2/LF3, A694 F52-F65 | ASTM A105 / A350 / A694 |
| Facing | RF, RTJ, FF, TG | ASME B16.5 |
| Bore | STD, XS, XXS, Schedule matched | Per pipe schedule |
| Marking | Size, class, material, heat number, standard | Stamped or inked |
Available Grades
| Standard | Grade | Service |
|---|---|---|
| ASTM A105 | A105 / A105N | General pressure, ambient to 538°C |
| ASTM A350 | LF2, LF3 | Low-temperature service below −29°C |
| ASTM A694 | F52, F60, F65, F70 | High-strength transmission pipeline |
| EN 1092-1 | P250GH, P245GH, P280GH | European pressure equipment |
Manufacturing Standards
- Forging: raw billet or bar is heated and forged to shape, then normalized or quenched and tempered as required.
- Machining: facing, bore, bolt holes, and hub are finish-machined on CNC lathes and drills.
- Dimensional control: OD, thickness, hub length, bore, bolt circle, and facing per ASME B16.5 or B16.47.
- Non-destructive testing: ultrasonic or magnetic particle testing on request for critical service.
Applications
- Process piping and pressure vessels
- Oil and gas transmission pipelines
- Power generation and steam systems
- Chemical and petrochemical plants
- Offshore platforms and subsea manifolds
- Refinery and LNG facilities
Quality Assurance
- EN 10204 3.1 certificate with heat traceability
- Chemical and mechanical test reports per ASTM A105
- Dimensional report including bore, OD, thickness, and bolt circle
- Surface inspection and hardness check
- Optional UT, MT, PT, or hydrostatic testing
- Third-party inspection by SGS, BV, TÜV on request
Packaging & Shipping
- Wooden pallets or plywood cases
- Flange faces protected with cardboard or rubber inserts
- Threaded bolt holes protected with plastic plugs
- Heat-numbered packing list attached to each case
- Container or sea bulk loading with tally and photos
Huaxia-Steel supplies carbon steel weld neck flanges to ASME B16.5 and B16.47, classes 150 – 2500, in A105, A105N, A350 LF2, and A694 grades, RF/RTJ facing. Send us your flange list with size, class, material, and facing for a 24-hour factory-direct quotation.
