Carbon Steel Flange — Factory Direct Supplier | Huaxia-Steel
Huaxia-Steel supplies carbon steel flanges in types Weld Neck, Slip On, Blind, Socket Weld, Threaded, and Lap Joint per ASME B16.5, B16.47, EN 1092-1, and JIS B2220 standards. Manufacturing methods include forging, plate cutting, and bar stock machining, with full traceability from raw material to finished product. Pressure ratings cover Class 150 through Class 2500 and PN6 through PN400.
Product Overview
Carbon steel flanges provide detachable connections in pipelines, pressure vessels, and process equipment. The most common material grades are A105 ( forged), A350 LF2 (low temperature), and A181 (general purpose). Selection depends on pressure-temperature rating, corrosion environment, and code requirements (ASME Section VIII, B31.3, etc.).
Specifications
| Parameter | Standard Range |
|---|---|
| Nominal Size | 1/2″ – 80″ (DN15 – DN2000) |
| Pressure Rating | Class 150 – 2500 / PN6 – PN400 |
| Face Types | RF, FF, RTJ, TG, MF |
| Bore | Schedule 10 – XXS |
| Wall Thickness | Per ASME B16.5 / EN 1092-1 tables |
| Coating | Black paint, yellow varnish, hot-dip galvanized, epoxy |
Available Grades
| Grade | Standard | Service Temp | Application |
|---|---|---|---|
| A105 / A105N | ASTM A105 | -29°C to 425°C | General purpose, oil & gas |
| A350 LF2 / LF3 | ASTM A350 | -46°C to 343°C | Low temperature service |
| A181 Class 60 / 70 | ASTM A181 | Up to 480°C | Non-critical piping |
| S235JR / P245GH | EN 1092-1 | -10°C to 400°C | European standard projects |
| SS400 / S25C | JIS B2220 | Up to 350°C | Japanese standard, Asian projects |
Manufacturing Standards
- ASME B16.5: Pipe flanges and flange fittings (NPS 1/2 through 24)
- ASME B16.47: Large diameter steel flanges (NPS 26 through 60)
- EN 1092-1: Circular flanges for pipes, valves, fittings (European standard)
- JIS B2220: Steel pipe flanges (Japanese standard)
- API 605: Large line welded end flanges (petrochemical)
- MSS SP-44: Steel pipeline flanges
Flange Types and Selection
| Type | Connection Method | Best For |
|---|---|---|
| Weld Neck | Butt weld to pipe | High pressure, cyclic loading, critical service |
| Slip On | Filleted inside and outside | Low pressure, easy alignment, cost-sensitive |
| Blind | Bolted, no bore | Terminations, pressure testing, isolation |
| Socket Weld | Pipe inserted, fillet welded | Small bore (≤ 2″), high pressure |
| Threaded | NPT/BSPT connection | Non-welded assembly, maintenance access |
| Lap Joint | Used with stub end | Frequent dismantling, alignment tolerance |
Applications
- Oil & gas pipelines: Transmission and distribution lines, compressor stations
- Petrochemical plants: Process piping, reactor connections, heat exchangers
- Power generation: Steam lines, feedwater piping, turbine connections
- Water treatment: Pump stations, filtration systems, distribution mains
- Shipbuilding: Bilge, ballast, and fuel oil lines per classification society rules
- Structural: Bridge bearings, temporary works, architectural connections
Quality Assurance
- Material certification: Mill test certificates per ASTM/EN/JIS with full chemical and mechanical data
- Forging inspection: Ultrasonic testing per ASTM A388 or EN 12668 for sizes ≥ NPS 4
- Dimensional check: OD, bore, thickness, bolt circle, facing finish verified per standard tables
- Surface finish: RF serration checked (125 – 250 AARH typical); RTJ groove dimensions with go/no-go gauges
- Pressure testing: Hydrostatic shell test at 1.5× design pressure available on request
- Positive material identification (PMI): XRF spectrometry to confirm grade before shipment
Packaging and Shipping
- Individual wrapping: Each flange wrapped in PE film; mating faces protected with plywood or plastic caps
- Palletization: Same-size flanges stacked on plywood pallets, steel-strapped; max 2,000 kg per pallet
- Marking: Size, rating, grade, heat number, standard stamped on OD or tagged
- Container loading: 20’GP: 18 – 22 MT; 40’HC: 24 – 26 MT
- Export coating: Rust-preventive oil + polyurethane varnish (RAL colors on request)
Request a quotation specifying flange type, size, pressure rating, material grade, face finish, and quantity. Huaxia-Steel provides technical drawings, MTRs, and third-party inspection coordination.
