FORGED FLANGES
Songjie Forging is a professional forged flange manufacturer and supplier in China. Backed by our in-house steelmaking facilities and open-die forging capabilities, we manufacture a wide range of custom forged flanges, including weld neck flanges, blind flanges, slip-on flanges, lap joint flanges, threaded flanges, and socket weld flanges. We work with various materials, including carbon steel, alloy steel, stainless steel, and duplex stainless steel.
Our production facilities are equipped with electric arc furnaces (EAF), ladle refining furnaces (LF), vacuum degassing (VD) systems, large open-die forging presses, and machining equipment. This enables us to control the entire manufacturing process, from steelmaking and heat analysis to final precision machining of the flange sealing faces.
Forged flanges are ring-shaped forged components used to connect pipes, valves, pressure vessels, and various types of industrial equipment. They are widely used in the petrochemical, oil and gas, power generation, water treatment, shipbuilding, metallurgy, mining, and heavy machinery industries. During service, flanges must withstand bolt preload, internal system pressure, and thermal cycling. Manufacturing processes such as open-die forging, closed-die forging, and seamless ring rolling help produce continuous grain flow and a dense internal microstructure, giving forged flanges excellent strength, toughness, and pressure-retaining integrity.
Each flange is forged under a controlled forging ratio and subsequently undergoes heat treatment and precision machining. To ensure product quality, we perform a range of inspections and tests, including ultrasonic testing (UT), magnetic particle testing (MT), hardness testing, and dimensional inspection. Each shipment is supplied with material test certificates (MTCs) traceable to the corresponding heat numbers, together with complete non-destructive testing (NDT) reports. Our products are manufactured and inspected in accordance with applicable international and national standards, including ASTM, ASME B16.5 / B16.47, ISO, DIN, JIS, and GB/T, as specified by customer requirements.
FORGED FLANGE TYPES WE MANUFACTURE
| Flange Type | Description |
|---|---|
| Weld Neck Flange (WN) | Features a long tapered hub and connects to the pipe by butt welding. |
| Blind Flange (BL) | A solid disc-shaped flange used to seal off pipelines, vessels, or equipment openings. We can manufacture large-diameter and heavy-wall blind flanges to meet demanding pressure and sealing requirements. |
| Slip-On Flange (SO) | Also known as a plate flange or slip-on welding flange. Secured by two fillet welds — one inside and one outside. A cost-effective option widely used in general industrial piping systems. |
| Lap Joint Flange (LJ) | Consists of a stub end and a loose backing flange — easy to align and bolt. |
| Socket Weld Flange (SW) | Suitable for small-bore, high-pressure piping. |
| Threaded Flange (THD) | Welding-free connection, used on small-bore pipework. |
| Long Weld Neck Flange (LWN) | Features an extended neck for pressure vessel and equipment nozzle connections. |
| Orifice Flange (ORF) | Specifically designed for orifice plate installations in flow measurement systems. It typically includes pressure tap connections and jack bolts for convenient orifice plate installation and removal. |
| Reducing Flange (RED) | Connects pipes of two different nominal sizes. |
| Spectacle Blind Flange (Figure-8 Blind) | A combination component consisting of a solid blind plate and an open spacer. It provides a convenient way to switch between open and closed pipeline configurations for maintenance and isolation. |
| Anchor Flange (AF) | Used to anchor buried pipelines and restrain axial thrust and pipe movement. |
| Girth Flange (GF) | Designed for circumferential connections between cylindrical pressure vessel shell sections, providing a strong and secure connection for large industrial vessels. |
| Custom Non-Standard Forged Flanges | We manufacture custom-designed and special-shaped forged flanges according to customer drawings, technical specifications, material requirements, and application conditions. |
MATERIALS
- Carbon Steel (A105, 20#, 45#, A36, S355J2+N, etc.)
- Alloy Steel (42CrMo4, 4140, 4340, 40Cr, 35CrMo, F11, F22, etc.)
- Tool Steel (4Cr5MoSiV1, H13, S7, 5CrNiMo, etc.)
- Stainless Steel (304, 316L, 17-4PH, etc.)
- Duplex and Super Duplex Stainless Steels
- Aluminum
- Titanium
- Specialty Steels and Custom Grades
SIZE RANGE
Maximum Outside Diameter (OD): 9,000 mm
Pressure Ratings (ASME B16.47)
• Series A — Class 150 / 300 / 400 / 600 / 900 (NPS 26–60; Class 900 up to NPS 48)
• Series B — Class 75 / 150 / 300 / 400 / 600 / 900 (Classes 400–900 up to NPS 36)
WEIGHT RANGE
Up to 80,000 lb (40 short tons)
FORGED FLANGE MANUFACTURING PROCESS
1. Raw Material Verification: Heat number cross-check, chemical composition analysis via OES (Optical Emission Spectrometer), and PMI (Positive Material Identification) non-destructive testing of incoming steel billets.
2. Cutting and Billet Preparation: Saw cutting according to forging weight, with allowance reserved for subsequent machining.
3. Heating: Heating to specified temperature in a controlled furnace followed by soaking to ensure uniform core temperature.
4. Forging / Ring Rolling: Upsetting and punching; near-net-shape forming by means of die forging, open-die forging elongation, or radial-axial ring rolling.
5. Trimming / Finishing / Cooling: Removal of flash, facing alignment, and controlled cooling rate.
6. Heat Treatment: Normalizing or quenching and tempering according to material grade; stress-relief annealing after ring rolling.
7. Testing: Hardness check, visual inspection, preliminary dimensional verification, heat-treatment record review, and mechanical property specimen testing.
8. Rough Machining: Boring, OD and facing machining with consistent stock left for finishing.
9. UT Inspection: High-grade ultrasonic testing shall only be performed after rough turning to remove scale.
10. Finish Machining: Machining of sealing faces, bolt holes, bores, outer diameters and other features.
11. Final Inspection: Verification of dimensions, hardness, surface roughness, thread gauging, marking, etc.
12. Surface Treatment & Packaging: Rust prevention, sealing face protection, and export packaging complying with ocean shipment and customer requirements.
FLANGE QUALITY CONTROL & INSPECTION
Quality control is essential to ensuring the dimensional accuracy, material integrity, and mechanical performance of custom forged flanges. At Songjie Forging, we arrange inspections and testing according to applicable standards, customer drawings, and project-specific technical specifications.
Chemical Composition Analysis
Chemical analysis is performed on all incoming materials to verify compliance with the specified material grade.
Mechanical Property Testing
Tensile strength, yield strength, elongation and impact properties are evaluated as required by the relevant material specifications.
Hardness Testing
Hardness inspection is carried out on forged flanges upon completion of the specified heat treatment.
Ultrasonic Testing (UT)
Assesses internal material integrity and identifies potential internal flaws against established acceptance criteria.
Magnetic Particle Testing (MT)
Detects surface and near-surface discontinuities for ferromagnetic materials.
Liquid Penetrant Testing (PT)
Used when required to reveal surface-breaking defects on non-porous materials.
Dimensional Inspection
Verifies outer diameter, inner bore, thickness, bolt hole positions, bolt circle diameter, flange sealing faces and other critical dimensions.
Surface Roughness
Roughness measurements are taken for Raised Face (RF) and Ring-Type Joint (RTJ) faces, with records maintained by batch.
WHAT SERVICES WE PROVIDE FOR YOU - WHY YOU CAN TRUST US
- If you got a forged flange problem from other suppliers, with our professional engineering team, we can solve the problem and help you for the next project.
- With 20+ years of experience and our own steel factory, we can make the best forging flanges with low cost and high properties.
- Take professional heat treating and processing, forged flanges will have the best properties to satisfy your project needs.
- Provide custom service, manufacture products with uncommon size.
- No minimum order quantities, shortest leading time.
FAQ About Forged Flanges
We produce forged flanges to ASME B16.5, ASME B16.47, EN 1092‑1, DIN, JIS, BS and other international standards. Flanges made against customer drawings and project‑specific technical specifications are also acceptable.
Forged steel flanges manufactured with proper forging and heat treatment deliver superior structural integrity and mechanical performance. They are widely used across many industrial sectors, especially for service conditions requiring reliable joints under pressure, temperature and mechanical loads.
Yes. We evaluate custom forged flange blanks and assemblies based on customer drawings, technical specifications, material requirements and project service conditions.
Custom machining is available per drawings and technical requirements, including CNC turning, facing, boring, bolt‑hole drilling and more (subject to production capacity).
Please provide flange drawings or applicable standards, material grade, dimensions, pressure class, quantity, heat treatment requirements, inspection specifications, destination and other relevant details. Our team will review your requirements and prepare a quotation accordingly.