Forged Flanges Suppliers

Choosing the right pressure class (also known as flange rating) is essential to ensure safety, system compatibility, and compliance with international standards.

Here’s how to select the right pressure class for forged flanges:

Understand the Operating Conditions

1. Pressure and temperature are the key deciding factors.
2. Higher temperature generally reduces pressure-handling capability, so consult pressure-temperature rating charts of standards like ASME B16.5.
3. Example: A Class 300 flange may handle 740 psi at 100°F, but only 570 psi at 400°F.

Refer to International Standards

1. Most forged flanges follow ASME, EN, or DIN standards.
2. Common pressure classes include 150, 300, 600, 900, 1500, and 2500 in ASME; PN6 to PN400 in European standards.
3. Always check the flange standard and face type when selecting class.

Material Compatibility

1. Pressure class varies by material grade. For example, Carbon Steel flanges may have different ratings than Stainless Steel at the same temperature.
2. Ensure material's allowable stress aligns with operating pressure.

Application & Safety Factors

1. Consider any surge pressure, pulsation, or cyclic loading.
2. Applications like steam lines, offshore platforms, or chemical reactors may require higher class flanges with enhanced safety margins.

The surface finish of a forged flange directly affects its sealing ability, gasket compatibility, and long-term performance in pressure systems. Choosing the right finish ensures leak-proof joints and prevents issues during installation.

Common Surface Finishes for Forged Flanges:

1. Stock Finish (Standard Finish)
   • Most widely used finish for raised face flanges.
   • Achieved by spiral machining with a 1.6 to 3.2 μm roughness.
   • Compatible with soft gasket materials (spiral wound, compressed fiber).
2. Smooth Finish
   • Machined with minimal tool marks (Ra ≤ 1.6 μm).
   • Used for metallic or soft gaskets in low-pressure, non-cyclic systems.
   • Ensures metal-to-metal contact without damaging sealing surface.
3. Spiral Serrated Finish
   • Machined spiral grooves with deeper cuts than stock finish.
   • Provides better grip and anti-blowout protection.
   • Ideal for high-vibration or cyclic pressure applications.
4. Concentric Serrated Finish
   • Multiple concentric grooves provide uniform gasket seating.
   • Preferred in vacuum, gas, and steam systems requiring tight seals.

Always match the surface finish with the gasket material and application pressure to ensure long-term joint integrity.

Forged flanges are thoroughly tested and inspected to ensure they meet global standards and are safe for high-pressure, critical service environments.

Key Testing & Inspection Procedures:

1. Visual & Dimensional Check
   • Confirms surface finish, flange face, thickness, bolt holes, and overall dimensions per ASME/EN/DIN standards.
2. Hydrostatic Pressure Test
   • Ensures the flange withstands rated pressure without leakage or deformation.
3. PMI Test (Positive Material Identification)
   • Verifies the correct chemical composition, especially for stainless steel and alloy flanges.
4. Ultrasonic Testing (UT) / Magnetic Particle Inspection (MPI)
   • Detects internal defects like cracks or voids, as required in critical applications.
5. NACE Compliance (If Required)
   • Ensures material is suitable for sour service as per NACE MR0175 / ISO 15156.
6. Third-Party Inspection (TPI)
   • Optional review by Lloyd’s, BV, SGS, etc., based on client requirements.

Documents & Certifications Provided:

• EN 10204 3.1 / 3.2
• Heat numbers & traceability
• Dimensional reports & inspection release note

Forged flanges are preferred over other flange types due to their exceptional strength, reliability, and performance under demanding industrial conditions. They're widely used in oil & gas, petrochemical, chemical, power generation, marine, and offshore sectors.

Key Advantages of Forged Flanges:

1. Superior Strength & Durability
   • Forging aligns the grain structure of the metal, giving the flange higher tensile strength and fatigue resistance compared to cast or machined alternatives.
2. Better Structural Integrity
   • The forging process reduces internal voids, porosity, and inclusions — making the flange more reliable under cyclic loads or vibration.
3. High Pressure & Temperature Resistance
   • Ideal for applications in extreme conditions, forged flanges maintain integrity in Class 150 to Class 2500 pressure ratings and high thermal environments.
4. Dimensional Accuracy
   • Forged flanges offer tighter tolerances and better surface finishes, resulting in leak-proof connections when installed with appropriate gaskets.
5. Enhanced Safety & Lifespan
   • Due to their strength and resistance to failure, forged flanges reduce the risk of leaks, joint failure, or unplanned downtime, especially in hazardous pipelines.
6. Versatility in Design
   • Available in a wide range of standards (ASME, EN, DIN, JIS) and facing types (RF, FF, RTJ) to suit various piping systems.
7. Cost-Effective in the Long Term
   • Though slightly costlier upfront, their longer service life and reduced maintenance requirements make them a cost-efficient choice over time.

At Nutech, forged flanges are manufactured using closed-die forging methods under strict quality control to ensure dimensional accuracy, mechanical strength, and reliability.

Step-by-Step Forged Flange Manufacturing Process:

1. Raw Material Selection
   • High-grade billets, blooms, or ingots are selected as per customer requirements — typically carbon steel, stainless steel, or alloy steels.
2. Heating the Metal
   • The raw metal is heated to the forging temperature (usually 1100°C–1250°C) in a controlled furnace.
3. Die Forging / Upset Forging
   • The hot metal is shaped under high pressure using closed dies or hammers. This aligns the grain flow, giving the flange excellent strength.
4. Trimming & Flash Removal
   • Excess material (flash) around the edges is removed to achieve the required shape and dimensions.
5. Heat Treatment (If Required)
   • The forged flange undergoes normalizing, quenching, tempering, or annealing to enhance its mechanical properties.
6. Rough & Finish Machining
   • Machining is done on CNC or lathe machines to achieve precise tolerances, facing (RF, FF, RTJ), and drilling bolt holes per standards.
7. Inspection & Testing
   • Visual, dimensional, and non-destructive tests like UT/MPI are performed. Chemical analysis and mechanical testing are conducted if required.
8. Marking & Surface Protection
   • Flanges are marked with heat number, size, class, and material. Coated with black paint, anti-rust varnish, or galvanized as per client request.
9. Packing & Documentation
   • Final products are packed in seaworthy wooden boxes with traceability documents, inspection reports, and compliance certificates.

Nutech is a globally trusted manufacturer and exporter of forged flanges, serving a wide range of industries across multiple continents. Our forged flanges are recognized for their high precision, quality, and compliance with international standards.

We export forged flanges to over 45 countries, including:

• Middle East: UAE, Saudi Arabia, Oman, Kuwait, Qatar, Bahrain, Iraq
• Europe: Germany, Italy, France, Spain, Netherlands, UK, Poland
• Africa: Egypt, Nigeria, Algeria, South Africa, Kenya
• Asia-Pacific: Singapore, Malaysia, Indonesia, Thailand, Vietnam, Philippines
• South Asia: Sri Lanka, Bangladesh, Nepal, Maldives
• North America: USA, Canada, Mexico
• South America: Brazil, Argentina, Chile, Peru
• CIS Countries: Kazakhstan, Uzbekistan, Azerbaijan, Russia
• Oceania: Australia, New Zealand