Socket Weld flange

SVR Global manufactures Socket Weld Flanges across the USA, engineered for high pressure, small bore piping systems that demand a leak tight, smooth bore connection. Our facility produces these flanges in carbon steel, stainless steel, alloy steel, duplex, super duplex, and nickel alloy grades, machined and finished to ASME and ASTM specifications.

What is a Socket Weld Flange?

A Socket Weld Flange is pipe flange which features a socket in which the pipe is inserted before the fillet welding process is performed on the outer circumference. This method of joining differs from that used in butt welding as the weld does not enter the inner portion of the bore.

Working Principle:

1. Pipe insertion into socket bore - Insert the pipe into the recessed bore of the flange, making sure that the pipe reaches the internal shoulder.

2. Controlled clearance - Pull back the pipe by a certain distance (about 1.6 mm/1/16”) before welding to accommodate thermal expansion of the pipe.

3. External fillet weld - A single fillet weld is deposited around the outer circumference where the pipe meets the flange hub, forming a permanent joint.

4. No internal weld exposure - Since the weld sits outside the bore, the internal flow path remains smooth and free of weld penetration.

5. Bolted connection to mating flange - The flange face (raised face, flat face, or other finish) is bolted to a mating flange with a gasket in between to complete a sealed pipe connection.

6. Load transfer - Once bolted and torqued, the flange transfers pipe end loads (pressure, weight, thermal expansion) through the bolt circle into the connecting pipework.

Design and Construction Features:

• Recessed socket bore: sized to accept the pipe OD with a controlled bottom clearance, typically 1.6 mm (1/16"), to absorb thermal expansion and prevent root stress during welding.

• Single fillet weld: applied externally at the pipe to flange interface, eliminating the need for internal weld access.

• Raised face or flat face options: manufactured to match gasket and mating flange requirements.

• Bore tolerance control: held tight to ensure alignment accuracy and minimal fit up gap.

Manufacturing Process:

1. Raw material selection: Forged billets tested for chemical composition and mechanical properties before machining.

2. Forging: Flanges are open die or closed die forged to achieve grain flow and structural integrity.

3. Heat treatment: Normalize, anneal, or quench and temper based on the grade of the metal and its application.

4. CNC machining:  The bore, face, and bolt holes are cut in accordance with ASME B16.5 or ASME B16.11 specifications.

5. Surface finishing: Facing finish is controlled per serrated, smooth, or spiral finish requirements.

6. Marking and traceability: Heat number, grade, size, and pressure class are stamped for full material traceability.

Governing Standards and Specifications:

• Dimensional standard: ASME B16.11

• Facing standard: ASME B16.5

• Material standards: ASTM A105, ASTM A350 LF2, ASTM A182 (F304/F304L, F316/F316L, F11, F22, F91), ASTM A182 F51/F53 (duplex and super duplex), ASTM B564 (nickel alloys)

• Pressure classes: Class 150 to Class 2500

• Testing standards: NDT, hydrostatic testing, and PMI verification as per project specification

Materials Manufactured:

Size and Pressure Range:

• Nominal Bore: 1/2" to 4" (larger sizes available on request)

• Pressure Class: 150#, 300#, 600#, 900#, 1500#, 2500#

• Bore Schedule: SCH 40, SCH 80, SCH 160, XXS, matched to pipe schedule

Quality Control and Testing:

• Chemical composition analysis (spectrometer testing)

• Mechanical testing - tensile, hardness, and impact testing

• Non destructive testing - dye penetrant (DPT), magnetic particle (MPI), ultrasonic (UT)

• Dimensional inspection against ASME B16.11 tolerances

• Third party inspection and material test certificates (MTC) per EN 10204 3.1/3.2

Socket Weld Flange Applications:

Socket Weld Flanges from SVR Global are used in high pressure, small diameter piping across:

• Oil and gas extraction and transport lines

• Petrochemical processing units

• Power generation plants, including thermal and nuclear steam lines

• Chemical processing plants

• Offshore and marine piping systems

• Instrumentation, hydraulic, and pneumatic control lines

• Shipbuilding piping networks

Advantages of Socket Weld Flanges:

• Smooth internal bore with no weld penetration, reducing turbulence and erosion

• Easier alignment during fabrication due to the self locating socket

• Suitable for high pressure service in smaller pipe diameters

• Faster fabrication compared to butt weld joints, since radiography is not required

• Strong mechanical joint strength in small bore applications