ASTM A106 Gr.B Studded Tube for Steam Reforming Furnace and Waste Heat Recovery

Studded tubes, also known as nail-head tubes, pin tubes, or studded fin tubes, are high-efficiency extended-surface heat transfer elements. Our ASTM A106 Gr.B carbon steel studded tubes consist of a seamless base tube manufactured to ASTM A106 / ASME SA106 Grade B, with solid carbon steel (CS) studs resistance-welded onto the outer surface. These tubes significantly increase the external heat transfer area, typically 2–3 times that of a bare tube, while maintaining excellent mechanical strength and resistance to fouling and aggressive cleaning. They are widely used in high-temperature, high-pressure, and corrosive flue-gas environments in the petrochemical, power generation, and process industries.

The structure comprises three key elements:

• Base Tube – Seamless carbon steel pipe conforming to ASTM A106 Gr.B / ASME SA106 Gr.B, designed for high-temperature service.

• Studs (Fins) – Solid cylindrical (or occasionally elliptical/lens-shaped) carbon steel pins.

• Bonding Process – Fully automatic electrical resistance welding (also called resistance stud welding or forge welding). High current and pressure create a true metallurgical forge weld with full penetration and minimal heat-affected zone. No filler metal is used. The process is PLC-controlled for precise stud height, diameter, pitch, and circumferential density.

This welding method produces a bond stronger than the parent materials, allowing the tubes to withstand severe mechanical cleaning (high-pressure water jetting, shot blasting) and thermal cycling without stud detachment.

The chemical composition of the ASTM A106 / ASME SA106 Grade B base tube is as follows:

The mechanical properties of the base tube are as follows:

The studded tube design and manufacturing parameters are summarized below:

The manufacturing process of ASTM A106 Gr.B studded tubes involves fully automatic electrical resistance welding. The key steps include:

• Raw Material Inspection – Base tubes and studs are inspected for chemical composition, dimensions, and surface quality.

• Tube Preparation – Tubes are cleaned and prepared to ensure proper bonding.

• Stud Welding – Studs are automatically welded to the tube surface using a PLC-controlled resistance welding machine. The welding parameters, including stud height, diameter, pitch, and circumferential density, are precisely controlled.

• Quality Control – Weld integrity is verified through visual inspection and mechanical testing.

ASTM A106 Gr.B studded tubes are widely used in applications requiring high heat transfer efficiency in demanding environments:

• Steam Reforming Furnaces – Convection section tubes for hydrogen and syngas production.

• Waste Heat Recovery Systems – Heat recovery from flue gas and exhaust streams in petrochemical and power plants.

• Fired Heaters – Convection chamber heating in refinery and petrochemical furnaces.

• Boilers – High-pressure boilers for power generation and industrial heating.

• Heat Exchangers – Shell and tube heat exchangers in chemical and petrochemical industries.

• Air Preheaters – Combustion air preheating in industrial furnaces.

• Economizers – Flue gas waste heat recovery for boiler feed water preheating.

• Superheaters – Steam superheating in power generation and process industries.

Each studded tube undergoes inspection and testing in accordance with applicable standards and customer specifications:

• Hydrostatic Test – Performed on the base tube per ASTM A106 requirements.

• Non-Destructive Examination (NDE) – Ultrasonic Testing (UT) and Eddy Current Testing (ET) as specified.

• Dimensional Inspection – Verification of tube OD, wall thickness, stud height, stud diameter, stud pitch, and overall length.

• Material Verification – Positive Material Identification (PMI) and full traceability to mill certificates.

• Visual Inspection – Surface finish, weld quality, and stud integrity.

• Welding Process Control – PLC-controlled welding parameters ensure consistent stud attachment quality.

Each shipment is supplied with complete documentation including:

• Mill Test Certificates (EN 10204 Type 3.1)

• Hydrostatic test reports

• NDE reports (if applicable)

• Dimensional inspection reports

• Welding procedure specifications (WPS) and procedure qualification records (PQR)

• Quantity (number of pieces or weight)

• Base tube outside diameter, wall thickness, and length

• Stud material, height, diameter, and pitch/spacing

• Finned length and unfinned sections (bare ends)

• End preparation (plain ends or beveled ends)

• Delivery period required