ASTM A106 Gr.B Carbon Steel Studded Tube with CS Studs
Introduction to ASTM A106 Gr.B + CS Studded Tubes
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.
Structure of Carbon Steel Studded Tube (Base Tube A106 Gr.B & CS Studs)
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.
Chemical Composition of ASTM A106 Gr.B Base Tube and Carbon Steel Studs
ASTM A106 / ASME SA106 Grade B Base Tube Chemical Composition (wt%)
| Element |
Requirement |
| Carbon (C) |
≤ 0.30 |
| Manganese (Mn) |
0.29 – 1.06 |
| Phosphorus (P) |
≤ 0.035 |
| Sulfur (S) |
≤ 0.035 |
| Silicon (Si) |
≥ 0.10 |
| Chromium (Cr) |
≤ 0.40 |
| Copper (Cu) |
≤ 0.40 |
| Molybdenum (Mo) |
≤ 0.15 |
| Nickel (Ni) |
≤ 0.40 |
| Vanadium (V) |
≤ 0.08 |
| Note |
Cr + Cu + Mo + Ni + V ≤ 1.00 |
Mechanical Properties of ASTM A106 Gr.B
| Property |
Minimum Value |
| Tensile Strength |
415 MPa (60 ksi) |
| Yield Strength |
240 MPa (35 ksi) |
| Elongation (longitudinal) |
≥ 30% |
Carbon Steel (CS) Stud Material
Typically low-carbon steel equivalent to Q235B, ASTM A510 (grades 1005–1010), or similar mild steel. Typical composition (wt%):
| Element |
Typical Range |
| C |
0.08 – 0.20 |
| Mn |
0.30 – 0.70 |
| Si |
≤ 0.35 |
| P |
≤ 0.045 |
| S |
≤ 0.045 |
Stud material can be matched or upgraded according to customer specifications.
Dimensional Tolerances and Specification Range of A106 Gr.B CS Studded Tubes
| Parameter |
Standard Range |
Typical Tolerance / Notes |
| Base Tube OD |
25 – 219 mm (1" – 8" NPS) |
Per ASTM A106 / ASME B36.10M |
| Wall Thickness |
3.5 – 20 mm (Sch 40 – Sch 160) |
±12.5% or as agreed |
| Tube Length |
Up to 15–28 m |
Custom cut lengths available |
| Stud Diameter |
6 – 25.4 mm (0.25" – 1") |
± 0.3 mm typical |
| Stud Height |
10 – 38 mm (0.4" – 1.5") |
± 0.5 mm typical |
| Stud Pitch (longitudinal) |
8 – 30 mm |
Customizable; common 15.875 mm (63 studs/m) |
| Stud Arrangement |
Square, hexagonal, or staggered rows |
Vertical or angled to tube surface |
| Bare Ends |
As required (usually 50–150 mm each end) |
— |
All dimensions can be customized according to drawings or process requirements. Strict dimensional control and 100% visual + random pull-off testing of studs are performed.
Performance Advantages of A106 Gr.B CS Studded Tubes
- Heat transfer area increased by 2–3 times compared with bare tubes, significantly improving flue-gas side heat transfer coefficient.
- Extremely strong metallurgical bond between stud and tube — resistant to vibration, thermal shock, and aggressive mechanical cleaning.
- Excellent resistance to fouling and ash deposition in dirty flue-gas environments; easy to clean.
- Suitable for high-temperature service (up to approximately 550–600 °C depending on design).
- High mechanical strength and pressure-bearing capacity of the A106 Gr.B base tube.
- Cost-effective solution for corrosive and particulate-laden gas streams where conventional thin-fin tubes would fail rapidly.
- Reduced overall equipment size and improved energy efficiency in waste-heat recovery systems.
Applications of ASTM A106 Gr.B Studded Fin Tubes
- Convection sections of tubular heating furnaces in petrochemical and refining plants
- Fired heaters, reforming furnaces, and steam-cracking furnaces
- Boiler economizers and air preheaters (especially coal-fired, biomass, and waste-to-energy boilers)
- Waste heat recovery units (WHRU) and heat recovery steam generators (HRSG)
- Process gas coolers and sulfur recovery units (SRU)
- Fluid catalytic cracking unit (FCCU) regenerators and coker heaters
- Chemical reactors and high-dust flue-gas heat exchangers
Our Advantages and Manufacturing Experience
As a specialized manufacturer and exporter of heat-transfer tubes, we have extensive experience in producing ASTM A106 Gr.B carbon steel studded tubes for global petrochemical, power, and process industries.
Key strengths include:
- Fully automatic PLC-controlled resistance welding lines ensuring consistent stud quality and density
- Strict raw-material control with full Mill Test Certificates (EN 10204 3.1 / 3.2)
- Comprehensive quality system covering dimensional inspection, weld integrity testing, hydrostatic testing, and surface protection
- Ability to supply complete sets according to customer drawings, including U-bends, coils, and tube bundles
- Flexible production capacity and competitive lead times for both standard and customized orders
- Experience serving major EPC contractors and end-users in Asia, Middle East, Europe, and the Americas
We welcome detailed inquiries with drawings or process data. Our engineering team can provide technical support for material selection, stud configuration optimization, and thermal performance estimation.
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