Helical Finned Tube — Continuously Welded Spiral ND Steel Fin Tube for Boiler Economizers

Material
A high-frequency resistance welded helical/spiral finned tube produced with an ND steel (09CrCuSb) base tube and optional ND/carbon/stainless fin strip. ND steel is a Cu–Sb–Cr–alloyed low-alloy steel engineered to resist low-temperature sulfuric-acid dew-point corrosion and chloride attack in flue-gas paths, making it ideal for boiler economizers and air preheaters.

Specifications

• Tube OD (bare): 19–63.5 mm (3/4"–2-1/2"); other sizes on request

• Wall thickness: 2.0–8.0 mm

• Fin type: Solid or serrated helical fin, continuous wrap, HFERW bond

• Fin material & thickness: ND steel / carbon steel / stainless; 0.8–3.0 mm typical

• Fin height: 8–20 mm (±1.0 mm after welding)

• Fin pitch (fins per meter): as specified; tolerance +5%/−2%

• Tube straightness (finished finned tube): max deviation 5 mm per 3 m (scaled for shorter lengths)

• Ends: Plain or beveled; specified bare ends length tolerance ±6 mm or one fin spacing, whichever is greater

• Typical base-tube alternatives: SA210 A-1 / GB 20G (carbon), A213 T11/T12 (Cr-Mo), EN 10216-2 P235GH / 16Mo3.

Key Features

• High corrosion resistance at dew point

• Efficient, durable fin-to-tube bond (HFERW)

• Geometric consistency for performance

• Material traceability to ordered standards

Our Advantages

1. Straightness & fit-up — ≤5 mm/3 m finished tube; ≤3 mm/3 m bare tubes

2. Dimensional tolerances — Bare OD ≤±1.0 mm; fin height ±1.0 mm; fin pitch +5%/−2%

3. Weld integrity — Min weld width ≈90% of fin thickness or ≥170 MPa weld tensile; controlled weld interruptions; no PWHT required

4. Right material for flue gas — ND steel specifically targets acid dew-point service in economizers

5. Standards-based alternatives — SA210 A-1 / GB 20G; A213 T11/T12; EN P235GH

Chemical Composition (wt.%)

• 09CrCuSb (ND steel): C ~0.09; Cr 0.30–0.60; Cu 0.20–0.40; Sb 0.05–0.10

• GB 20G: C 0.17–0.23; Si 0.17–0.37; Mn 0.35–0.65; P ≤0.025; S ≤0.015–0.020; residual Cr ≤0.25; Cu ≤0.20

• SA210 A-1: C ≤0.27; Si ≤0.10; Mn ≤0.93 (adjustable with C); P ≤0.035; S ≤0.035

• A213 T11: C ≤0.15; Si 0.50–1.00; Mn 0.30–0.60; P ≤0.025; S ≤0.025; Cr 1.00–1.50; Mo 0.44–0.65

• A213 T12: C ≤0.15; Si 0.50–1.00; Mn 0.30–0.60; P/S ≤0.025 (T12S option S ≤0.045); Cr 1.00–1.50; Mo 0.44–0.65

Mechanical Properties

• SA210 A-1: Tensile ≥415 MPa; Yield ≥255 MPa; Elongation ≥30%

• A213 T11/T12: Tensile ≥415 MPa; Yield ≥205 MPa; elongation per A213 table (size dependent)

• GB 20G: Typical plate/tube levels ~Tensile 410–500 MPa; Yield ≥235 MPa; Elongation ≥24% (verify on MTC)

• 09CrCuSb: Supplier-qualified per order; certified on MTC

Execution Standards

• ASTM/ASME: A213/SA213 (T11, T12), A210/SA210 (A-1)

• EN: EN 10216-2 (P235GH, 16Mo3)

• JIS: G3461 (carbon), G3462 (alloy)

• GOST: 8731/8732 (seamless), 8734 (precision cold-formed)

• Fin-weld reference: International HFERW fin dimensions/tolerances/tests

Application Fields
Power-plant economizers, air preheaters, waste-heat recovery, flue-gas condensers, and industrial heat exchangers in SOx/Cl−-bearing service.

Q: Are you trading company or manufacturer ?

A: manufacturer,also can do trading.

Q: How long is your delivery time?

A: Generally speaking,it is 10-15 days if the goods are in stock,or it is 30-40 days if the goods are not in stock,

it is according to quantity.

Q: Do you provide samples? is it free or extra ?

A: Yes, we could offer the sample for free charge but need pay the cost of freight.

Q: What is your terms of payment ?

A: Payment<=2000USD, 100% in advance. Payment>=2000USD, 30% T/T in advance ,balance before shippment.

If you have another question, pls feel free to contact with me.

Who We are ?

-------A professional steel pipes materials inventor, manufacturer and solution provider
Torich International Limited is a professional manufacturer and exporter of steel pipes materials. It is an international marketing and sales company specialized in steel tubes, which holds the factories of Seamless Steel Tubes with Carbon and Alloy Steel Grade, Welded Precision Steel Tubes,DOM Steel Tubes, Seamless & Welded Stainless Steel Tubes with Nickel and Alloy Steel Grade.
Our factory was established since 1997, with the name of TORICH INTERNATIONAL LIMITED. The factories’ technicians are of great engineering experience in steel pipe industry for more than 20 years, which are in great command of production technology for Cold Drawing and Cold Rolling. So we have strong technician team and manufacturing capability.

What products we do?

------- Invent and produce various Precision Steel Pipes

Our steel pipes cover the following ranges:
Seamless Precision Steel Pipes

Bearing Steel Tubes
Welded Precision Steel Pipes, with DOM production
Seamless Heat Exchanger Steel Pipe
Seamless Boiler Steel Pipes

Honed Tubes

Hydraulic Cylinder Steel Tubes

Hydraulic Telescopic Cylinder Tubes
Seamless Structural Steel Pipes
Seamless Mechanical Steel Pipes
Seamless Alloy Steel Tubes & Pipes
Seamless Stainless Steel tubes
Welded Stainless Steel Tubes
Seamless Stainless Steel Tubes & Pipes
Welded Stainless Steel Tubes & Pipes
Seamless Carbon Steel Tubes & Pipes
Nickel Alloy Steel Tubes & Pipes

What TORICH do:
1. Producing Steel Tubes
2. Selling both on Domestic and International Market
3. Precisely Targeting Customers’ Requirement- Sourcing the right factory for right products for Customers

Products Application:
Oil Cylinders
Air Cylinder, 
Automotive Cylinder Liners
Boilers, Pressure Vessels
Shell & Heat Exchangers
Jack Lifting
Telescopic Systems
Pneumatic Cylinders
Agricultural Machineries

Size range is: 
O.D. 4-350mm, 
W.T. 0.5-30mm, 
Length: according to customer’s requirement and agreement
 

Steel Grade:
Carbon Steel Grade:
ST35.8, ST37.0, ST44, ST52;
E155, E195, E215, E235, E275, E355;
195GH, P235GH, P265GH, P195TR1, P195TR2, P235TR1, P235TR2, P265TR1, P265TR2;
SAE1010, SAE1020, SAE1026, SAE1035, SAE1045;

Carbon steel tube: SA178, A179, A192, A210, SA213, SA214, etc.
Alloy Steel Grade:
T2, T5, T9, T11, T12, T17, T21, T22, T91,T92, 15Mo3,16Mo3, 13CrMo44;
SAE4130, SAE4140, 40Cr, 40Cr4, 10CrMo910, 12CrMo910, 11CrMo910,
25CrMo4, 35CrMo, 35CrMo4, 42CrMo4, 34CrMo4, 20MnV, 20MnV6,20CrMn;
Carbon steel tube: A179,A192,A210,DIN17175,etc.

Bearing Steel Grades:
GCr15 52100 suj2 suj3 100Cr6 SKF3S SKF3S 20CrNiMo 8620H 4118H;

Nickel Alloy Grade:
N02200/2201, N04400, N06600, N06601, N06625, N06852, N06219, N06690, N08800/8810/8811, N08825, N08028, N08535, N08904, N08925, N08926, N010276, N06022, etc.

Austenitic/Super Austenitic Stainless Steel Grade:
304/304L, 316/316L, 314, 321, 347H, 316Ti, 316LMod, 317L/N, 310S, 253MA, 330, 904L, S31254, XM-19, etc. 

Ferrite/Martensite Stainless Steel Grade:
TP410, TP405, TP420, TP430, TP430Ti, TP403, TP409, TP444, TP439, TP446, etc. 

Duplex/Super Duplex Stainless Steel Grade:
S31803, S32304, S31500, S32550, S32750, S32760, etc. 
Corporate Culture:
We focus on Quality First, Quality Traceability, and Quality Stability!
We focus on Customer First, People First, and Quality-Oriented!
Success:
First factory started in 1997, in the name of Torich , now covers 50000 square meters of factory building, with more than 100employees, and over 45 million RBM assets.
In 2008, we started the company of Torich International Limited for international business and marketing.
Welcome partners from all over the world for long term cooperation!