H/HH Type High-Frequency Welded Fin Tubes for Heat Exchangers

H/HH type high-frequency welded finned tubes are rectangular (H-shaped) or double-rectangular (HH) plate-finned tubes used as compact, high-efficiency heat-transfer elements in economizers, air preheaters and other gas-to-fluid heat exchangers. Two steel plates are resistance-welded to opposite sides of a round base tube, forming an “H” cross-section that greatly increases external surface area while creating straight flue-gas channels with low pressure drop and good soot-blowing accessibility.

Specifications

• Base tube OD: 25–63 mm (other diameters on request)

• Base tube wall thickness: ≥ 3.0 mm for boiler service

• Maximum length: up to about 18 m per tube (depends on grade and handling limits)

• Fin height: up to approx. 200 mm

• Fin thickness: 1.5–3.5 mm

• Fin spacing (pitch): typically 8–30 mm

• Base tube materials: carbon steel, low-alloy steel, Cr-Mo alloy steel, austenitic stainless steel

• Fin materials: carbon steel, low-alloy steel or stainless steel to match service conditions

Key Advantages

1. High thermal efficiency in a compact bundle
   The rectangular H/HH plate fins provide several times the heating surface of a plain tube economizer of the same diameter and length, enabling much smaller, lighter heat-exchanger banks.

2. Low wear, low fouling in dusty flue gas
   H-type fin tubes are widely used for coal-fired units, CFB boilers and waste-incinerator economizers because the straight channels and expanded gas-flow area help reduce gas velocity, erosion and ash deposition compared with smooth or spiral-finned tubes.

3. Robust high-frequency welded fin-to-tube bond
   Automatic high-frequency resistance welding produces a continuous metallurgical bond along the fin edge with minimal heat-affected zone, giving high tensile strength at the joint and excellent resistance to vibration, thermal cycling and soot-blowing.

Chemical Composition

Values are ladle analysis limits from the respective standards; actual mill test results are typically within these ranges.

Mechanical Properties

Applicable Standards

Base tubes for H/HH finned tubes are typically produced to:

• ASTM / ASME: A179, A192, A210, A213 series for boiler and heat-exchanger tubes

• EN: EN 10216-2 grades such as P235GH, P265GH for pressure service at elevated temperature

• GB: GB/T 5310 high-pressure boiler tubes (e.g., 20G)

• JIS / GOST: Equivalent boiler and pressure-tube grades as required by project specifications

Typical Applications

• Power and industrial boilers: economizers, low-temperature economizers, air preheaters, waste-heat boilers

• Waste-heat recovery: tail-flue gas coolers on coal-fired, oil-fired and waste-incineration units, CFB boilers and process furnaces

• Process and marine sectors: fired-heater convection sections, process-gas coolers and marine exhaust-gas economizers using dust-laden, high-temperature gases

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.

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