Double-H Finned Tubes for Boilers – ASTM A179 Steel

Product Overview

Double-H finned tubes, also known as Double H-type fin tubes, are high-efficiency heat-transfer components widely used in boiler economizers, waste-heat boilers, industrial heating systems, and other flue-gas heat recovery equipment.

Our Double-H finned tubes are manufactured using ASTM A179 seamless cold-drawn low-carbon steel tubes as the base tube. The H-shaped fin configuration increases the external heat-transfer surface while maintaining good gas-side flow characteristics. Compared with plain tubes, the Double-H design can improve heat exchange efficiency and help reduce the overall size of boiler heat-transfer sections.

ASTM A179 is specified for seamless cold-drawn low-carbon steel tubes used in heat exchangers, condensers, and similar heat-transfer equipment. The standard covers outside diameters from 1/8 in. to 3 in. (3.2–76.2 mm).

With careful material selection, controlled fin welding, dimensional inspection, and comprehensive quality testing, our Double-H finned tubes are engineered for reliable performance in demanding boiler environments.

• High heat-transfer efficiency: The Double-H fin structure provides an increased external heat-transfer area for effective heat recovery.

• Excellent welding quality: Fins are securely joined to the ASTM A179 base tube using controlled manufacturing processes.

• Reduced ash accumulation: The H-type fin arrangement provides relatively open gas passages, supporting cleaner operation in flue-gas applications.

• Reliable mechanical performance: ASTM A179 low-carbon steel offers good formability and suitability for heat-transfer tube applications.

• Customizable dimensions: Tube diameter, wall thickness, fin height, fin thickness, fin spacing, and tube length can be manufactured according to project requirements.

• Suitable for boiler retrofits and new equipment: Double-H finned tubes can be supplied for replacement economizer elements or newly designed boiler systems.

Double-H finned tubes are commonly used in:

• Boiler economizers

• Industrial and utility boilers

• Waste-heat recovery boilers

• Biomass and coal-fired boiler systems

• Flue-gas heat recovery units

• Air and gas preheating equipment

• Industrial furnace heat-recovery systems

They are particularly suitable for applications where efficient heat recovery from hot flue gas is required while maintaining a robust and compact heat-transfer surface.

The base tube is manufactured from ASTM A179 low-carbon steel, a seamless cold-drawn tube material designed for heat-transfer equipment. ASTM A179 requires the tubes to be produced by the seamless process and cold drawn; the standard also specifies post-cold-drawing heat treatment requirements.

The controlled low-carbon composition supports good processing and welding characteristics for heat-transfer tube manufacturing.

Typical specified minimum or maximum properties include:

*Elongation requirements may depend on the applicable specification conditions and tube dimensions. Mechanical requirements should be confirmed against the applicable edition of the standard and the purchase specification.

Double-H finned tubes can be supplied in a wide range of dimensions according to boiler design and operating requirements.

• Outside diameter: Commonly 25.4 mm to 63.5 mm

• Common boiler tube sizes: 25.4 mm, 31.75 mm, 38.1 mm, 44.5 mm, 50.8 mm and 57 mm

• Wall thickness: Typically 1.5 mm to 6 mm

• Tube length: Custom manufactured according to economizer or boiler assembly requirements

ASTM A179 itself covers seamless tubes from 3.2 mm to 76.2 mm outside diameter, while the practical size selected for a Double-H finned tube depends on the boiler design, pressure conditions, heat load, and fabrication requirements.

• Fin thickness: Customizable according to service conditions

• Fin height: Designed to meet required heat-transfer performance

• Fin pitch: Optimized according to gas flow, fouling conditions, and thermal design

• Fin material: Carbon steel or another specified material compatible with the operating environment

Custom sizes and non-standard configurations are available upon request.

Our Double-H finned tubes are produced through a controlled manufacturing process designed to achieve reliable bonding and dimensional consistency:

1. Raw material inspection – ASTM A179 tubes are checked for material conformity and surface condition.

2. Tube preparation – Tubes are cut, cleaned, and prepared for fin assembly.

3. Fin fabrication – H-type fin components are formed to the specified dimensions.

4. Fin welding – Fins are attached to the base tube using a controlled welding process.

5. Dimensional control – Tube straightness, fin spacing, fin height, and overall dimensions are inspected.

6. Weld quality inspection – Welded areas are examined according to applicable quality requirements.

7. Final inspection and protection – Finished tubes undergo final quality checks before packing and shipment.

Quality control is an essential part of Double-H finned tube production. Depending on the project specification, inspection and testing may include:

• Material certificate review

• Chemical composition verification

• Dimensional inspection

• Surface quality inspection

ASTM A179 includes mechanical and quality tests such as hardness, flattening, flaring, and hydrostatic testing, with nondestructive electric testing available as an alternative when specified by the purchaser.

• Visual inspection of fin surfaces and weld areas

• Outside diameter and wall-thickness measurement

• Fin height and thickness measurement

• Fin pitch inspection

• Tube length and straightness measurement

• Weld integrity inspection

• Nondestructive testing, where required

• Hydrostatic or pressure testing, when specified

• Final packing and marking inspection

Additional third-party inspection can be arranged according to customer or project requirements.

With a focus on industrial heat-transfer applications, we supply Double-H finned tubes designed to meet the practical requirements of boiler manufacturers, engineering contractors, and maintenance companies.

Our advantages include:

• ASTM A179 seamless steel base tubes

• Custom dimensions and fin configurations

• Controlled welding and manufacturing procedures

• Comprehensive inspection options

• Support for OEM, replacement, and project orders

• Export-oriented packing and documentation

• Technical communication throughout the quotation and production process

Whether you require Double-H finned tubes for a new boiler economizer or replacement heat-transfer elements for an existing system, we can provide a customized solution based on your drawings, operating conditions, and technical specifications.

To receive an accurate quotation, please provide the following information where available:

• Base tube standard and material

• Tube outside diameter and wall thickness

• Tube length

• Fin thickness and height

• Fin spacing or pitch

• Required quantity

• Operating temperature and pressure

• Applicable inspection requirements

• Drawings or technical specifications