Three Pass Fire Tube Wet Back
Steam Boiler

Boiler with three-pass wet back fire tube
From a capacity of 500 to 50,000 kilograms per hour.
Up to a working pressure of 30 bar.
Design with Carogate Furnace and Spiral Pipe
Intelligent control and safety system with modular capacity performance.

Consumables and Equipment

High-quality European standard materials are used in the construction of boilers to increase the lifespan of the device.

Engineering & Designing

Designing state-of-the-art products is accomplished through modern technical knowledge and fluid and solid analysis.

Manufacturing and Production

Equipment production is carried out using the latest manufacturing equipment such as Four-Gun Roll Coaters, automatic Submerged Arc Welding machines for both powder and flux, Firetube Expander Rollers, and more.

After Sales Service

24-hour after-sales services are available in all cities of Iran to launch and ensure customer satisfaction.

Cross-sectional view
Completion facade

The structure of Packman's three-pass fire tube steam boilers

The design of firetube steam boilers by Packman Company is based on the European standard BS/EN 12953, of the “Shell Type Steel with Welded Structure” type and the “Three Pass, Wet Back, with Internal Reversal Chamber” design.
According to this plan, the hot gases created by the burner enter the first pass tube bundle after passing through the furnace and the return chamber (first pass), and after passing through them and reaching the front smoke chamber, they enter the second pass tube bundle (second pass) and after traveling the path and reaching the rear smoke chamber, they exit from the chimney..
Therefore, heat exchange between hot gases and water inside the device occurs through three parallel paths, hence this design is called “Three Pass”. Additionally, since one side of all major pressurized components of the machine is constantly in contact with water, the term “Wet Back” has been added to the name of this design to distinguish it from other types.
The sheets used in the construction of all pressure parts of Packman steam boilers are all of the type of heat-resistant carbon steel sheets with specifications in accordance with the mentioned reference standard, which is sheet 17Mn4 according to DIN 17155 standard.
The steel pipes (heat transfer tubes) used in the construction of steam boilers by Packman Company are seamless heat-resistant pipes with specifications compliant with the mentioned standard. Primarily, they consist of pipes such as St35.8 according to DIN 17175 standard. Their import is exclusively handled by Pakman Company from European countries..

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To connect pipes to the network, an Orbital Welder device is used. This device can establish the connection accurately and without creating welding-related impurities, ensuring a proper connection.

Welding tube machine

Some of the manufacturing and design features of Packman steam boilers include:

85%More heat transfer
spiral tube

Spiral tubing improves smoke circulation in the third pass of boiler tubes, ensuring turbulent flow is maintained in the boiler and increasing heat transfer by up to 85 percent on an equal heat exchange surface.

Spiral Welded Pipe

In the welding of connections for various parts of steam boilers, Packman Company employs five welding methods or processes, including: Submerged Arc Welding (SAW) Flux-cored arc welding (FCAW) Shielded Metal Arc Welding (SMAW), Welding by the method of metal active gas (MAG) shielded arc welding. Welding by the method of covered electrode under inert gas shielding (MIG or TIG).

Welding of different sections.

Frequently Asked Questions

Some frequently asked questions have been set up for your convenience in selecting and obtaining further information. If you have further questions, please contact the technical department of the company.


Yes, due to the boiler’s need for preheating water and preventing oxygen corrosion, a deaerator is required. Additionally, for draining the boiler water and other equipment, a blowdown is needed..

Please note that to determine the capacity of your burner, you need the boiler output capacity, the combustion efficiency of the package, and the correction factor for the elevation above sea level at the installation site.. Keep in mind that “burner efficiency” or “boiler efficiency” on their own do not have any meaningful interpretation, and the manufacturer must specify the efficiency of the package based on the particular combustion system performance test..

Due to gas pipeline pressure, attention must be paid to the capacity and the declared number by the burner seller. In some capacities, gas pressure is low (less than 5 pounds per square inch), while in others, it requires pressure higher than this figure.

The recommended height limit for the steam boiler chimney is 6 meters, but it can be higher depending on factors such as capacity, diameter, friction rate of the chimney material, volume of combustion products, barometric pressure at the installation site, momentary pressure of combustion products exiting the nozzle, and fluid velocity. For detailed information, please contact the technical department of Pakman Company..

To obtain the catalog for Packman Company's three-pass steam boiler, click here.

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