Heatmasters Service Combo: Pre-Heating and PWHT Of Boiler Drums


On-site pre-heating of boiler drum studs utilizing Heatmasters heat treatment equipment.

Last month, we wrote about our cooperation with ENITEC Sp. z o.o. (Grupa ENERGOINSTAL S.A.), manufacturer of boiler components and pressure vessels for the energy industry at the highest quality levels. Heatmasters provided a service combo for Enitec, which included pre-heating and PWHT (post-weld heat treatment) of a boiler drum. These service combos are a part of our integrated service model which provides our customers with multiple benefits arising from complete solutions.

“Despite the challenges of this job, such as large dimensions and weight, the materials involved, the requirements of standards and regulations, thanks to the expert advice provided by Heatmasters and professionalism in pre-heating and post-weld heat treatment, the task was completed successfully.”

– Michał Krawiec, Project Engineer at Enitec Sp. z o.o

On-Site Pre-Heating

Heatmasters’ wizards of metal with decades of heat treatment experience were on-site at Enitec’s facilities in Poręba, southern Poland, providing accurate pre-heating during the supervised process, which in addition to heat treatment involved welding and dehydrogenation.

Pre-heating metals is an additional, but often crucial step in welding applications. Pre-heating metal before welding decreases the temperature difference between the welding arc and the material being worked on. It ensures the rate of cooling in a finished weld is slower, lowers the chance of cracking, and allows hydrogen to diffuse out. It also ensures that any moisture or contaminants on the surface of the part are removed, which could otherwise allow the introduction of hydrogen during the welding process.

There are many factors to consider when preheating in welding is required such as welding code or standard requirements, prior cracking issues, component section thickness, base metal chemistry, ambient temperature, and filler metal hydrogen content. Most often, welding codes or standards will specify the minimum preheat temperature based on the welding process and component material/thickness.

During the pre-heating works, our team used two Heatmasters HM406 pre-heating units. These units had a combined power output of 80 kW and 12 heating channels.

We also utilized our VHY-Stud Heater elements, designed for the pre-and post-weld heating of studs and outlet tubes. The form of the VHY-stud heater enables fixing the heater near the weld.

The pre-heating works went well, and we were glad to be working together with fellow professionals at Enitec’s facilities. The project, however, was far from over as boiler drums would also receive post-weld heat treatment after works at Enitec’s facilities were completed.


The boiler drum, weighing 38 tons, was transported to our modern heat treatment facility in Będzin, Poland which is equipped with several fixed heat treatment furnaces. The journey was only around 30km which meant transporting the boiler drum was a feasible and cost-effective solution. In other cases, in which transport would not have been feasible, Heatmasters can provide a temporary furnace solution at the customers’ premises.

The boiler drum was loaded into a furnace with dimensions of 16 x 4 x 4 meters and a maximum temperature of 950°C. The heating process took around 40 hours per drum, during which the heating parameters were controlled and documented using the Heatmasters Rigel26 digital temperature control system. This system ensures that each heating process is performed accurately, according to the customers’ requirements and fabrication codes.

The electrical heat treatment furnace and boiler drum almost ready for heating.

The heating process takes around 40 hours per drum.

Boiler drums are loaded and unloaded using 2 cranes.

Once the heating process was completed, cooling to ambient temperatures took another 18 hours. After this, the boiler drum was transported back to Enitec along with digital heat treatment certificates and other required documentation.

Integrated Service Model

When our customers choose multiple services or complete service solutions, we can manage a selected part of the delivery process. This service model allows for an optimized process, saving time and effort, whilst our customers have fewer moving parts to take care of and fewer jobs to juggle. During this project, we provided the customer with pre-heating and PWHT according to the highest quality and code standards. Additional services such as transportation, NDT, and surface treatment services were also available for the customer.

”We appreciate Heatmasters’ experience in steel heat treatment and recommend them as a proven partner.”

-Krystian Kowal, Vice President at Enitec Sp. z o.o.

Heatmasters team enjoyed this cooperative project and we are already looking forward to future challenges utilizing our knowledge and long-term experience in high-quality heat treatment and industrial services. Our cooperation with Enitec continues with the processing of several additional boiler drums.

The boiler drum back at Enitec’s facilities, one of their key products.

In addition to heat treatment of workpieces in fixed furnaces, Heatmasters provides custom-tailored solutions including:

  • On-site pre-heating and post weld heat treatment (PWHT)
  • Heat treatment of large workpieces in portable temporary furnaces
  • Refractory dry-outs
  • Wide range of industrial services (NDT, surface treatment, welding, etc.)
  • High-tech heat treatment equipment (furnaces, transformers, temperature control systems etc.)
  • Modernizations for all manufacturer’s heat treatment equipment

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