2023 Heat Treatment Services at the Montes del Plata Pulp Mill in Uruguay


Montes del Plata Pulp Mill Heatmasters Heat Treatment Services Annual Maintenance Shutdown 2023

During Q1 2023, Heatmasters heat treatment experts were once again in Uruguay, during the annual maintenance shutdown of the Montes del Plata Mill, officially called “PGP 2023” (Parada General de Planta). Over 3,000 people worked simultaneously during the maintenance shutdown to complete maintenance, improvement and inspection works at the plant. Heatmasters heat treatment experts were excited to be a part of this project, providing heat treatment services on-site and working with ANDRITZ Uruguay specialists.

The annual maintenance shutdown ensures the plant meets its’ goals related to pulp and energy production, environmental safety, quality, and sustainability as well as the health and safety of people, which is the number one priority for the plant.

On-site Heat Treatment at the Montes del Plata Mill in Uruguay - Heatmasters - Local zone heat treatment - “PGP 2023 (Parada General de Planta)”.

Scope of Heat Treatment Works

During the annual maintenance works bends and tubes in the superheaters II, III and IV of the recovery boiler were to be replaced. The repair of high-grade materials used in superheaters often requires special welding techniques and heat treatment. During this project, annealing was required.

Annealing is a controlled heating and cooling process used to alter the microstructure of a metal or alloy, providing desirable properties such as stress relief, softening, improved ductility, refined grain structure, and homogenization of alloying elements.

Return bends and tubes were heated by our heat treatment experts during their replacement. In total, around 80 welds were heat treated during this project, with each heating process digitally documented thanks to Heatmasters’ modern heat treatment equipment and integrated temperature control systems.

On-site Heat Treatment at the Montes del Plata Pulp Mill

Heat Treatment Equipment

Heatmasters’ heat treatment specialists were equipped with multiple HM406T_R26 heat treatment units which have a power output of 40kW and 6 heating channels. These fully automatic thyristor-controlled heat treatment units for the annealing of metal parts have been designed with usability in mind: their simple and lightweight structure allows effortless mobility and efficient heat treatment work at any location.

During the previous projects at the Montes del Plata Mill, our team received positive feedback regarding the equipment’s compact design, which allowed the units to stay in place on the narrow hallways of the plant without causing any issues and reducing time spent moving equipment during the works.

Heatmasters HM406T_R26 mobile heat treatment equipment at the Montes del Plata Mill in Uruguay

The units’ computerized state-of-the-art temperature control system provides digital, easy, and accurate setting, controlling, monitoring, and digital documentation of the heat treatment process, even remotely. This allowed our team to provide the customer with heat treatment certificates of each process in PDF format. Thanks to the digital control system, an external temperature recorder is also not required. Heatmasters heat treatment units are almost maintenance-free, ensuring cost-efficient and trouble-free heating operations, which is why they come with a 3-year warranty.


Montes del Plata Mill

The Montes del Plata Mill is a eucalyptus wood pulp mill located in Southern Uruguay. It is run as a joint venture between Stora Enso and Arauco. Montes del Plata produces 1,400,000 tons per year of bleached eucalyptus pulp, which is exported to North America, Europe and Asia. For eight years the industrial plant has been operating in Punta Pereira, Conchillas, in a high-tech industrial complex that in turn generates renewable electricity.

The Montes del Plata Industrial Complex is environmentally friendly, incorporating the latest technological advancements which guarantee minimal environmental impact, meeting all environmental regulations established by the European Union (IPCC), and operating according to the industry’s best available techniques (IPPC-BAT).

Montes del Plata owns 190 000 hectares of land and leases 56 500 hectares of land, and the company has incorporated standards of responsible forest management – FSC® and internationally recognized PEFCTM-, which certify 100% of its plantations. Montes del Plata is also the largest private power generator in Uruguay, the third-largest producer after the hydroelectric stations of Salto Grande and Palmar. The mill delivers its surplus energy of around 500 GWh per year to Uruguay’s national grid, which equates to around 5% of the country’s total energy needs and is a contributor to the country’s conversion of its energy matrix to renewables, minimizing fossil fuel use.

Pulp Production Process

From the production of seedlings in its own nursery to the export of cellulose, Montes del Plata involves more than 6,000 people throughout its production chain. Find a short summary of the pulp production process below.

Wood Chipping

Wood is transported to the industrial complex on trucks and barges, after which it is converted into smaller pieces called chips to reduce and standardize their size whilst facilitating the digestion process.


The chips enter the digester. A mixture of water and chemicals called white liquor is added to the chips, causing cellulose fibres to separate from lignin, a high-energy wood component, at high pressure and temperature.


The pulp from the cooking process is filtered, washed, and then bleached. This changes the color of the pulp from brown to white.


White sheets pass through dryers until the water content is less than 10%. After this, they are cut, grouped into bales, and packaged.

Chemicals and wood components from this process are concentrated and burned, generating steam and electricity. Non-combustible components are reintegrated into the pulp production process. The plant’s energy and chemical inputs are recovered and reused, making the Kraft process economically and environmentally viable. Atmospheric emissions are 99% water vapor and meet the most demanding national and international environmental standards, just as liquid effluents do.

Pulp Mill Superheater Heat Treatment

Heat Treatment Services

Heatmasters looks forward to future heat treatment projects utilizing our knowledge and long-term experience in high-quality heat treatment and industrial services.
In addition to on-site pre-heating and post-weld heat treatment (PWHT), Heatmasters provides custom-tailored solutions including:

  • Heat treatment of workpieces in fixed furnaces
  • 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


Click here to read more about Montes del Plata.
Click here to read more about Stora Enso.

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