Heat Treatment

Expertise, precision, and state-of-the-art technology – for optimal heat treatment results.
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GGT Glühtechnik Service GmbH – Your partner for heat treatment

Our experienced specialists carry out all preheating and PWHT operations with the highest precision and reliability. We rely on innovative processes and consistently adhere to the highest quality standards. This makes us the ideal partner for diverse applications across a wide range of industries

Hubschiff in Bremerhaven
Shipyard industry - Oil Rig under construction in Gdansk, Poland.

Shipbuilding industry (ships) & offshore technology (drilling rigs)

Ship engines, propellers and offshore technology (platform foundations, drill strings and connecting elements).

Petrochemical Industry

Chemical plants such as reactors, heat exchangers and sour water and sour gas pipelines.

Rohrleitungsbau
heat exchanger at an oil refinery, large size, daylight. Deep processing of oil
Industrial heat exchanger or boiler tubes bundle. Two way heat exchanger shell and tubes opened for repairing and deposits cleaning at petrochemical enterprises industrial background with copyspace.
Assembly of a steam turbine rotor in a plant workshop. Power equipment manufacture with processing line.
supraleitende-Spulen-für-Fusionsreaktoren
3d render of a conceptual stellarator with partial cutout revealing fusion plasma process

Energy industry (power plants)

We treat Turbine rotors, turbine casings, high-pressure, medium-pressure, low- pressure pipes and other energy-generating systems to maximize their service life and increase efficiency.

Pipeline construction (pipe joints and tanks)

Our methods eliminate stresses in pipelines and joints, thus increasing material durability.
Male worker inspection at steel long pipes and pipe elbow in station oil factory during refinery valve of visual check record pipeline tank oil and gas
Heavy Machinery and Gas Pipeline Construction Site. Pipes are Laid on Top of Supportive Sandbags Beside Trench and Welded Together.
Heavy Machinery and Gas Pipeline Construction Site. Pipes are Laid on Top of Supportive Sandbags Beside Trench and Welded Together.
Crankshaft for a large engine is fixed in the machine for manufacturing, processing or servicing. Industrial concept. Metalworking concept
automotive crankshaft. Isolated on white background

Steel and plant engineering (gears)

We offer customized heat treatment processes to optimally adapt to the specific requirements of large-scale industrial projects.

Our Processes at a Glance

To meet a wide range of requirements, we offer a variety of heat treatment processes, including:

Refining: Hardening, tempering:

Hardening, tempering, and quenching are heat treatment processes that selectively improve the mechanical properties of steel. In hardening, the steel is heated to high temperatures and then rapidly cooled, making it extremely hard but also brittle. To reduce brittleness, tempering follows, in which the hardened steel is heated to a lower temperature and slowly cooled to increase toughness. Quenching and quenching combine hardening and tempering to achieve an optimal balance of strength and toughness.

Preheating
Welding generates high stresses in the materials, which, if cooling is too rapid, can lead to hardening and cracking. Targeted preheating significantly reduces the cooling rate. This gives the material sufficient time to relieve stresses and distribute the carbon evenly throughout its structure. The result: a more homogeneous material structure and significantly improved weld quality.

During welding, small amounts of hydrogen can become trapped in the material – especially in the weld area. These hydrogen accumulations significantly increase the risk of cold cracking or other cracking issues.

Hydrogen degassing, also known as effusion annealing or "soaking," involves heating the weld area to a temperature approximately 100 to 150°C above the preheating temperature immediately after welding. This temperature is then maintained for at least 3 to 6 hours.

The goal of this process is to drive the trapped hydrogen out of the material, thereby significantly reducing the risk of hydrogen-induced cracking.

The result: a stable, stress-free weld joint with consistently high material quality.

When components are used in sour gas-containing media – especially in contact with hydrogen sulfide (H₂S) – the highest demands are placed on material quality. Even small amounts of embedded sulfur can impair the material's durability and lead to embrittlement or cracking. Through controlled PWHT, also referred to as "soaking" in this context, the weld area is heated to a temperature of 100 to 150°C above the preheating temperature and held for at least two hours. This controlled heat input allows sulfur trapped in the pores to be driven out of the microstructure, thus optimally preparing the material for subsequent sour gas operation. The result: maximum safety and resistance, even under the most demanding operating conditions.

Welding, forming, or machining processes create internal stresses in the material, which can impair the dimensional accuracy and long-term performance of the component.

Controlled stress-relief annealing selectively reduces these shrinkage and welding residual stresses without significantly altering the material's mechanical or chemical properties.

or tempered steels, a temperature is selected that is no more than 30°C below the tempering temperature to reliably preserve the microstructure.

The result: stress-free workpieces with high dimensional accuracy and improved structural stability – ideal for subsequent machining operations or use under load.

Tempering is a proven PWHT process for the targeted post-treatment of welded materials. The aim is to relieve the residual stresses generated during welding within the component and simultaneously reduce the hardness in the heat-affected zone (HAZ) through controlled microstructural transformations.

The result: a stress-free, tough, and uniformly structured material – optimally prepared for further use or processing.

We are of course also available for other PWHT processes, such as:

  • Diffusion PWHT
  • Stabilization PWHT
  • Soft PWHT
  • Solution PWHT (stainless steels, duplex steels)
  • Pearlite PWHT (cast iron)
  • Ferrite PWHT (cast iron)
  • Recrystallization PWHT (after cold forming)

Specialized Applications

Our special processes, including drying and heat treatment operations with high-performance HV gas burners, are tailored to particularly demanding applications.

Heat treatment plants and assembly supervision

In addition, we develop and manufacture heat treatment plants tailored to your needs and ensure thorough assembly supervision.

Gallery

Our team will guide you through the entire process from
planning to successful implementation.

Call us or send us a message.

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