4. Fields of application and the chromates to be expected
The following overview assigns typical fields of application to the insulation materials used there and to the chromates to be expected. What is decisive in each case is the combination of chromium-alloyed hot component, basic component, oxygen and temperature. E-glass, calcium silicate and AES wools such as Superwool contain above all calcium oxide; mineral wool contains calcium and sodium oxide. Sayano et al. identified CaCrO₄ on the calcium-containing insulation material and Na₂CrO₄ on the sodium-containing insulation material. [11]
| Field of application | Insulation or location (basic component) | Chromates to be expected | Question of use and waste |
|---|---|---|---|
| Gas and diesel engines, locomotive and marine engines | On and around the engine mostly E-glass and needled glass fibre mats (CaO), in the high-temperature range calcium silicate mats and Superwool (CaO); onward exhaust lines with mineral wool (CaO/Na₂O) as roll material; insulation pads and insulation mattresses made of glass fabric (CaO) and mineral wool (CaO/Na₂O) | On and around the engine above all calcium chromate; on inlet and outlet lines calcium and/or sodium chromate | During maintenance work, the REACH question of use for sodium chromate already arises today where removed mineral wool products are reused; under the planned ECHA restriction in its present form, irrespective of the individual chromate |
| Gas and steam turbines | In very hot areas calcium silicate products with a high calcium content; the insulation mattresses that follow often made of E-glass and mineral wool products | Calcium and/or sodium chromate | as for engines |
| Biogas plants, combined heat and power plants and cogeneration plants | as for engines and turbines | as for engines and turbines | as for engines |
| Food processing, greenhouses and plantations with combined heat and power plants | as for combined heat and power plants | as for combined heat and power plants | as for engines |
| Data centres, emergency power generating sets, decentralised energy supply of public buildings and hospitals | as for combined heat and power plants, cogeneration plants and turbines | as for combined heat and power plants, cogeneration plants and turbines | as for engines |
| Vehicles, construction machinery, exhaust gas aftertreatment | Heat shields, for instance at the turbocharger, with felts and mats containing mainly calcium oxide, in part calcium silicate assemblies; external insulation on DPF and SCR; clipped double walls of hot components, open to oxygen, with insulation materials on the inside (E-glass, calcium silicate) | above all calcium chromate | as for engines |
| Waste incineration | Furnace during overhauls, door area, floor area of the furnace accesses and the surroundings of the furnaces through dust being stirred up (residues, no insulation) | The individual chromates are not decisive here | Waste and cleaning; a question of use arises at most where ashes are further used as a constituent of other products, provided they are not disposed of |
Risk assessment to be drawn more widely
For biogas plants with attached agriculture, the risk assessment is to be drawn more widely: the spreading of contamination into operating areas and foodstuffs and the environmental burden are to be included.
In food processing, in greenhouses and on plantations, high air humidity from irrigation or steaming can promote the formation and the gas phase transport at the hot components. The German statutory accident insurance institution BG ETEM names air humidity and, from approximately 550 °C, water vapour as influencing factors; Tatar works with heavily humidified air (section 14). [2, 35]
Because of their high energy demand, data centres are increasingly equipped with their own energy supply from gas engines or gas turbines. Engine manufacturers attribute the growing demand for quickly available own supply to the limited grid capacity. These plants are insulated in the same way as combined heat and power and cogeneration plants. [74]
Emergency power generating sets and the decentralised energy supply with combined heat and power and cogeneration technology in public buildings and hospitals correspond to the same constellation. In hospitals, spreading of contamination affects areas with vulnerable groups.
A particular feature in the Netherlands: heating installations are frequently fitted with textile insulation made of E-glass or mineral wool. What is decisive there are the hot components such as the combustion chamber and the flue gas path, at which the temperatures required for chromate formation are reached.
Sources cited in this section
- 2.BG ETEM: Mögliche Chrom(VI)-Exposition, last amended 3 August 2026.
- 11.Sayano, A.; Kanno, H.; Inagaki, S.; Takahashi, M.; Yoshida, M.: The formation of Cr(VI) compound at the interface between metal and heat-insulating material and the approach to prevent the formation by sol-gel process. Journal of the Ceramic Society of Japan 2015, 123, 677-684. DOI: 10.2109/jcersj2.123.677. Submitted study
- 35.Tatar, G. et al. / Gannon, P.: XPS Characterization of Aluminosilicate Fibers Post Interaction with Chromium Oxyhydroxide at 100-230°C. Journal of The Electrochemical Society 165 (2018), C624-C632. DOI: 10.1149/2.0801810jes. Submitted full text.
- 74.Latitude Media: Wärtsilä to supply 282 MW onsite power solution for a U.S. data center as AI growth intensifies demand for reliable power, 5 October 2026; 15 Wärtsilä 50SG gas engines, justified by limited grid capacity. Accessed 8 October 2026.