39. Appendix: insulation materials with basic oxides and where they are installed
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The following commercially available insulation materials contain the basic oxides described, which can trigger thermochemical in-situ formation of the chromium(VI) compounds described. These are not assumptions, but conclusions drawn from manufacturer information, warning notices from users and my own field observations.
The evidence column names the origin of the information. H stands for information from a manufacturer or from a standard, W for a warning notice or a user report, F for my own field observation. Where a manufacturer publishes no figures, this is stated expressly in the table.
The content figures refer to the oxide analysis of the insulation material in the as-delivered condition. Whether and to what extent the oxides become available at the interface is dealt with in Sections 9 to 12 of this analysis.
Insulation materials containing calcium, sodium and other basic oxides
| Material and trade form | Documented content of basic oxides | Evidence |
|---|---|---|
| E-glass, yarn and fabric for printed circuit boards and aviation | CaO 16 to 25 %, MgO 0 to 5 %, Na₂O and K₂O 0 to 2 % | H [167] |
| E-glass, general applications: fabric, tape, needled mat, roving | CaO and MgO together 16 to 30 %, alkali metal oxides 0 to 2 % | H [167] |
| E-glass, manufacturer information on textile fibres and fabrics | CaO 16 to 25 %, Na₂O and K₂O 0 to 1 %, MgO 0 to 5 % | H [168] |
| ECR glass, boron-free modification of E-glass | no oxide table of its own published; the standard defines ECR only as a boron-free modification of E-glass | H [167] |
| Mineral wool, rock and glass wool: mat, wire mesh mat, board, pipe section | Na₂O, K₂O, CaO, MgO and BaO together more than 18 per cent by weight; the value is part of the substance identity under Annex VI index 650‑016‑00‑2 and not a batch property | H [169] |
| AES wool, substance definition of the manufacturers | calcium oxide and magnesium oxide together 18 to 43 %, silicon dioxide 50 to 82 % | H [170] |
| AES wool, blanket (Superwool Plus Blanket) | CaO 26 to 32 %, MgO 3 to 7 % | H [170] |
| AES wool, board (Superwool Plus Board) | CaO and MgO together 31 % | H [170] |
| AES wool, blanket (Insulfrax LT) | CaO 27 to 33 %, MgO 2.5 to 6.5 % | H [171] |
| AES wool, blanket (Insulfrax 1300 HT) | CaO and MgO together 21 to 27 % | H [171] |
| AES wool, magnesium silicate variant (Isofrax) | MgO 18 to 27 %, no declared CaO content | H [171] |
| Aluminium silicate wool and ceramic fibre (ASW, RCF): blanket, board, paper, module | Na₂O, K₂O, CaO, MgO and BaO together less than or equal to 18 per cent by weight; dividing value in relation to index 650‑016‑00‑2. The manufacturers' data sheets do not quantify alkali and alkaline earth oxides | H [173, 78, 172] |
| Calcium silicate, board and moulded part | CaO 38 to 43 % | H [174] |
| Calcium silicate, pipe section and block | synthetic calcium silicate at least 90 %; a breakdown into CaO and SiO₂ is not published | H [175] |
| Perlite, expanded: loose fill and moulded part | Na₂O 3.7 %, K₂O 5.3 %, CaO 0.5 %, MgO 0.1 %. The analysis comes from a filter perlite; for pipe and tank insulation materials the manufacturers publish no oxide analysis | H [176] |
| Vermiculite, expanded: loose fill and board | MgO 21.5 to 25.5 %, K₂O 3 to 6 %, CaO 2.0 to 6.0 %; the data sheet additionally lists Cr₂O₃ at 0.01 to 0.15 % | H [177] |
| Aerogel blanket | no calcium compound and no sodium compound declared; more than 50 % textile glass without chemical specification | H [178] |
| Silica and quartz glass fabric above 96 % SiO₂: fabric and needled mat | 96 to 99 % amorphous silica; the remaining 1 to 4 % is not broken down | H [179] |
| Basalt fibre, fabric and needled mat | no oxide breakdown published; the manufacturer names only a special oxide composition | H [180] |
| Ceramic fibre paper and ceramic fibre felt | binder 2 to 15 % organic or 50 to 70 % inorganic; the substance identity of the inorganic binder is not named | H [172] |
| Assembly paste for hot components, containing calcium | calcium hydroxide 10 to below 20 per cent by mass | H [181] |
Two rows call for a comment. The substance definition of mineral wool and that of ceramic fibre are delimited from each other by the same oxide content: more than 18 per cent by weight leads to mineral wool, up to and including 18 per cent by weight to ceramic fibre. The content of basic oxides is therefore not a secondary characteristic, but the characteristic that distinguishes the two substance groups. And the summation formula of Annex VI expressly names sodium, potassium, calcium, magnesium and barium oxide. [169, 173]
Applications using these insulation materials
| Field of application | Insulated components, insulation material and trade form | Temperature | Evidence |
|---|---|---|---|
| Yachts and superyachts | Exhaust line, exhaust manifold, dry turbocharger and indicator valves; insulation mat with riveted-on sheet metal cladding, metallic insulation cladding of cassette design, removable textile insulation shells. Removable sections are expressly provided for maintenance | surface below 220 °C required; components in the engine compartment up to 750 °C | H [182, 183] |
| Container ships and merchant ships, two-stroke engine | Exhaust manifold and exhaust lines; insulation with a cover of galvanised sheet metal | not stated in the document | H [184] |
| Container ships and merchant ships, four-stroke engine | Exhaust line from the turbocharger outlet via the exhaust gas boiler and the silencer to the funnel, plus the SCR unit; insulation pads on the turbocharger, continuous insulation from 30 mm thickness with cover sheet, SCR insulation designed to be demountable | turbine outlet 390 °C in normal operation, 450 °C in the design, 554 °C in emergency operation | H [184, 185] |
| Cruise ships | Auxiliary diesel engines, exhaust lines and exhaust gas cleaning; same engine series and same insulation design as in four-stroke operation in merchant shipping, removable mattresses on valves and fittings | as for the four-stroke engine | F |
| Locomotives and rail vehicles | Exhaust gas turbocharger, exhaust manifold, complete exhaust runs and exhaust gas aftertreatment; textile moulded insulation part to the fire protection standard EN 45545, integral insulation with an outer shell of stainless steel foil or thin sheet, stitched insulation mats with alkaline earth silicate, E-glass or silica as insulation material and stainless steel foil or nickel-base foil on the hot side, expressly removable and reusable | moulded part up to 650 °C; mat types up to 816 °C and up to 1,149 °C | H [183, 186] |
| Construction machines and mobile working machines | Turbocharger, manifold, exhaust system, particulate filter and SCR modules, underbody insulation and engine compartment heat protection; three-dimensional moulded fibre parts with outer shells of stainless steel foil or thin sheet | components up to 750 °C, surface reduced to below 220 °C | H [183] |
| Combined heat and power plants and cogeneration | Exhaust system and exhaust gas turbocharger of the gas engine; metallic insulation cladding as completely removable modules | exhaust gas 421 °C at full load, 476 °C at half load | H [187, 183] |
| Standby and emergency power installations, including in data centres | Exhaust line of the diesel generator set; calcium silicate or mineral wool pipe sections, laid in two layers, with jacket, banding and tie wire of stainless steel 304. For this case the manufacturer expressly recommends calcium silicate, because the organic binder of the mineral wool burns out from about 177 °C | 371 °C to almost 538 °C | H [188] |
| Gas and steam turbines | Exhaust duct, transition piece, turbine casing, heat recovery steam generator, silencer and stack; internal insulation behind liner sheets of 304 or 409 steel, flexible insulation pillows, fibre insulation mats and fibre modules in the heat recovery steam generator, insulation mattresses on the casing, removable and reusable | casing above 500 °C, exhaust duct above 480 °C, heat recovery steam generator up to 1,093 °C | H [189], W [190] |
| Road vehicles, trucks and passenger cars | Heat shields, cast manifolds, exhaust system, particulate filter, SCR and mounting mats in the catalytic converter; heat shield of cassette design with cover sheet or foil of stainless steel or aluminium and an insulation insert inside, needled mat as mounting mat | heat shield up to 1,100 °C depending on the material; peak manifold temperature 1,000 °C | H [191, 192, 193, 48] |
| Industrial furnaces, boilers, waste incineration and biomass plants | Boiler walls, flue gas ducts and pipework; rock wool wire mesh mats with galvanised or stainless steel wire mesh | up to 640 °C, heavy version up to 649 °C | H [194] |
| Chemical plants and refineries | Pipework on austenitic steels, valves and flanges; wire mesh mats, pipe sections and removable covers | up to 640 °C, pipe sections up to 650 °C | H [194] |
The materials side is quantified in the same documents. Under the European materials standard, stainless steel begins at 10.5 per cent chromium. For manifolds, pipes, catalytic converters and silencer housings, one manufacturer names the ferritic material 1.4509 with 17.80 per cent chromium and oxidation resistance up to 950 °C as well as 1.4521 with 19 per cent chromium up to 1,025 °C; the same manufacturer states the peak temperature at the manifold as 1,000 °C. In the exhaust duct of the gas turbine, the liner sheets are of 304 or 409 steel and the fastening of 304. On the exhaust line of the emergency generator set, the jacket, the banding and the tie wire are of 304. [193, 190, 188]
Both sides of the reaction described in Section 9 are thus present next to each other in the same components: the chromium-alloyed steel as the chromium source and the insulation material as the carrier of the basic oxides. The tables say nothing about the extent to which the reaction proceeds in an individual case. They say where the conditions for it are present.
Sources cited in this section
- 48.Morgan Advanced Materials / Thermal Ceramics: Superwool Plus Heat Shield, Product Data Sheet, 09/2019, three pages. In particular pages 1-2: automotive application, oxide composition, hot surface temperatures and presentation of fibre safety; page 3: European availability table.
- 78.European Chemicals Agency ECHA: Registration dossier Refractories, fibers, aluminosilicate, CAS number 142844-00-6.Available to the author, not publicly retrievable.
- 167.ASTM International: ASTM D578/D578M-18, Standard Specification for Glass Fiber Strands; version approved 1 July 2018, published August 2018, DOI 10.1520/D0578-18. Sections 4.1 to 4.4 with the composition tables 4.2.1 and 4.2.2 as well as the definition of E-CR glass in 4.2.4; evaluated from the publicly available four-page preview. Accessed 17 October 2026.
- 168.Insulcon B.V., Insulcon GmbH and Keramab N.V.: Material Safety Datasheet, E-Glass Fibre Textiles, form MSDS, valid from 3 April 2014, replaces the version of 27 April 2011; section 3. Accessed 17 October 2026.
- 169.Deutsche Rockwool GmbH & Co. KG, Gladbeck: Produkt- und Verwendungsinformation Steinwolle mit hohem Aluminiumoxid- und niedrigem Silikatanteil, 30 May 2017, notes I and II and section 3; and Knauf Insulation: Safety Data Sheet Rock Mineral Wool with ECOSE Technology, KI_DP_201, Revision 6.0 of 1 September 2023, sections 3 and 16. Both reproduce the substance definition of Annex VI index 650-016-00-2. Accessed 17 October 2026.
- 170.Morgan Advanced Materials, U.K. Thermal Ceramics Limited: Safety Data Sheet 448, Superwool HT NexGen Castingtip, revision 1 June 2025, and Safety Data Sheet 204, Aluboard 607 and others, revision 30 April 2024, in each case section 3 with the substance definition of alkaline earth silicate wool; Product Data Sheet BL.01, Superwool Plus Blanket, 18 April 2025, and Product Data Sheet SH.30, Superwool Plus Board, 1 January 2025, in each case the Chemical Analysis section. Accessed 17 October 2026.
- 171.Alkegen, formerly Unifrax: product data sheets Insulfrax 1300 HT Blanket, Form A-5276, as of 02/2024; Insulfrax LT Blanket, Form A-5182 Revision 2, as of 07/2024; Isofrax 1260C Fiber, Form A-5296, as of 07/2024; in each case the Typical Chemical Analysis section. Accessed 17 October 2026.
- 172.Morgan Advanced Materials, U.K. Thermal Ceramics Limited: Safety Data Sheets 203 (Cerafiber, Ceraform, Kaowool and others), 401 (Cerapaper, Kaowool papers and felts) and 111 (1260 SD Felt, Cera-Pack, Kaoclad, Moist Felt), in each case revision 1 June 2025, section 3 with the composition of the aluminium silicate wool and the binder contents. Accessed 17 October 2026.
- 173.European Chemicals Agency, Member State Committee: Support Document for Identification of Zirconia Aluminosilicate Refractory Ceramic Fibres as a Substance of Very High Concern, adopted on 9 December 2011; composition condition for the entry with index number 650-017-00-8 in Annex VI to Regulation (EC) No 1272/2008. Accessed 17 October 2026.
- 174.Promat: Technical Data Sheet PROMINA, as of 2017-09, Chemical analysis section. Accessed 17 October 2026.
- 175.Johns Manville: Safety Data Sheet Calcium Silicate Pipe, Block and Board Insulation, trade names HP Block Insulation, Thermo-12 Gold and Thermo-1200, version 2.2, revision 17 June 2019, section 3. Accessed 17 October 2026.
- 176.Imerys: data sheet Harborlite AquaPerl, July 2019, Chemical Analysis section. Checked for delimitation: Johns Manville, Industrial Insulation Data Sheet IND-200, Sproule WR-1200 Perlite Pipe and Block Insulation, as of 10 April 2025, without oxide analysis. Accessed 17 October 2026.
- 177.Palabora Copper (Pty) Limited: Vermiculite specifications, Typical Ranges for Major Components and Typical Ranges for Minor Components. Accessed 17 October 2026.
- 178.Aspen Aerogels, Inc., Northborough, Massachusetts: Safety Data Sheet Pyrogel XTE, as of 21 December 2023, section 3. Accessed 17 October 2026.
- 179.PyroShield: Safety Data Sheet PS-HB-32, PS-1400, PS-1400-V, PS-3600, PS-1800 Silica Fabrics and Silica Needled Mat, as of 22 March 2023, section 2. Accessed 17 October 2026.
- 180.Kamenny Vek LLC, Dubna: Safety Data Sheet Continuous basalt fiber products, brand Basfiber, Revision 2 of 25 October 2017, section 3. Accessed 17 October 2026.
- 181.WEICON GmbH & Co. KG, Münster: Safety Data Sheet Anti-Seize High-Tech Assembly Paste, product number 261000, version 1.03 of 16 December 2022, section 3; and Univar Solutions UK Ltd.: Safety Data Sheet Molykote P 37 Antiseize Paste, product number 60535, version 1.000 of 14 August 2022, sections 2.2 and 3. Accessed 17 October 2026.
- 182.International Maritime Organization: MSC.1/Circ.1321, Guidelines for measures to prevent fires in engine-rooms and cargo pump-rooms, published 18 November 2009; sections 3.3, 3.4, 5.1.1, 5.1.3, 5.2 and 5.3 as well as Part 2 Chapter 2 sections 1.1.2 to 1.1.5. Official reprint of the same wording: Maritime and Coastguard Agency, United Kingdom, Marine Information Note 579 (M). Accessed 17 October 2026.
- 183.tmax Group, formerly Thermamax: application pages Marine, Schienenfahrzeuge, Isolierungen für Baumaschinen, Power Generation and Automotive as well as the descriptions Metallische Isolierverkleidung, Textile Isolierungen and Abgasnachbehandlung; in addition the product catalogue Tmax-DryTec on underbody insulation around particulate filter and SCR modules. No publication date on the pages. Accessed 17 October 2026.
- 184.MAN Energy Solutions: MAN L32/44 GenSet IMO Tier III, Project Guide Marine, version 2.1 of 21 October 2021, sections 2.17, 5.9.2 and 5.10; and Everllence, formerly MAN Energy Solutions: ME Engine description, document 199 05 61-7.4, as of 23 June 2025. Accessed 17 October 2026.
- 185.Wärtsilä Finland Oy: Wärtsilä 46F Product Guide, document DAAB605814, edition 1/2020 of 12 February 2020, sections 5.5, 11.3.1 and 11.3.2. Accessed 17 October 2026.
- 186.InsulTech, LLC: Locomotive Insulation Solutions, page as of 11 July 2024, with the information on insulation material types, hot side materials and service temperatures; and the product page T1000, 2000, Custom Removable Insulation Blankets, page as of 3 June 2024. Accessed 17 October 2026.
- 187.Reference Datasheet TCG 2020 V16 for the MWM TCG 2020 V16 gas engine, prepared on 9 July 2024 by a plant contractor; exhaust gas temperatures at 100, 75 and 50 per cent load. An original version from the engine manufacturer was not available. Accessed 17 October 2026.
- 188.Johns Manville: Industrial Insulation Technical Bulletin IND-TB014, Diesel Generator Exhaust Insulation Selection, prepared 23 October 2020; information on exhaust gas temperature, two-layer installation, sheet metal jacket and fastening of stainless steel 304 as well as on the burn-out of the organic binder of the mineral wool from about 177 °C according to ASTM C447 section 5.7.2. Accessed 17 October 2026.
- 189.Morgan Advanced Materials, Thermal Ceramics: HRSG Industry Brochure, file identifier of 11 November 2016; product allocation per component for stack, silencer, flue gas duct, duct burner, floor and casing as well as the temperature and gas velocity figures for the heat recovery steam generator. Accessed 17 October 2026.
- 190.Olson, Scott; Morales, Kevin: Combustion Turbine Exhaust Ducts, Turbomachinery Magazine, 8 June 2017; information on liner sheets of 304 and 409 steel, bolts of 304, insulation thickness and temperature change during start-up. Accessed 17 October 2026.
- 191.ElringKlinger AG: Fact Sheet ElroShield M, Thermal and acoustic management for the entire vehicle, Shielding systems by ElringKlinger; information on the carrier layer material, the insulation insert and the operating temperature. No date in the document. Accessed 17 October 2026.
- 192.3M: Technical Data Sheets 3M Interam Mat Mount 1600HTE, February 2022, and 3M Interam Mat Mount 1650HTG, July 2025; mounting mats for catalytic converter, diesel particulate filter and end cone insulation with service temperatures up to 1,100 °C. Accessed 17 October 2026.
- 193.Aperam: Stainless Steel, The Material of Choice for Manifolds and Catalytic Converters, as of 2020; and product data sheet KARA Ferritic Stainless Steel K41X, FT_K41X_en_web, with 17.80 per cent chromium and oxidation resistance up to 950 °C. On the lower limit for stainless steels: British Stainless Steel Association according to EN 10088-1, at least 10.5 per cent chromium. Accessed 17 October 2026.
- 194.Rockwool Technical Insulation: Product Data Sheet ProRox WM 950ES, edition 17 July 2026, and ProRox WM 970 as well as the brochure How to prevent corrosion, Industrial Insulation, section 4 with the application description for boiler walls, furnaces, flue gas ducts and pipework and the figures for pipe sections up to 650 °C. Accessed 17 October 2026.