The use of calcium-containing insulating materials can lead to the formation of carcinogenic chromium(VI) compounds (chromates). We have been reporting on this for three years now!
For a long time it was quiet on the part of the manufacturers, now however there is movement, even if as always well hidden and without large medium echo.
After all, it is now (finally) warned!
Many years too late and certainly not accessible to everyone and easily found, but the wall of silence breaks!
Let's take a closer look at the chromate alert of a global market leader:
For the first time, the occurrence of "yellowish deposits" during the dismantling of mineral wool insulated systems is reported, truly a 180° turnaround, because until recently, the mineral wool industry only said succinctly "is not known to us"!
The manufacturers of such materials try to justify themselves by not associating the alkali or alkaline earth metals (especially calcium or sodium) contained in today's insulating materials with the formation of chromates and blame it solely on the chromium content of the hot parts to be insulated.
At the same time, however, insulating materials (containing alkali and alkaline earth metals) are marketed with chromium-containing quilting wires and grids.
So if it is claimed that chromium alone is responsible for the formation of chromium (VI) compounds, shouldn't we at least remove the chromium sources from the materials to protect consumers?
As recently as May 2021, in an injunction proceeding against a Polish company reporting on chromate formation, it was very important to an insulating materials association that it was not reported in a blanket manner on chromium(VI) compounds, but - in connection with mineral wool - explicitly on the carcinogenic chromium(VI) compound calcium chromate.
Already in the course of the court hearing, it quickly became clear even to the plaintiff, a German trade association of the mineral wool industry, that the argumentation of "gaseous chromium (VI)" somehow materializing and depositing somewhere is not tenable.
Now, two years later, however, this theory is being put forward again.
There are several scientific studies that mineral wool, which naturally contains alkaline and alkaline earth metals such as calcium and/or sodium, forms the carcinogenic chromium (VI) compound calcium chromate when in direct contact with hot parts containing chromium and at temperatures of 300°C and above.
Here, too, it is completely disregarded that there are very well scientific investigations which exactly prove the formation of calcium chromate or sodium chromate in connection with alkaline or alkaline-earth insulating materials on heated chromium-containing stainless steel plates.
Incidentally, no gaseous chromium (VI) was formed in these experiments!
The thermochemical formation of calcium chromate is as simple as it is disturbing; it does not require - contrary to some claims - temperatures above 700°C/800°C, high operating pressure or high humidity.
Chromate formation is a dry and natural chemical process, starting at temperatures above 200°C.
Depending on the type and volume content of the alkali or alkaline earth metals in the high-temperature insulation, the carcinogenic chromium (VI) compounds are formed in a temperature-dependent manner, as the graph below shows:
As the mineral wool manufacturers themselves state, the insulating materials "...consist of fibers with a content of alkali and alkaline earth metal oxides (Na2O+K2O+CaO+MgO+BaO) of more than 18% by weight.... ", and thus have exactly the ingredients required for the formation of, among other things, calcium chromate (CaCrO4) or sodium chromate (Na2CrO4), provided there is direct contact with chromium (III) compounds under the influence of temperature.
especially in mineral wool products quilted with wires or wire meshes containing stainless steel, all the ingredients for chromate formation are combined in one product and, when heated, can lead to the formation of the carcinogenic and environmentally toxic chromates.
This creates a double dilemma for the insulation industry:
All common insulating materials used for high-temperature applications contain at least one, usually even several alkali or alkaline earth metal(s).
Many of the above-mentioned insulating materials are already reinforced with elements containing chromium (III) in their delivery state.
In this respect, the formation of calcium or sodium chromate is to be expected even if hot parts not containing stainless steel, such as machines, pipes, aggregates, etc., are insulated!
The carcinogenic chromates are not only formed between insulation and the component to be insulated; they can also occur on the outside of insulating elements when they come into contact with hot parts containing stainless steel!
The following picture demonstrates the interaction between temperature, alkali or alkaline earth metal and stainless steel very clearly.
A metal frame made of stainless steel, whose alloy contains chromium (III) (Cr2O3), is welded to the high-temperature part (channel) and thus conducts the channel temperature to the outside of the metal frame.
As can be clearly seen, the coating of the insulating element is thermally decomposed in the radiation area of the frame.
Now there is direct contact between the chromium-containing stainless steel alloy of the bracket and the calcium-containing surface of the insulating fabric made of common E-glass, as used in the insulation industry by the kilometer.
Also evident is the direct welding of the bracket to the duct, which in turn promotes almost full temperature dissipation between the duct and the frame; thus, exposing the outer surface of the insulation to the internal temperatures of the system.
According to the insulation manufacturer, high temperatures AND water vapor are required for the gaseous chromium (VI) compounds to form.
Gaseous chromium (VI) compounds therefore tend not to be visible in pictures, but the yellow deposits are very recognizable wherever stainless steel components and insulation elements come into contact.
The yellow powder residue is the chromium (VI) compound calcium chromate, a solid and not a gas; a thermochemically formed compound of calcium and chromium.
The powder residues would also have occurred if a fiber mat had been used instead of an insulating pad, because this also contains alkali and alkaline earth metals.
With the publication of further warnings from the industry, which are becoming more numerous and point to the safety risk for humans and the environment in connection with the release of chromium (VI) compounds when using today's insulation materials, one thing becomes clear:
There is a worldwide chromate alert, because calcium and/or sodium-containing insulations are simply everywhere.
The mineral wool industry will have to face one question, namely that of responsibility in #TheChromateDisaster.
We (the editors) have received correspondence that clearly proves that trade associations must have been aware of the formation processes as early as 2020/2021.
The major engine and turbine manufacturers are also aware of the formation of chromium (VI) compounds when using insulation containing alkali and alkaline earth metals.
It can be assumed that both parties knowingly or unknowingly reassured each other, as is customary in established business relationships.
In many individual discussions, however, we often heard the comment that the insulating products are not banned, after all.
In fact, it is completely irrelevant whether something is banned or not!
With the emergence of chromates and their possible release, every employer is legally obligated to initiate a whole package of measures to protect against illness and environmental damage, and here it only plays a minor role at first who or what can be held responsible for the emergence of the so-called CMR substances*, this analysis only becomes substantial later.
*CMR - carcinogenic, mutagenic, reprotoxic
It is the chromate itself which may only be handled under the strictest conditions and these legal regulations have existed for many years!
However, if one knows how these hazardous substances can be formed, it is also the duty of the contractor to reduce the renewed or further formation, at best to prevent it (substitution testing duty).
If it is possible to prevent the formation of chromate, e.g. by using alkali and alkaline earth metal-free insulating materials and systems, then these possibilities must also be exhausted immediately.
The answer to the question why today's market leaders do not consider it necessary to warn more intensively or to offer alternative products is left to the imagination of each individual.