The photos above show some examples of cracks. The main photo shows a fire tube with a small crack in it, indicated by the red arrow. Such a crack is visually well visible if the inspector knows what to look for.
The first photo of the four shows a crack in the turning box, which can only just be seen with the naked eye. Therefore, the white background of the performed magnetic examination is present. In addition to experienced boiler experts, we also employ various certified magnetic researchers.
In magnetic research, a liquid is sprayed on the part of the boiler where there are possible cracks. The area is magnetized with a portable electromagnet and the cracks then light up extra, making them much more visible. In the second photo you can see how the crack becomes visible during the magnetic examination. Without the magnet, the crack looked like the last photo, so barely visible to the naked eye.
Magnetic examination is not possible in some cases. For example, if the metal cannot be magnetized, magnetic testing cannot be applied. An alternative is to apply penetrant research.
In penetrant testing, the material is first cleaned and then a penetrant liquid and a developer are applied, so that the cracks can become visible. Only 3 spray cans are needed for this, so such a set is easier to carry than a magnet set. That is why we mainly use penetrant examination for a first quick indication and for additional information in addition to the visual and magnetic examination.
Damage to Stork boilers
In the past, there have been occasional Stork boilers where cracks have occurred in the right-angled edge connection between the flat front or rear of the boiler and the cylindrical part. Stork boilers that actually have cracks in those locations must be rejected. However, Stork boilers were also regularly rejected where no cracks were present, but where unskilled researchers believed they were seeing cracks. We have carried out a second opinion investigation several times and in the past two years, 5 of the 6 Stork boilers were incorrectly rejected in the first instance. Therefore, if you have a Stork boiler where a researcher has found cracks in the angled edge connection, we strongly recommend that you ask for a second opinion. We will never hide cracks and if we carry out a second opinion, it is always tested by an inspection body. If the boiler is approved after the second opinion, then it is a safe boiler. Improper research can mean that you have to buy a new boiler, when it was not necessary.