Why should I test my vessels regularly?
In order to comply with HACCP requirements, processors need to identify Critical Control Points, and/or areas within their production facilities that may cause contamination of the product. Examination of internal surface areas in sprayer dryer chambers, processing and holding tanks, and silo’s has now become common practice in the liquid food industry.
How often should I examine my vessels?
Vessels, some of which are positioned within the production area, are regularly checked for cracks. Normally this is undertaken every six months, searching for pinholes, cracks and other defects inherent in this equipment. Defects may occur at any time during production, or when the vessel is opened for servicing or cleaning. Some defects are even detected when the vessel is new, either from the manufacturing process when cracks emanate from welding or from fitting attachments.
These defects may cause product contamination in the form of bacteria or chemical leak into the product via the coolant jacket or proliferation in cracks, pinholes or insulation around the outer surfaces.
I have used traditional methods for testing my vessels, what is the best methodology now?
As vessels have inherent defects that can cause product contamination, there has been one method developed over the years to help prevent this; dye testing. This test method has shown inconsistencies that will be described in the following questions.
EIT International has developed Magnerscan to address these inconsistencies.
What are the environmental issues with testing?
Traditional methods have many environmental issues. Chemicals and dyes have to be manufactured for tests and disposed of afterwards, mainly into the plant effluent system and then into a watercourse.
The Magnerscan test system uses battery powered, electronic sensors that can be used for many years without consumables, addressing environmental concerns.
I would like to detect cracks before they leak; is it possible to know how deep these cracks are?
Using traditional dye-test methods, this would not be possible as the test reveals dyes that hold in all types of discontinuities, including scratches. When viewing fluorescent dyes in UV light, it is impossible to correctly assess these defects or determine their depth.
The Magnerscan test method is able to accurately measure the size of the defect depth. This means that the processor can assess the seriousness of the defect before it will become a problem and the vessel fails. Determining the depth of a defect is particularly important in spray dryers where the vessel is working under pressure and deep cracks may allow contaminates to be sucked in from the exterior of the vessel.
Can you prove the accuracy of the test?
Dye testers may say that their method has been used for many years, so it must work, even though the procedure used is not a qualified test method normally used for dye testing in the aerospace and nuclear industries.
Magnerscan uses a laser drilled test block with verified cracks at different depths to calibrate it crack depth detection. Additionally, Magnerscan can check for cracks in all directions at the same time.
How safe is the equipment that you will use for the tests?
Dye testers will mostly be carrying electrically operated equipment, either 110v, 240v or 415v while spraying dyes and water around vessels; electric shock is always a possibility. Additionally, the dyes and water have a viscous quality and create a risk of slipping or falling inside of the vessel. When spraying dyes, there is also an issue with inhalation.
Magnerscan is a dry test, operating with battery power, involves no viscous liquid and eliminates the above risks.
How much production downtime is needed for the test?
Dye testing requires the vessel to be thoroughly cleaned, then dyes applied using a spray gun, wait for approximately one hour, wash off dye and another half an hour to view. So, a considerable time is involved, 4-6hrs.
Magnerscan testing is carried out very quickly by simply scanning or ‘swiping’ over the vessel surface. It has been shown that Magerscan is 200 times faster than eddy current testing.
Would your test method find defects that are closed or filled with product residue?
Dye testing will not normally penetrate a closed defect due to surface tension. Also, any residual product, especially if greasy, will stop the dye from registering the defect.
Magnerscan will definitely find these defects as it penetrates any residual product or closed crack defect. This can be proven by placing insulation tape over the pre drilled test block and scanning across it’s surface, where a defect will then be highlighted.
Will your Inspector be trained and qualified?
In accordance with our Quality Manual, all Inspectors are trained in the use of the relevent test equipment and methodology, by way of annual training and qualification certification.
Is your equipment calibrated and serviced regularly?
In accordance with EIT International’s ISO 9001 accreditation, all test equipment has unique numbering and is returned for annual upgrading when necessary, servicing and calibration. When calibrated, the equipment will stop working automatically after twelve months if not returned for it’s annual check-up. This ensures that calibration of the equipment is keep fully updated.
Traceability is very important to the producer, how can this be done with a vessel test?
Traditionally, a certificate will follow a dye test.
EIT International has introduced full traceability for condition monitoring of vessels. This includes GPS location, date and time stamp, defect location via our defect mapping system with laser technology. This is imperative for ISO accredited organisations.