Working with penetrant testing at lower temperatures

Just recently, I have been in a discussion about the reporting requirement given in ISO 3452-1:2021 ‘Non-destructive testing – Penetrant testing – General principles’ and in particular the requirement to consider and report the test temperature. In Section 9, it states that the test report shall contain the following information: (g) test temperature.

In the UK, we are moving into the colder time of the year where the temperatures are dropping and it is not unusual to have periods in which the ambient temperatures are not above 10°C. So, there will then be a need to manage working with penetrants at these lower temperatures.

The conversation moved on to the methodology of taking the temperature, including issues such as: whether it should just be taken at the beginning of the testing, especially if it is a large component or large batch of components; what measures of calibration of the equipment are in use for measuring the temperature; how to manage on-site conditions and such instances where the components are delivered on an open bed lorry and are at a lower temperature; and how long the components need to be in the workshop for to raise the temperature and whether different metals would affect this along with the component dimensions. Some clients will understand the effects that temperature will have on the consumables but others may not, with the potential for difficult discussions with them. There is the potential for the penetrant testing stages to be extended when the temperatures are lower, but will the client pay for this? To bring the components up to an acceptable temperature or to increase the contact times will again incur costs and there is a question of who will be responsible for this, especially with the increases in fuel costs in the UK. There are also issues when working with elevated temperatures, which do not happen too often in the UK but also need consideration.

The client and others may possibly think that the penetrant testing method is simple and basic, but the one consideration of temperature can lead to so many more challenges. This is where a good Level 3 earns their salary, working between the tester and the client, understanding the requirements and facilitating the conditions so the Level 1 and 2 testers can meet these requirements. There is further guidance on how to manage the temperature reporting requirements and how to accommodate different temperatures within the suite of standards to which the Level 3 would be referring. The clients also have a significantly wide range of different approaches to the requirements; some do not have any concerns, while others supply digital thermometers and work instructions on what is to be recorded and how to manage different temperatures.

I recall being told of a fabricator who decided to have a go at testing some in-service welds and surrounding areas with penetrant and found some fatigue cracks, which were repaired. They rechecked the repairs but found additional cracking away from the repairs that also looked like in-service cracking. At this point the professional testers were called in and their immediate comment was that it looked like a blood bath with red penetrant everywhere. After extensive pre-cleaning and controlled application of the testing process, a much clearer result was obtained showing the true extent of the defects so that effective repairs could be made.

Through the British Institute of Non-Destructive Testing (BINDT) there has been an initiative to bring into the fold those people starting out in non-destructive testing (NDT) and condition monitoring (CM) and the Early Careers Branch has been very successful in doing this. I did consider whether it would be appropriate for myself, so I checked in the Yearbook to see when I joined BINDT. It transpires it was on 14 October 1981, so by the time you are reading this I will have been a member of the Institute for 40 years and am probably past the early career stage, but I am still learning something new daily. Another indicator of my maturity was the recent award that I was given: the Personal Contribution Award. I think that the award title is a little limited as there have been many people in the NDT community that have helped my contribution and I would like to thank them all.

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