Engaging with NDT
15/02/2012
by Cameron Sinclair, CEO, BINDTThe following article has been prepared with the aim of stimulating debate with, and the engagement of, BINDT’s stakeholders. The views expressed in this article are the author’s own personal views, which do not necessarily reflect the views of BINDT.
The article is based on a presentation made at an NDT workshop organised by the Materials Knowledge Transfer Network (KTN), which took place in Oxford on 1 December 2011. The purpose of the presentation was to help ‘set the scene’ for some thought-provoking sessions on the day during which valuable insight from the participants was ‘captured’ which will help ensure that NDT is part of the government’s technology strategy.
So, why engage with NDT? Principally, the role of NDT is to augment and enhance the human senses. The vast majority of inspection of plant and equipment is carried out by suitably qualified and experienced people, who are able to visually examine those items, making use of their other senses as well as sight: ie aural – how the item sounds when operating; tactile – how the item feels when operating; and even olfactory – how the item smells when operating. Those of you who drive will have done this sort of inspection – you just know if your car doesn’t look, sound, feel or smell right!
NDT enables inspectors to search for flaws or potential defects that they could never detect using their own senses alone. This includes flaws that do not break the visible surface, flaws in areas that are inaccessible to the inspector and flaws that are just too small or have too small an effect to be perceptible to the human senses unaided.
Furthermore, NDT can be highly repeatable, which enables a ‘fingerprint’ of a pristine item (perhaps one that has just been manufactured and is about to enter service) to be acquired, against which inspection results acquired during subsequent inspections can be compared so as to identify changes which may indicate service-induced deterioration. By implication, of course, the acquisition of such data enables quantitative analyses to be undertaken: a measure of the remaining wall thickness or degree of corrosion wastage, for example.
Even if all the defects that might adversely affect the item’s fitness-for-purpose can be detected satisfactorily and assessed by using purely visual, aural, tactile and olfactory inspection alone, you might still want to engage with NDT. Whether you are using inspection during the manufacture of plant and equipment for quality control purposes, or while the plant and equipment is in-service to help control risk, you are likely to be keen to minimise costs. Therefore, you might consider engaging with NDT in order to improve the effectiveness or efficiency of the inspections.
Regarding effectiveness, the likelihood that a given defect is detected can be increased simply by increasing the sensitivity of the inspection by, for example, applying NDT, though – beware – this approach can also increase the probability of a ‘false-positive call’ (where a defect is reported that does not physically exist). By applying different NDT methods or techniques, or by independently applying the same method or technique more than once, the likelihood of detecting a given defect can be increased without increasing the ‘false-positive call’ rate. So, NDT can improve the effectiveness of inspection, but care must be taken to apply NDT in the correct way.
Regarding efficiency, I think it is a reasonable assumption that the desire to reduce the following is universal: the ratio of cost to value-added (which could include intangibles such as customer satisfaction), the amount of energy consumed (which is becoming an increasingly important factor) and the number of people employed, as opposed to subcontracted, specifically to undertake the task. It is also a reasonable assumption that the biggest proportion of the overall cost of an in-service inspection is incurred in taking the item out of service for inspection, preparing the item for inspection, providing safe access to the item for inspection and re-instating the item after inspection. If these assumptions hold true, then engaging with NDT may improve efficiency. For example:
- Use risk-based inspection (RBI) assessment methods to increase the period of operation between inspections, which may be justified by adding NDT to the scope of inspection – this approach could be termed more inspection less often (MILO).
- Use NDT to remove the need for inspectors to work at height or in confined spaces.
- Use NDT to inspect through coatings instead of removing/reinstating the coating.
- Outsource the provision of NDT services to specialist firms.
- Use NDT to acquire more accurate, quantitative data on which a less conservative remnant life assessment can be based so that the service life of an item or component can be optimised.
Now, how do you engage with NDT?
First, you may need to be prepared to challenge the status quo and embrace change, which may, in turn, require a change in the corporate mind-set away from an ethos of ‘if it isn’t broken, don’t fix it’ to an ethos of ‘hold onto the old just as long as it is good, and grab the new just as soon as it is better’. To help achieve this, you might seek authoritative, impartial advice about engaging with NDT from sources such as charitable institutes (like BINDT) and government organisations (such as the new Technology and Innovation Centres) and you might liaise with organisations with an interest in how you manage risk (including your insurer, your statutory safety inspection provider and any regulatory/licencing authority).
Incidentally, you might wish to ensure that you have suitable NDT expertise in-house in order to not be wholly reliant on your suppliers and other stakeholders for the information on which you will base your decisions. Employees with this expertise coming directly under your control should fully understand your undertaking and share your organisation’s ethos and standards. Indeed, you might even decide to acquire this know-how yourself! Whether it is you or a colleague endeavouring to create and maintain competence in NDT, you will find that there are a number of interconnected routes to different proficiency levels of NDT encompassing various academic degree qualifications (academic route), an apprenticeship scheme and various levels of certification (vocational route) linked to different grades of BINDT membership and registration with the Engineering Council.
Secondly, you might wish to engage with NDT strategically by setting aspirations that include outcomes that engagement with NDT can help you realise. If there are ‘off-the-shelf’ applications that help you engage with NDT, then all well and good, but if there is nothing available yet, you might consider engaging with organisations that can help you to innovate and develop new technology or applications. Membership of institutes, such as BINDT, is a good way of engaging with, and influencing the development of, NDT.
Finally, if you are involved in the design or installation of plant and equipment, you might consider engaging with NDT by ensuring that it is factored-in. One of the significant challenges facing the NDT profession is developing ways of applying NDT to plant and equipment as part of an in-service inspection regime. It is often the case that the respective designer/installer did not envisage (or chose to disregard) the fact that NDT would be required later in life. Although it keeps us NDT folk on our toes, it adds significantly to the through-life cost of the respective item.
As ever, your feedback is always welcome, so if this article causes you to think of something which might be pertinent, please get in touch via cameron.sinclair@bindt.org
