Steve Grindrod is one of the world’s leading experts in underwater inspection and has been leading the development of Non-Destructive Testing training at The Underwater Centre for the past three years. Here he tells us how he got started in commercial diving, and talks about the developments in the underwater inspection industry.
“I left school before I was 16 with a CSE Grade 1 in Geography – I was told that with my expertise in Geography I should at least be able to find the Job Centre! I ended up as a freelance computer operator, working in several computer centre’s around the country earning, what was at the time a considerable amount of money and blowing the lot, something I was pretty good at. My main spare time activities at the time were parachuting and flying and I started doing occasional diving jobs in my spare time to help finance both. In fact I took unofficial time off work to do them because they paid better. It’s unlikely any of my old employers are still around so I can admit it now! My double life as a computer operator and commercial diver continued with the commercial diving getting more and more frequent and my employer getting more and more fed-up with me. In 1979 it was decided, by mutual consent, that this could not continue, a choice had to be made and commercial diving won.
“I went back into education in 1979 to study Underwater Technology, which gained me a place on a Government sponsored commercial diver training course. At that stage I’d already been involved in the inshore diving industry for some time, but the qualification I gained on the course enabled me to enter the offshore diving industry and eventually train as a saturation diver*.”
“Not a lot has changed as far as divers are concerned over the years. However, in inspection diving the use of ACFM (Alternating Current Field Measurement) for assessing welds has increased and in some cases the use of MPI (magnetic particle inspection) as a supplementary technique has also increased. The latter was not foreseen when ACFM was first starting to be used but then the inherent drawbacks of ACFM started to be noticed and MPI made an unexpected come back. Hence, in part, companies now want as many, or more, 3.2U divers i.e. MPI qualified as 3.1U divers. The two techniques are complementary and possibly that philosophy is another change in so far as subsea inspection is concerned.
“Possibly due to the costs involved in underwater inspection particularly, complimentary inspection systems are being developed and used increasingly. This has been the case with topside inspection for a while. I’m in the process of writing the last section of a new U/W Inspection manual and in it I have written about three techniques which have really come to prominence over the past five to ten years; phased array, guided wave and time of flight diffraction (TOFD). These are all ultrasonic inspection techniques which lend themselves to auto and semi automatic applications subsea.
“There are other systems which incorporate digital radiographic capabilities as well, radioactive source is placed inside the pipe under a circumferential ‘girth’ weld using a pipe ‘crawler’ and then the digital radiographic processing system is placed on a jig over the weld on the outside of the pipe. The radiographic unit then transits around the weld using an ROV or diver attached chain or frame and the end result is a complete colour radiograph of the whole weld. This can be recorded and/or transmitted while the process continues on the next weld.
“The trend for recording inspection data in real time and it being interpreted by topside technicians continues and is increasing. Guided Wave Testing (GWT) is one such method which is now available to inspect/monitor subsea pipes and tubular structures. The test rings can be applied either by a diver or an ROV.
GWT can utilise both temporary or permanently installed test rings which are attached to convenient parts of the pipe or tubular structure which is clearly shown in the video below, supplied by Genesis and Guided Ultrasonics Ltd.
Other systems are under development that will utilise AUV technology, the AUV will be pre-programmed to go around a structure, a field or part of a field carrying out routine visual inspection using HD video, possibly 3D. They will also carry CP (corrosion protection) and current density measuring equipment as well as being able to lock on to data upload and download ports subsea.”
“What makes a great NDT diver? I would say attention to detail and the ability to read, understand and follow detailed instructions and procedures are the main ones, along with the every present requirement for any commercial diver; tenacity. You have to make it happen even when things aren’t going well and equipment isn’t working right; the client isn’t interested in excuses, they have spent a great deal of money getting you there, they expect results; perfect, accurate results. How you get them is down to you, just do it.”
Are you interested in becoming an inspection diver? Do you have experiences of the changes in underwater inspection over the years? Leave a comment and let us know.
*Steve did his first commercial saturation dives on the Uncle John, which you can read about here.
Thanks to Genesis & Guided Ultrasonics Ltd for allowing us to display this video.
