Under Water Welding - Article

Current Concerns - from Professional Engineering Magazine

Take welding – there's a good solid engineering skill to have. Good welders are worth their weight in gold, but even harder to come by are good underwater welders. And David Keats should know as he has made a successful career of it.

Keats started out as a conventional welder, but moved into what can be described, literally, as a very different environment. As a specialist underwater welder his abilities were in high demand, in waters both inland and offshore. He spent much of the 1980s working in the North Sea, where he says divers like him were considered expensive commodities. “We were there to do a very specialised job and there was no room for any baggage. If you weren't up to scratch you weren't given a second chance,” he says.

Keats says commercial divers, particularly offshore, are treated as costly tools, shipped in to do a job and shipped out as soon as the work is done. “It sounds glamorous, but the reality of travelling all over the world to different rigs and structures is very different.”

Of course there is the perception that all offshore work is higher up the danger stakes than engineering work on land. Where offshore diving is involved, Keats says the dangers are real, but there are mechanisms and legislation in place to keep divers safe. “You are working in a hostile environment and have to act accordingly,” he says. “There are real issues to be aware of, and unfortunately when something goes wrong it tends to do so in a big way.”

Safety Splash

As managing director of South-Yorkshire based Speciality Welds. Keats is now more involved in the safety aspect of commercial diving. Although he is still a certified commercial diver, the company does not provide a diving service as such. Instead, it acts as a consultant on general and underwater welding projects, assisting with specifications, quality control and quality assurance management, as well as training divers. It also manufactures and sells welding equipment and consumables.

The first mind block for the uninitiated to get past is how welding could possibly work underwater, as electricity and water do not mix, and power must be transported to the equipment. Keats says the problem of electrical conductivity underwater is dealt with using double-insulated welding cables, and that divers wear protective clothing so they don't get shocks. As a further precaution, current is only supplied when the diver uses it.
Only direct current is used, with a polarity chosen to maximise safety. Keats says good practice is to have the diver holding the cathode, with the work to be welded as the anode to further reduce the risk of shock, and also leakage of current into the water. “As long as the safety issues are understood and acted upon, underwater welding is safe,” he says. That said, Keats has fallen foul of current leakage in the past – and when it encapsulates the diver the result can be dissolved fillings.

Unlike scuba diving, where all breathing equipment is carried by the diver, most commercial diving is performed with an umbilical link from the surface supplying oxygen and communication to the diver via their helmet. And on top of all the diving clobber, the welder still needs eye protection, which tends to be in the form of a flip-down visor.
In the past, says Keats, most people training to become commercial divers had an engineering background of some sort, which came in useful because of the similarly practical aptitude and capability aspects required of divers. However, engineering skills are no longer a prerequisite, he says.
Much of the training work Speciality Welds does is in collaboration with the Underwater Centre at Fort William in the Scottish Highlands. As the UK's national commercial diving school, the centre provides qualifications approved by the Health and Safety Executive.
Unfortunately, says the centre's chief diving instructor, Alf Leadbitter, there is no way of telling at first glance who will make a good commercial diver, but there is certainly a steady demand for qualified underwater engineers. There is plenty of scope for underwater labourers too to do general cleaning and maintenance jobs.

Leadbitter says the main call for commercial divers tends to be for inspection purposes. “This might be periodic visual inspection of underwater jackets and rigs or non-destructive testing. Obviously it's better to have an engineer who can dive rather than having to rely on data collected by non-engineering divers, as the engineer can problem solve on the spot, rather than having to go back and report any findings and wait for further instructions.”

Most divers do what he calls this “peculiar” job because of the passion they feel for it. “The best part has to be getting paid to do what you enjoy, but it must be remembered that really the diving is only the means to get to work – it's just more exotic than taking the bus. At the end of the day, you are paid for the skills you use once you've got there, not because you can dive.”
The passion for diving that Leadbitter talks about is also what attracted Phil Richards, director of Commercial and Specialised Diving Services in Bournemouth, Dorset. What keeps Richards in the industry is the wide variety of work. Although much of it is structural engineering, covering remedial and new build work on piers, locks, canals and bridges, he finds that underwater work on ships is the next most common form of employment for commercial divers. “Work off ships typically includes cleaning and replacing propellers, painting hulls and performing upgrades underwater,” he says.
“There are also instances when we've had to dive in other facilities like sewage tanks and pipelines. We're not always diving in water either, which can be an experience not to be forgotten.”

Strict Regulations

Perhaps one of the biggest bugbears across the commercial diving sector is caused by the hiring of recreational divers to do commercial work, not just because of the lost revenue, but because of concerns that safety is being neglected.

Richards says: “We often find that the simple jobs are taken on by recreational divers, all too keen to get a bit more diving in. Commercial divers can't compete on economic terms because of the safety legislation we must adhere to.”

For example, Richards says the diving at work regulations specify a minimum of four people at a diving site for safe operation: an operator, the diver, a rescue/standby diver and a diving attendant. “In a good diving team the person doing the work, the diver, should not have to be aware of anything to do with the actual diving, but should be able to get on with the work involved, almost as easily as if they were doing the job on dry land,” he says.
Remotely operated vehicles, or ROVs, have taken over some of the more hazardous roles, but there are some situations in which they are next to useless, says Richards. “However good you are at working with ROVs, they are no good for inspection work in zero visibility conditions. In those cases a working diver has to carry out the inspection by touch.”

A Visible Difference

David Keats of Speciality Welds says the main difference between welding in air and underwater are safety related. “Most of the time we use manual metal arc welding, which is widely used in general engineering, but underwater the environment provides completely different conditions. The skills you need are slightly different and how you weld also changes as the way a weld progresses is different.”

The main issues underwater are visibility and skill. The latter is what makes a good welder whether above or beneath water, but Keats believes the underwater environment can only compound a lack of skill. “As for visibility, if you can't see what you're doing, how can anyone possibly expect to produce a high-quality weld? It can only be guesswork.”

To address this, Speciality Welds has developed equipment that takes the guesswork out of producing high-quality welds in low- and zero-visibility conditions. For a start, the Hammerhead wet-spot welding system needs none of the traditional cleaning before welding, and can even work through painted structures. It can be used by divers and robots alike because of its automated control system which sets times for the first current level to pierce the top and base material and the second current level that joins the material together.

Keats says the objective was to create a magic box that removes the problem of poor visibility, and with it even divers with little training can produce good quality welds.

http://www.specialwelds.com/underwater-welding/underwater-welding-article1.htm