New welding method could halve cycle time
One of our customers in the nuclear sector was looking to implement a tube-to-tubesheet joint within a restricted space. To help determine the feasibility of the customer’s design we asked Nuclear AMRC to contribute their expertise to join efforts and face this welding challenge head on.
Dr Will Kyffin, head of the Nuclear AMRC’s welding team says:
“Thornhill’s heat exchanger was much smaller than the assemblies we usually work with, and right at the limit of what our robot and welding head can handle. The size and inertial mass of the robot meant that programming it to perform an accurate circumferential weld of just 8mm diameter was extremely challenging, especially as this was a new facility and the team were still finding out what it could really do.”
The welding head had to be customised for the job, with the large gas nozzle and shield removed in favour of a separate gas shielding nozzle, and laser power was reduced to just 2kW from its maximum 16kW. Initial trials showed that small tube-to-tubesheet welds could be successfully completed, with welding taking just over one second for each join. Allowing for movement time, a full tubesheet could be welded in a matter of minutes.
The project proved that a robotic laser welding cell can successfully join small tube-to-tubesheet assemblies, and the customer’s design can be manufactured to requirements.
Sean Murphy, Thornhill’s business development director says:
“While our heat exchanger design and manufacturing expertise has been proven over many years in the nuclear industry as well as other industry sectors, this project presented unique challenges. Sourcing independent, authoritative data from the Nuclear AMRC, one of the world’s leading research bodies in the nuclear field, on its feasibility was invaluable in presenting our solution to the customer.”