Heating of rivets
Every service call is unique. However, we received one recently that was truly extraordinary. Tom Smith, machinist for the 1925 steamship ‘Saltsjön’, rang. Could we help restore the old vessel by heating rivets for new, below-deck flooring?
It sounded interesting, so we packed a Minac mobile induction heater and whizzed off to a boat dock in Stockholm, Sweden. Tom met us there, together with colleagues Janne Lundell and Mats Söderlund.
We began with a tour of the ship, a beautiful vessel steeped in history. She had transported Stockholm
residents for many years, even serving in winter as an icebreaker. Now officially listed, she was undergoing extensive renovation.
Old Method, Modern Twist
Heat induction’s many pluses were apparent from the start. Traditional heating methods are time-consuming and uncomfortable. If you use an on-site furnace, great amounts of coal and hard work are required to keep the temperature high. What’s more, traditional riveting is cramped, dangerous work. Gas isn’t much better. It’s time-consuming, and it creates an uncomfortable working environment.
Instead, we simply brought the Minac aboard (it was easier than it sounds, it only weighs 50 kilos), connected it to electricity and water and started it up. Better yet, the induction coil (the actual heating tool) lies at the end of a 5-meter, water-cooled cable so it could easily be taken below-deck. Talk about an improvement in working conditions! Within seconds the rivets were glowing.
The work went quickly, and after a few hours we were done. A tong lifted the heated rivets, the bucking bar was positioned and a pneumatic hammer battered each rivet. Meanwhile, the next rivet was being heated. Work on “Saltsjön” was a successful combination of a proven method (riveting) and modern technology (heat induction). And the advantages of heat induction were obvious: flexible equipment, fast and efficient heating and a comfortable working environment. It was satisfying to help Tom and his co-workers and see how modern technology can preserve living history. To see how the restoration is going, log on to www.saltsjon. nu. If you are interested in what induction could do for you, just visit:
Here’s the team that carried out the “Saltsjön” induction work. They are (left to right): Leif Rahunen of EFD Induction, Janne Lundell, Mats Söderlund and Tom Smith.
A rivet is heated to 1100 degrees C in 7 second, consuming only 0.03 kWh.
Once the rivet and the bucking bar are in place, a pneumatic hammer balters the rivet from above