The Vasa Museum and Sandvik are taking on a critical project to replace 5000 wrought iron bolts on the Swedish heritage vessel. A national treasure, Vasa capsized and sank in 1628 as it prepared for its maiden voyage; it was raised from the bottom of the harbour in 1961 and carefully restored. The research and development cooperation between the museum and Sandvik may take over 5 years to complete and will involve the replacement of the majority of iron bolts with new bolts in highly advanced stainless steels from Sandvik, capable of withstanding the most demanding environments. The Vasa Museum chose the high-alloyed stainless steels from Sandvik over carbon fibre because they proved more capable, versatile and easy to work with. The process will be complex and slow as it is essential not to cause any unnecessary movement in the ship that could compromise its structure. The plan is to replace 3 bolts in one area at a time at an estimated maximum of 6 each day and approximately 1000 bolts per year. The bolts are designed to last a minimum of 100 years; they are non corrosive, safe, strong and flexible enough to fit any misshaped holes. Sandvik is using special super-duplex materials, as well as Sandvik SAF 2707 HD®, an advanced hyper-duplex stainless steel developed by the company. During the first year, the cooperation will see 1000 bolts replaced at which point they will all be carefully monitored to assess and determine the movement and stresses within the vessel.
