On secondary local heat treatment
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Recently, we manufactured a small tank with a diameter of 700 mm and a height of 1200 mm; it features angle steel legs. Brass pipes for steam circulation were coiled around the tank body, with a total of 12 coils. The lowest three coils were coiled around the angle steel legs, and the brass pipes at those locations suffered significant deformation – the minimum diameter of the 33.7 mm pipes was only 10 mm. The customer was not satisfied and requested that we replace those coils that had undergone excessive deformation and coil them again. We plan to modify the design of the legs by using support legs, so that the copper tubes can be coiled around the cylinder without deforming. The problem is that this tank has only undergone overall heat treatment; the copper tubes were installed on it after the equipment was heat-treated. Now we need to keep the upper few layers of copper tubes, so it cannot be subjected to overall heat treatment again. However, welding leg shims on the head requires welding work, and therefore the customer asked us to provide a process for localized heat treatment. As we are a small factory, we lack technical personnel with expertise in this area; we hope that those with more experience can help us out.
Check the new capacity regulations to see if welding after heat treatment falls under the exemption provisions; if it does, no plan is required.
If the customer requests it, and the contract stipulates it, then it must be done. Carry out according to the designed heat treatment parameters
Cut away the angle steel supports, apply local heating with a heating strip, but maintain insulation throughout
The heat-affected zone is 1.5 meters; localized heat treatment of the workpiece will inevitably have an impact on the copper tube
The new capacity regulations don’t have specific requirements, right? Local heating for insulation should work.