Thread Content
Precautions for repairing stainless steel pressure vessels 01 When repairing stainless steel pressure vessels, it is necessary to avoid scratches on their surface caused by sharp or hard objects; if work needs to be done inside the vessel, protective measures such as using padding should be taken. 02 Stainless steel sheets should be cut using plasma cutting or mechanical processing; when mechanical processing is used, the machine tool must be cleaned thoroughly. Use of carbon arc gas gouging for cutting is not permitted. When rolling stainless steel into coils, the coil rolling machine should use iron-ion-free materials to cover the surface of the rollers. 03 During the repair process of replacing or patching the housing, tools such as wedges and shims that come into contact with the housing surface and are required temporarily should be made of stainless steel suitable for the housing. 04 When repairing stainless steel pressure vessels that require resistance to intergranular corrosion, it is necessary to strictly follow the welding procedure specifications during welding, carefully control the temperature between weld layers, and polish away any carburized layers when cleaning the weld roots. The repaired area must still meet the original requirements. 05 Before repairing stainless steel pressure vessels, oil and other contaminants at the joints should be cleaned using acetone or alcohol. The cut area should be created by plasma cutting, and it must be polished until it has a metallic shine. When welding, arcing should not be initiated directly on the surfaces of the stainless steel that are not to be welded. When using manual arc welding, a splash guard zone of 100 mm around the joint is required to help remove any splashes. 06 Stainless steel pressure vessels after repair must be pickled and passivated; generally, the immersion method is used for pickling and passivation, but the wet wiping method or paste application method can also be employed. 07 The surface of stainless steel after pickling shall show no obvious signs of corrosion, nor any patches with uneven coloring; the surfaces that have been welded or heat-treated shall not exhibit any oxidized colors. After pickling, it must be rinsed thoroughly with water; no residual pickling solution is allowed. The passivated stainless steel surface should be rinsed with water, and once it is neutral, the water droplets should be dried off. 08 For stainless steel pressure vessels that require resistance to intergranular corrosion, a check of the passivation film must be carried out after surface treatment. This check is generally performed in accordance with the specifications given in the drawings; if no such specifications are provided in the design drawings, the blue-dot method is used to examine the passivation film.