Can pre-welded parts be added if they are missing after the container manufacturing is completed?
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This post was last edited by qwl on 2018-3-7 at 10:32. Hydrogenation converter. Specifications: Φ2700mm×8650mm×20mm; material: 15CrMoR; pressure: 1320KPa; temperature: 450°. Due to a mismatch between manufacturing and design, the containers shipped from the factory lack platform pre-welded parts. 1. The design of all weld attachments on the equipment is complete. Including: operation platform connectors ； Insulated support pre-welded parts ； Lug support plate ； Nameplate bracket ； Ground plates, etc. After overall heat treatment, welding on the equipment is no longer permitted. How to solve the problem of missing pre-welded parts? 2. Is it possible to repair the welded parts using a low current, by welding in staggered sections, and by controlling the welding temperature?
It can be welded, but post-weld heat treatment is required.
Adding pre-welded parts now carries a high risk; let’s see if there are any domestic cases for reference.
Do we need to redo the voltage withstand test?
Personally, I recommend two methods: 1. Weld the pre-welded parts at intervals away from the heat-affected zone of the joint, and then apply local heat treatment using an electric heater. This plan requires approval from the person in charge of the design unit. 2. The ladder platform uses an independent steel structure and is not fixed to the equipment. The insulation structure uses insulation nails; these nails are bonded to the equipment with high-temperature resistant adhesives in order to support the insulation layer
From the perspective of equipment safety, if so many pre-welded parts are to be welded, overall heat treatment is necessary; local heat treatment is not a viable option. Of course, the second suggestion put forward above is still worth considering.
If only a very small number of pre-welded parts need to be welded, it is recommended to keep the weld leg height under 6 mm, carry out thorough preheating and post-heating, but avoid any post-weld heat treatment.
Welding electrodes made of nickel-based alloys can be used, and the possibility of omitting post-weld heat treatment will be discussed and determined.
I am also considering an independent combined steel structure platform.