Corrosion protection for process pipeline supports
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For pipelines with a large inner diameter that require insulation, pipe supports equipped with protective plates must be used during installation. These pipe supports are prefabricated in advance; when they are welded to the pipeline, the side of the protective plate that comes into contact with the pipeline may suffer from corrosion due to overheating, and this could pose a risk of corrosion to both the pipe support and the pipeline over time. I would like to ask the experts here: has anyone encountered a similar situation, and how did they resolve it? I hope all the experts will be kind enough to share their insights!
Weren’t these guards made together with the pipes, going through sanding and painting? :o
Such pipe supports are generally not welded to the pipelines, but are fixed using U-shaped clamps.
Anti-corrosion treatment was applied before welding, but after the two are welded together, hot spots form at the contact surface, causing the anti-corrosion paint to peel off.
In other words, the installation regulations for pipelines specify that pipe supports with guards cannot be welded directly to the pipelines; instead, they must be secured using U-shaped clamps. Is there a specific source for this standard?
Well, we all weld the guards and pipelines together first, and then carry out anti-corrosion treatment as a whole. Welding of the guard plates to the T-shaped plates of the pipe shoes, with on-site repainting.
There are various types of pipe supports, and for insulated pipes as well, there are multiple options. Refer to Figure 3 in the HGT21629-99 standard for pipe support diagrams; the issue of how welded pipe supports with protective plates affect the anti-corrosion coating is generally not discussed. The materials for the prefabricated welded supports are sandblasted, derusted, and painted separately; the individual pipes are also derusted and painted. If welding is required, the welds can be repainted after welding. It will not go into detail about the issue of the topcoat on the side where the guard plate is in close contact with the pipe being damaged by the welding heat.
There’s no good solution; one can only handle it manually and then repaint it