Structural integrity of pressure vessels repair welding joints

What is it about?

Vertical cylindrical vessel-chambers as a part of coal — drying plants, whose purpose is to collect wastewater, are supported at 3 points in upper dish head area and are made of fine-grained Mn steel plates, joined by welding. Significant thinning and leaking in upper dish head area of the vessel occurred due to original design provoking an intensive abrasion, cracking and rupture. After reconstruction, in the upper zone of cylindrical shell, two new joints were made in sity by manual arc welding, with subsequent, local post-weld heat treatment. However, cracks appeared firstly in new welded zones in radial and axial joints, and then in zones of openings.

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Photo by Museums Victoria on Unsplash

Photo by Museums Victoria on Unsplash

Why is it important?

Since welding with subsequent heat treatment could only be used twice to repair the welded joints, it is clear that in the areas repaired several times (up to 7) proper mechanical characteristics of the material is rather difficult to maintain.