Seeking help regarding corrosion of titanium equipment
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Leakage points have appeared under the heads of several 3000L titanium storage tanks at the facility.
This is caused by improper welding techniques that result in hydrogen pores. Hydrogen dissolves into the molten pool at high temperatures; when cooling and crystallization occur, if the supersaturated hydrogen does not have time to escape from the molten pool, it accumulates in the weld, forming pores. The solubility of hydrogen in titanium decreases as the liquid temperature rises, and there is a sudden change in solubility at the solidification temperature. During welding, the temperature in the center of the weld pool is higher than that at the edges, causing hydrogen in the center of the pool to diffuse not only toward bubble nuclei but also toward the weld seam. As a result, supersaturation occurs easily at the edges of the weld seam, leading to the formation of pores in that area.
Titanium is difficult to weld; laser welding must be used, and the technical requirements specified in GBT 37901-2019 for laser welding of high-temperature titanium alloys must be strictly followed
In Japan, welders of titanium materials must hold a certification
I have gathered some standard specifications related to titanium
The key issue lies in the straight edge section of the head; there are no problems with the welds of the rest of the cylinder. It is suspected that there was an issue with the heat treatment process for the head.
Are nickel-based alloy materials involved?
This is corrosion caused by iron contamination resulting from inadequate protection of titanium during processing
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