The attachments on the hydrogen compressor have developed numerous fatigue cracks due to inadequate design and manufacturing, and the problem is serious
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A circular plate 88.9 mm thick mounted on the hydrogen compressor (made of 17-4PH stainless steel) is used to maintain pressure. A large number of cracks were found on the plate, which was immediately replaced, preventing a catastrophic failure. Inspection revealed that the cracks had penetrated deeply, leaving only 25% of the plate’s effective thickness. Tests indicate that the crack was caused by fatigue. Fatigue cracks originate from the opening in the outlet nozzle and propagate both radially and thicknesswise in the plate. Because 17-4PH stainless steel is sensitive to hydrogen absorption. But the main causes of corrosion damage are still design and manufacturing issues. There are four openings on the edge of the disc for connecting to the compressor housing. The plate also has openings for the hydrogen inlet and outlet connections, and there are 2 threaded holes near each opening for the assembly of external pipes. During drilling, high residual stresses and local heat gradients generated by machining cause cracks to form, which further develop over time as the component is in use. Therefore, defects should be minimized during machining, and a penetrant inspection should be carried out after drilling. Furthermore, the external pipe mounting holes on the plate should be placed as far away as possible from the gas inlet and outlet fitting openings.
The 88.9 mm thick circular plate used in the hydrogen press is made of 17-4PH stainless steel, and its main function is to maintain pressure. The plate developed severe fatigue cracks, reducing its effective thickness to only 25%; failure to replace it in a timely manner could lead to catastrophic accidents. The main causes of the cracks are design and manufacturing defects, coupled with the sensitivity of 17-4PH stainless steel to hydrogen absorption. During the manufacturing process, drilling operations generate high residual stresses and local thermal gradients, which promote the formation and propagation of cracks. To prevent similar problems, it is recommended to conduct penetrant testing after machining to reduce defects, and to position the mounting holes for external pipes as far away as possible from the gas inlets and outlets. .