If stainless steel sheets are used in hydrogen presses without being inspected after processing, it poses serious risks
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If stainless steel plates are used in hydrogen compressors without being inspected after processing, it can pose serious risks. Problem: A circular plate with a thickness of 88.9 mm 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 cracks were caused by fatigue. Fatigue cracks originate from the opening in the outlet nozzle and propagate both radially and thicknesswise in the plate. Analysis: 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 circular plate 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. Note: Therefore, defects should be minimized during machining, and a penetrant inspection should be carried out after drilling. Additionally, the external pipe mounting holes on the plate should be placed as far away as possible from the gas inlet and outlet connections.
Using stainless steel plates that have been processed without inspection in hydrogen compressors poses the following risks: 1. Residual stresses and local heat gradients may arise during processing, and failing to conduct inspections could lead to crack propagation in the defective stainless steel plates once they are in use. 2. 17-4PH stainless steel is sensitive to hydrogen absorption; cracks or defects present during use can lead to structural damage. 3. Design and manufacturing issues of circular plates, particularly the periphery and openings, are prone to become initiation points for fatigue cracks. 4. If the crack develops to a severe extent, it will significantly reduce the effective thickness of the plate, affecting its load-bearing capacity and potentially leading to pressure instability or failure. To prevent these risks, penetrant testing should be conducted after machining to reduce defects, and care should be taken to avoid placing mounting holes in areas prone to cracking. .