Since the sand shell modeling production of the hull casting cannot meet the needs required, this project adopts low-pressure foundry techniques to improve the internal quantity of products.

The project of hole releasing adopted can form a protection shell with low earth stress and fuel gas pressure around the shaft, and the outburst was prevented effectively and economically.

Glass shell made of a light bulb to keep the filament in a vacuum, or inert gas under low pressure, role is to prevent oxidation of the filament at high temperature under.