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.
采用钻孔释放方案，在井筒周围形成一个低地应力、低油气压力保护壳，能经济有效地预防突出。
3
Glass shell made of a light bulb to keep the filament in a vacuum, or inert gas under lowpressure, role is to prevent oxidation of the filament at high temperature under.