Seat rings are long to compensate for temperature fluctuations and are seal-welded. Seating faces are hardfaced with Stellite 6, ground and lapped to mirror finish.

• 阀座环较长，并且是密封焊接的，能够补偿温度波动。阀座面用钨铬钴合金6硬化，研磨和层叠为镜面光洁度。