不应该使用金属衬垫。

Metal gaskets should not be used.

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根据用于管道法兰的美国非金属衬垫标准ANSI B16.21，需要能够延伸至法兰面边缘的全面衬垫。

Full face gaskets extending to the flange face edge as given in American Standard Non-Metal gaskets for Pipe Flanges ANSI B16.21 are required.

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阀门的优点：用金属横膈膜代替人造橡胶衬垫在阀门和阀杆的顶部机件处给予了这种阀门出众的泄漏完整性。

Valve Advantages: The replacement of elastomeric packings by metal diaphragms gives this valve superior leak integrity at the top works of the valve and stem.

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