1.1 本规程涵盖了用于严重腐蚀应用的包络垫圈的设计、尺寸、分类和构造。外壳作为复合垫片的耐腐蚀构件，是非金属材料，如聚四氟乙烯、聚四氟乙烯或相关材料。插入件是非金属衬垫材料，有或没有金属加固。其他类型的复合垫片包含在分类中 F868 . 1.2 本标准直接基于ANSI B16.21-2011；因此，单位为ANSI规定的英寸。 1.3 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的用户有责任在使用前制定适当的安全和健康实践，并确定监管限制的适用性。 ====意义和用途====== 3.1 本规程涵盖的垫片可用于但不限于由以下材料制成的设备:( 一 )石器( b )玻璃和搪玻璃( c )钽（固体和衬里）( d )钛（实心、衬里或包层）( e )锆（固体和衬里或包层）( f )银色（实心和衬里），以及( g )镍和镍合金（固体和包覆）。 3.2 此处提供的垫片用于以下用途:( 一 )管法兰（平面或凸面）( b )容器喷嘴( c )容器中的圆形开口超过12英寸。（305 mm）直径，以及( d )容器中的椭圆形开口。

1.1 This practice covers the designs, sizes, classifications, and construction of enveloped gaskets for severe corrosive applications. The envelope serves as the corrosion resistant member of the composite gasket and is a nonmetallic material such as polytetrafluoroethylene, PTFE, or related materials. The inserts are nonmetallic gasketing materials with or without metal reinforcement. Other types of composite gaskets are covered in Classification F868 . 1.2 This standard is based directly upon ANSI B16.21–2011; for that reason units are as ANSI stated in inches. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. ====== Significance And Use ====== 3.1 The gaskets covered by this practice can be used on, but are not limited to, equipment constructed of the following materials: ( a ) stoneware, ( b ) glass and glass-lined, ( c ) tantalum (solid and lined), ( d ) titanium (solid and lined or clad), ( e ) zirconium (solid and lined or clad), ( f ) silver (solid and lined), and ( g ) nickel and nickel alloys (solid and clad). 3.2 The gaskets provided for herein are for the following: ( a ) pipe flanges (flat or raised face), ( b ) vessel nozzles, ( c ) circular openings in vessels in excess of 12 in. (305 mm) diameter, and ( d ) oval openings in vessels.