美国克雷恩系列21（平板）和系列23（吊耳）蝶阀和系列42和系列44蝶阀一样，贯彻“质量第一”的设计原则，除了工作压力为285 psi以外，其它主要特性都相同，包括：酚醛制成的衬套阀座，精密准确的阀板轮廓，整体轴杆，四个轴支撑轴承。系列21和系列23重型蝶阀适用于当今许多管道系统中条件比较恶劣的、高压使用环境中。由于全衬里阀体与流体介质完全隔离，因此蝶板和锥销就不需要采用太多昂贵的合金材料。
　　Crane Series 21 (wafer) and 23 (lug) valves utilize the same proven design features as our Series 42 and 44 valves but are rated to 285 psi. These design features include a phenolic-backed cartridge seat, precision profile disc, onepiece shaft, and four shaft support bearings. Series 21 and 23 heavy-duty butterfly valves are designed for the hostile operating conditions and high pressures encountered in many piping systems today. With the fully-lined body isolated from the flow stream, the use of expensive alloys is limited to the disc and taper pins..

　　(1) 双D阀杆结构：非常适用于连接操作手柄或执行机构。
　　(1) Double D Stem Configuration: Gives positive attachment for handles or actuators.
　　(2) 轴保护密封：（在某些型号上，轴保护密封位于衬套下方。）
　　(2) Shaft Weather Seal: (Below bushing on some models.)
　　(3) ISO 5211执行机构法兰：适用于各种类型的执行机构：手柄，齿轮操作机构，电动执行机构和气动执行机构。
　　(3) ISO 5211 Actuator Flange: Accommodates all types of actuators: handles, gear operators, electric actuators, and pneumatic actuators.
　　(4) 一体化贯穿轴：确保阀门的强度、可靠性合阀板的精确定位。
　　(4) One-Piece Thru Shaft: Ensures dependability and positive disc positioning.
　　(5) 衬套（4）：在三个位置上配置轴支撑，有利于轴校直和执行机构的支撑。
　　(5) Bushings (4): Furnishes shaft support at three locations for positive shaft alignment and actuator support.
　　(6) O-环：有助于防止轴泄漏。
　　(6) O-Ring: Helps prevent stem leakage.
　　(7) 阀座表面：不需要使用阀兰垫圈。
　　(7) Seat Face: Negates need for flange gaskets.
　　(8) 光滑表面的阀板：这些阀板上的“配套”使得密封非常有效，防止泄漏到轴区域内。
　　(8) Smooth Finished Disc Flats: These “mate” with seat flats to give a highly efficient seal; prevents leakage into shaft areas.
　　(9) 精密准确的锥形销钉：增强防震保护，强化轴与蝶板的结合。可在现场更换。
　　(9) Precision Taper Pin: Ensure positive, vibration proof, shaft to disc connection. Field replaceable.
　　(10) 精密准确的蝶板轮廓：防止“泡紧”关闭困难，确保最大程度见效扭矩，延长阀座寿命。
　　(10) Precision Profile Disc: Provides bubble-tight shut-off and assures minimum torque and longer seat life.
　　(11) 酚醛背衬阀座：不可拆解，抗拉伸，抗撞击。现场可更换。
　　(11) Phenolic Backed Seat: Non-collapsible, stretch resistant, blow out proof, field replaceable.
　　(12) 支撑性轴密封：弹性材料与酚醛背衬环的紧密结合体，有效防止由于扭曲变形导致的轴泄漏。
　　(12) Supported Shaft Seal: Bonding of elastomer to phenolic backing ring protects against distortion, a common cause of shaft leakage.