3.3 根据阀门数据表的规定，阀球应采用转轴／枢轴形式安装。阀门的设计应能最大限度降低碎屑实际进入轴颈的可能。
3.4 阀座主要为金属与金属的接触。如果使用密封圈或其它密封件作不透水密封，则应将密封封装在相应的槽中，这样，密封就不会被座圈移动，在最大差压情况下，进行打开或关闭操作时，密封圈也不会被挤出密封槽。座圈的设计应能保证低压以及高差压时的密封。使用PTFE的阀座设计不被接受。
3.5 阀门应具有双阻塞和泄放功能，以便于对阀体腔进行彻底的冲洗、排放和排气。
 对于在液体条件下使用的阀门，应使用自动泄压座圈／装置，防止阀体腔中产生过压。禁止在阀球上留有压力释放孔。在阀体腔中的差压值不超过阀门额定压力的50％时，自动泄压座圈可以自动泄压。
3.6 当阀门数据表做出了规定时，在打开和关闭的位置，阀门的设计应能承受至少1（一）毫巴的持续内部真空压力。
3.7 额定尺寸在200mm（8’’）和以上尺寸的全径阀门和额定尺寸在250mm（10’’）和以上尺寸的缩径阀门，应提供在满管压力下二次注入密封剂的装置，以便对阀座和阀杆进行密封。密封剂注入点应提供装配了润滑脂加油嘴的针阀。密封剂注入点的位置和布局应如图－1所示。
3.8 阀门应提供排气和排放连管。与阀门一起提供的排气和排放连管的位置和布局如图－1所示。

3.3 Ball mounting shall be trunnion / pivot type as indicated in Valve Data Sheet. Valve design shall minimize the possibility of debris ingress into the trunnion as far as practicable.
3.4 Valve seats shall be with primary metal to metal contact. O-rings or other seals, if used for drip tight sealing, shall be encased in a suitable groove in such a manner that it cannot be removed from seat ring and there is no extrusion during opening or closing operation at maximum differential pressure. The seat rings shall be so designed as to ensure sealing at low as well as high differential pressures. Seat design with PTFE insert is not acceptable.
3.5 Valves shall have double block and bleed feature to facilitate complete flushing, draining
and venting of the valve body cavity.
For valves to be used in liquid service, the body cavity over-pressure shall be prevented by self-relieving seat rings / assemblies. A pressure relief hole in the ball is not permitted. Self-relieving seat rings shall relieve at a body cavity differential pressure not exceeding 50% of the valve class rating pressure.
3.6 When specified in Valve Data Sheet, valves shall be designed to withstand a sustained internal vacuum of atleast 1 (one) milli-bar in both open and closed positions.
3.7 Full Bore Valves of nominal size 200mm (8") and above and Reduced Bore Valves of nominal size 250mm (10") and above shall have provision for secondary sealant injection under full line pressure for seat and stem seals. Sealant injection points shall be provided with a needle valve accommodating a grease fitting. Location and arrangement of sealant points shall be as per Figure-1.
3.8 Valves shall be provided with vent and drain connections. Location and arrangements of vents and drains along with provision of valves shall be as per Figure-1.