译文:
1、防火功能及密封性
油气储运系统中的介质均为易燃、易爆品。防火是油气储运装置在设计和选用时重点关注的问题,其装置不仅要求密封性要好,而巨在现场发生火灾的情况下还要具备一定的密封性能。双密封导轨阀的密封形式均采用软、硬密封结合,其中包括阀瓣及端盖、底盘等结构。软密封可以保证在正常运行状态下零泄漏,当现场发生火灾时,软密封有可能遭到破坏,这时硬密封将起主密封作用,可防止介质大量泄漏。相比较而言,闸阀采用硬密封,防火功能较好,但密封性能不容易得到保证,长期使用难以保证零泄漏;球阀采用软密封,其使用寿命较长,但不具备防火功能。
2、具有在线维修功能
当阀瓣上的软密封因某种原因受损造成内漏或操纵器(执行机构)出现故障时,不必将阀门从管道上拆下便可进行更换或维修,操纵器的维修也可在管道不停压的状态下进行。而闸阀或球阀密封部分受损时,必须将阀门从管道上拆下才能进行维修或更换,甚至直接将阀门报废。
3、具有双关断及泄放功能
采用两个隔断阀(闸阀或球阀)来隔断介质,并在这两个隔断阀之间安装一排泄阀,当隔断阀发生内漏,所泄漏的介质将通过排泄阀出,这样就不会造成两种介质的掺混。若用双密封导轨阀,仅需一个阀就可实现上述功能,双密封导轨阀的底部有一排泄介质
4、具有中腔泄压功能
API6D规范规定“对于所有双密封的阀门,当在液体介质中使用时,必须具有压差泄放功能”,泄放的压差是因环境温度的变化而产生的。在常闭状态下,双密封阀门中腔压力会因温度升高而快速增加,该压差如不及时泄放,对阀门的操作将产生严重影响。手动操作的双密封导轨阀通常有以下两种泄压系统。
(1)手动泄压系统手动泄压系统通常为一安装在端盖上的针形阀。当介质为可以少量向大气中排泄的液体时,可以配备此种泄压系统
(2)差热式泄压系统差热式泄压系统是一种带有单向阀的管路系统。在该系统中,针形阀I常闭,针形阀常开。当介质为不可以向大气中排泄的液体时,需配备此种泄压系统(一般是向上游管道中泄压)。差热式泄压系统不需要人为控制只有在检测内漏时,才需要手动打开针形。
5、具有检验内漏功能
当普阀门处于关闭状态时,其密封效果的检测比较困难,而双密封导轨阀的检测则很容易,只要在关闭状态下打开泄压系统与端盖相连的针形阀即可,阀瓣若有内漏,介质就会通过针形阀流出。若介质不使于向大气排放,则可在针形阀上接一压力表,通过观察表压的变化来判断有无内漏
6、独特的管道减压功能
管道减压是储罐区管汇设计中需要重点考虑的问题,即当罐前阀关闭后,管网中仍然充满了介质:随着环境温度的升高,管网中介质的压力会迅速增大;当温差变化较大时,增加的压力会超过管道的承受能力,容易造成管道泄漏因此,管道应配备减压设备管道减压设计.在主切断阀的上、下游之间连接管道减压系统,该系统由两个截断阀(闸阀、球阀或截止阀)及这两个截断阀之间的一个减压阀组成该套系统成本高,而且占用空间,不方便现场管理。主切断阀选用双密封导轨阀的管道道设计原理,减压系统附在主切断阀上,其设计结构简单,占用空间小,且成本低廉。
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原文:
1, flame retardant and sealing Medium oil and gas storage and
transportation systems are flammable and explosive materials. Fire
is the oil and gas storage and transportation device when used in
the design and focus of concern, the device requires not only seal
better, but huge in the case of a fire scene should have a certain
sealing performance. Double seal valve guide seal the form of both
soft and hard seal combination, including the disc and cover, the
chassis structure. Soft seal ensures zero leakage under normal operation, when the fire scene, the soft seal may
be damaged, then seal will play the role of the main seal to
prevent leakage of media a lot. By comparison, the gate valve with
seal, fire prevention function better, but the sealing performance
is not easy to be guaranteed, long-term use is difficult to ensure
zero leakage; ball valve with soft seal, its long service life, but
do not have fire safety features. 2, with line maintenance
functions When the valve flap on the soft seal for any reason,
causing damage to the internal leakage or manipulator (executive
body) fails, without removing the valve from the pipeline can be
replaced or repaired, the maintenance of the manipulator can also
be pipe under constant pressure conditions. The sealed part of the
damaged gate or ball valve, the valve must be removed from the
pipeline to be repaired or replaced, or even directly to the valve
end of life. 3, with double-off and discharge function Using two
isolation valve (gate valve or ball valve) to cut off media, and in
between the two cut off valves installed a drain valve, internal
leakage occurs when the cut off valve, the media will leak out
through the drain valve, so no lead to mixing of two media. If the
guide rail with double seal valve, a valve can only achieve
these functions, double-sealing valve at the bottom rail has a
drainage medium 4, with pressure relief function in the cavity
API6D specification "for all dual-sealed valves, when used in a
liquid medium, it must have a pressure bleed function", relief of
the pressure difference is due to changes in ambient temperature
produced. In the normally closed state, the double sealed valve in
the cavity pressure due to rapid increase in temperature increases
the pressure if not vented, the valve will have a serious impact on
the operation. Manual operation of the double seal valve guides are
usually of two pressure relief system. (1) Manual pressure relief
system for a manual pressure relief systems are usually installed
in the end cap on the needle valve. When the medium can be a small
amount of discharge to the atmosphere when the liquid can be
equipped with such a pressure relief system (2) differential
thermal differential thermal pressure relief system pressure relief
system is a pipe system with one-way valve. In this system, I often
close the needle valve, needle valve is always open. When the
medium is not discharge into the atmosphere when the liquid is to
be equipped with such a pressure relief system (generally upstream
pipeline pressure relief). Differential thermal pressure relief
system does not require human control only within the leak
detection only when the need to manually open the needle. 5, with
the inspection function within the leakage When the S & P valve
is turned off, its seal testing difficult, and detection of
double-seal valve guide is very easy, just open the pressure relief
system off and end caps can be connected to the needle valve, valve
leakage within the valve if the medium will flow through the needle
valve. If the media not to discharge in the atmosphere, can be
connected in the needle valve on a pressure gauge, gauge pressure
by observing the changes to determine whether the endoleak 6, the
unique function of pipe decompression Pipeline manifold vacuum is
the design of storage tank area need to focus on consideration,
that is, when the tank before the valve closed, the pipe is still
full of the media: With the ambient temperature, medium pressure pipeline
network in the rapidly growing large; when larger temperature
changes, increasing the pressure will exceed the capacity of pipes,
easily lead to pipeline leakage, therefore, should be equipped with
vacuum equipment, pipe decompression pipeline design. in the main
shut-off valve, the downstream connection between the vacuum pipe
system, which consists of two cut-off valve (gate valve, ball valve
or stop valve), and between the two cut-off valve of a valve
component of the system cost, but also take up space, convenient
on-site management. Use the main shut-off valve pipe valve dual
seal guide channel design principles, vacuum system, attached to
the main cut off valve, its design is simple, small footprint and
low cost.
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