At present, the stem seals of low-temperature stainless steel stop valves include stuffing box and bellows. Among them, the valve stem of mass-produced air separation devices mostly adopts stuffing box sealing structure. For valves working in toxic, flammable and explosive gas medium, the valve stem can be sealed with wave tube. However, in high-pressure gas greater than or equal to 80MPa, the bellows can not bear such high external pressure, so the stuffing box seal can only be used. The stuffing box seal is widely used in actual production because of its simple manufacturing and processing and convenient maintenance.

良工阀门

Lianggong valve

但是为保证填料的密性能,其工作温度一般不能低于-40℃,这就要求低温阀门上工作的填料函装置应尽量在接近环境温下工作。通常情况下,填料不结霜即认为其处于正的工作状态,但如果由于填料本身或工作寿命的原使填料不密封,则低温气体通过填料就会造成泄漏并使填料函冷冻结霜,又会造成填料的进一步泄漏失效。

However, in order to ensure the tightness of the packing, its working temperature shall not be lower than - 40 ℃, which requires that the stuffing box device working on the low-temperature valve shall work as close to the ambient temperature as possible. Under normal circumstances, the packing is considered to be in a positive working state if it does not frost. However, if the packing is not sealed due to the original of the packing itself or service life, the low-temperature gas will cause leakage through the packing and freeze the stuffing box, which will also cause further leakage and failure of the packing.

在航天领域应用的很多低温阀门系列中,由于成原因大多采用了填料函密封结构,而为了确保阀杆填料函的温度,均采用了加长阀杆长度的方法,所造成这些低温阀的尺寸均比较大。

In many low-temperature valve series applied in the aerospace field, the stuffing box sealing structure is mostly adopted due to the reasons. In order to ensure the temperature of the valve stem stuffing box, the method of lengthening the valve stem length is adopted, resulting in the relatively large size of these low-temperature valves.

低温不锈钢截止阀多用于介质不允许微量泄漏和不适填料的场合。在波纹管的设计中,其寿命是关键,波纹管的寿命与其行程大小和初始安装状态有关。

Low temperature stainless steel stop valves are mostly used in occasions where the medium does not allow micro leakage and unsuitable packing. In the design of bellows, its service life is the key. The service life of bellows is related to its stroke size and initial installation state.

良工阀门

Lianggong valve

保证波纹管截止阀的使用寿命,在行程一定的情况下,安装波纹时要保证其不承受附加外力的作用;在工作状态下由于波纹管承受的是外压,其工作状态较好,但由低温阀门的快速关闭或管道中可能存在的气穴都可能引水击。因此在波纹管承受的计算压力时,要加上定的系数,并尽可能使波纹管避免直接承受水击。

Ensure the service life of the bellows stop valve. When the stroke is certain, ensure that it does not bear the effect of additional external force when installing the bellows; In the working state, because the bellows bears external pressure, its working state is good, but water hammer may be caused by the rapid closing of low-temperature valve or possible cavitation in the pipeline. Therefore, when calculating the pressure borne by the bellows, a certain safety factor shall be added, and the bellows shall avoid directly bearing water hammer as far as possible.