Why security pneumatic valve sealing surface damage

the seal on the pneumatic valve channel plays a truncation and connect, adjustment and allocation, separate and mix medium etc, so the sealing surface is often medium corrosion and erosion, wear, easy to damage.

the failure reasons of sealing surface for two kinds of damage and natural damage. Artificial damage, is due to the design and manufacture not jing, material selection and week, undeserved, factors such as lack of bad installation is not straight, use and maintenance. Natural damage, is a pneumatic valve under normal working condition of wear and tear, is medium corrosion and erosion of seal face the inevitable damage.

mechanical damage, sealing surface produces in the open and close a scratch, bruised, against damage. Between the sealing surface, under the action of high temperature and high pressure permeable leakage occurred atoms, produce adhesion phenomenon. When the two seal face each other while moving, adhesion pull to tear easily. Sealing surface coarse degree is higher, this kind of phenomenon occurs more easily. Pneumatic valve, pneumatic valve in the process of closed in the process of return will touch the wounded and squeeze sealing surface, make local sealing surface wear or indentation.
medium erosion, it is a medium activity on sealing surface wear, flushing, the results of the cavitation. Medium under a certain speed, variety of fine particle in medium resistance to break the seal face, make its local damage, high-speed medium directly flush seal face, make its local damage, medium mixed flow and partial vaporization, angry bubble production blasting shock sealing surface, cause local damage. Alternative action medium of erosion and chemical erosion, sealing surface erosion will be strong.
electrochemical erosion, sealing surface contact each other, the sealing surface contact with the enclosed body and pneumatic valve body and the concentration difference between the medium, and poor oxygen concentration, will generate an electrical potential difference, electrochemical etching, the anode side of the sealing surface erosion.
medium chemical erosion, sealing surface near the medium in the case of no current, medium directly with the sealing surface chemistry, erosion seal face.
installation is not lack of maintenance in operation of the sealing surface of pneumatic valve to operate, in spite of premature damage the sealing surface.
damage caused by improper selection and bad manipulation. Mainly manifested in not according to the working condition of the premise choose pneumatic valve, pneumatic valve when the truncated throttling use pneumatic valve, lead to too much closed pressure and closed too quickly or closed lax, the sealing surface by erosion and wear.
sealing surface machining quality is bad, mainly displays in the sealing surface defects such as cracks, porosity and clamp design, because of the overlaying welding and heat treatment specification improper selection and bad manipulation caused by overlaying welding and heat treatment process, sealing surface hard through the high or low, because of the differences caused by error or improper heat treatment, select material sealing surface hardness uneven, no corrosion, mainly because of the underlying metal in welding process blow to the above, to dilute the sealing surface of alloy composition. There are, of course, the topic of design.
the cause of damage of sealing surface, can be summarized as the following several kinds.
the failure reasons of sealing surface for two kinds of damage and natural damage. Artificial damage, because of bad design, the manufacture is not pure, improper material selection, installation, use caused by factors such as bad and lack of maintenance. Is a natural damage, the pneumatic valve under normal working condition of wear and tear, is the medium of seal face of the inevitable erosion and erosion damage.