The dynamic seal of the sealing ring is relatively prone to leakage for the following reasons:
Wear caused by relative motion: Dynamic sealing involves two components in relative motion, and there is continuous friction between the sealing surfaces. For instance, in the sealing of rotating shafts, as the shaft rotates, it constantly rubs against the sealing element. Long-term operation will cause wear of the sealing element, increase the sealing gap, and eventually lead to leakage.
The influence of temperature and pressure changes: During the operation of the equipment, temperature and pressure will change. An increase in temperature will cause the sealing material to expand or soften, and pressure fluctuations will exert different forces on the sealing parts. In high-temperature and high-pressure chemical equipment, the dynamic sealing parts are affected by drastic temperature and pressure changes. The sealing elements may deform or be damaged due to uneven thermal expansion or pressure shock, resulting in leakage.
Vibration and shock: Vibration and shock may occur during the operation of the equipment. These dynamic factors can cause damage to the dynamic seal. For instance, in a car engine, the rotation of the crankshaft generates vibration. If the installation of the dynamic sealing parts is not firm or the anti-vibration performance of the sealing parts themselves is poor, they are prone to loosening and damage under the action of vibration, thereby causing leakage.
Problems of the sealing ring itself:
Installation issues: Cutting or scratching the sealing ring during installation, poor welding and surfacing quality between the sealing ring and the body, loose connection threads, screws and pressure rings of the sealing ring, and corrosion at the connection points of the sealing ring, etc., may all lead to dynamic seal leakage. For instance, when installing PTFE seals, if you strike them with a hammer or pry them hard with a screwdriver as you would with rubber gaskets, grooves will be scratched on the sealing surface, leading to leakage.
Mismatch between material and working conditions: If the material of the sealing ring is incompatible with the medium, it will cause the sealing ring to deteriorate and fail. If the stretching or compression is inappropriate, it will cause the sealing ring to undergo permanent deformation and fail, or the contact stress will be insufficient, resulting in leakage. For instance, when seals made of NBR material are used under high-temperature conditions, the deterioration of the sealing ring due to heat can cause leakage.
Seal ring damage: During reciprocating motion, the O-ring may twist, which usually occurs in the initial stage of use. Twisting can cause the seal ring to break, leading to severe leakage.