Description of the static seal of the pressure reducing valve

Introduction to the static seal of the pressure reducing valve:
 
    During the operation of the pressure reducing valve, it was found that the oil inside the pressure regulating chamber of the pressure reducing valve was extravasated at the joint between the connecting sleeve and the valve body; during the process of disassembling the pressure reducing valve, the connection of the connecting sleeve was found. The solidified fastening glue on the thread forms a concave-convex surface, and the O-ring has been deformed to form a leakage passage, which seriously affects the sealing between the connecting sleeve and the valve body.
    1. Analysis of the sealing problem
    After analysis with relevant experts, it is found that the seal between the connecting sleeve of the pressure reducing valve and the valve body mainly relies on the O-ring between the connecting sleeve and the inner wall of the valve for circumferential sealing (see Fig. 1), the sealing Once effective, external leakage is inevitable. After checking and analyzing the disassembly of the leaking part, it is considered that the seal between the connecting sleeve and the valve body has the following problems.
    (1) The sealing surface of the valve body is not sealed. Since the connecting sleeve of the pressure reducing valve and the valve body mainly rely on the thread connection; in order to prevent the thread from loosening, when the pressure reducing valve is assembled, the fastening glue is applied on the external thread of the connecting sleeve, and the fastening glue overflows to the O-ring. On the ring sealing surface, the fastening rubber forms a rough surface on the sealing surface after solidification, forming a leakage passage, which makes the O-ring inner and outer seals not tight, leaving a hidden danger for oil leakage. Seals
    (2) The O-ring compression is low, causing the O-ring seal to fail. At present, the specification of the O-ring between the connecting sleeve and the valve body is φ31.47mm×φ1.78mm, the depth of the sealing groove is 1.6mm, and the compression ratio of the O-ring is 10.1%, which is much lower than the normal theoretical static sealing compression ratio. 15% to 30%, the sealing surface cannot be effectively sealed, resulting in seal failure.
    (3) Defects in the form of the seal itself. The seal between the pressure reducing valve connecting sleeve and the valve body is completely sealed in the circumferential direction by the circumferential compression of the O-ring. Although the sealing form is widely used, the assembly operation is strict. In the assembly, the O-ring and the circumferential sealing surface are required to remain vertical. Otherwise, the O-ring tends to become elliptical in the circumferential direction, which causes the O-ring and the sealing surface to be ineffective contact, and the final seal fails. After inspection of the O-ring, it was found that the outer circumference of the O-ring was scratched to form an oil extravasation passage.
    (4) The friction between the O-ring and the sealing surface is too large. Since the O-ring rotates along with the sealing surface during the installation process, since the hardness of the O-ring is relatively small with respect to the sealing surface, scratches are easily generated, thereby causing leakage.