Block Valve Self-sealing Ring

The block valve self-sealing ring is a key sealing component in high-temperature and high-pressure steam systems of boilers. It is used to prevent media leakage and accommodate deformations caused by thermal expansion and contraction. Its design must ensure long-term stability under extreme operating conditions.

Installation and Maintenance of Block Valve Self-sealing Ring

• Preparation before installation:
  • Clean the sealing surface: Ensure the sealing surfaces of the valve seat and valve core are free of scratches, rust, and oil stains. If necessary, polish them. The surface roughness should meet design requirements (usually Ra≤1.6μm).
  • Inspect the sealing ring: Check if the material and dimensions match the valve model. Inspect the ring for any cracks, deformation, or aging defects. For metal sealing rings, ensure there are no burrs on the surface.
• Installation requirements:
  • Avoid forced assembly: Handle the sealing ring gently during installation to prevent deformation from misalignment or collision. For metal rings, ensure they are concentric with the sealing surface.
  • Control pre-tightening force: Uniformly tighten the bolts according to the designed torque based on the ring’s material and operating conditions. Avoid over-tightening, which can cause plastic deformation and failure, or under-tightening, which can lead to initial poor sealing.
• Maintenance and replacement:
  • Regular inspection: During valve overhauls, inspect the sealing ring for wear, corrosion, or creep. If steam erosion marks or signs of leakage (such as scaling or discoloration) are found on the sealing surface, the ring must be replaced promptly.
  • Replacement cycle: Due to high-temperature and high-pressure conditions, the service life of the sealing ring is usually synchronized with the valve overhaul cycle (e.g., 1-3 years). In extreme conditions, the replacement cycle should be shortened to prevent leaks caused by aging failure.

Causes of Failure and Countermeasures
Self-sealing ring failure can lead to high-temperature and high-pressure steam leaks, causing equipment damage, energy waste, and even safety accidents.

• Material aging: Material properties degrade under long-term high temperatures (e.g., graphite embrittlement, metal creep). Select high-temperature resistant materials that match the operating conditions and regularly test material properties.
• Damaged sealing surface: Scratches or deformation of the sealing surface lead to poor fit. The sealing surface accuracy must be strictly checked before installation, and the valve seat/core should be repaired or replaced if necessary.
• Improper pre-tightening force: Under-tightening causes initial sealing failure, while over-tightening damages the sealing ring. Control the pre-tightening torque according to specifications and use a symmetrical tightening method.