In industrial production, valves are critical components for fluid control, and their sealing performance directly impacts system safety and stability. Leakage not only reduces operational efficiency but may also lead to fluid escape, posing serious safety risks.

This article outlines three common causes of valve leakage and provides corresponding emergency response recommendations to help you quickly identify issues, take action, and mitigate risks.

1. Seal Surface Wear or Damage

Cause:

During long-term operation, sealing pairs (e.g., valve seat and disc, valve ball and seat) suffer from media erosion, particle abrasion, or corrosion, leading to uneven sealing surfaces and resulting in minor or significant leakage.

Emergency Measures:

· Minor Leakage: Adjust compression force (e.g., tighten bonnet bolts) to temporarily reduce leakage.

· Severe Leakage: Immediately shut down the system to replace or regrind sealing components; replace the entire valve if necessary.

Prevention Recommendations:

Conduct regular inspections, select valves with appropriate materials and wear-resistant designs. For media containing solid particles, use hard-sealing structures.

2. Packing Aging or Gland Loosening

Cause:

Valve stem sealing uses packing materials (e.g., graphite, PTFE), which may age, dry, or crack over prolonged use. Temperature fluctuations can also cause gland loosening, leading to leakage at the packing box.

 Emergency Measures:

· Tighten packing gland bolts to increase packing compression.

· If ineffective, add or replace packing material.

· Avoid over-tightening to prevent increased operating torque or stem damage.

Prevention Recommendations:

Regularly replace packing; select materials compatible with the media and operating temperature. For critical equipment, consider spring-loaded packing glands.

3. Casting Defects or Corrosion Perforation in Valve Body/Bonnet

Cause:

Some low-quality valves have casting defects such as sand holes or shrinkage cavities. Prolonged exposure to corrosive media can cause localized perforation of the valve body, resulting in uncontrollable leakage.

Emergency Measures:

· For small leaks, temporary repairs using metal adhesives or cold welding are possible.

· Large-scale damage requires immediate valve replacement.

· For high-pressure or toxic/hazardous media, no pressurized repair is allowed; follow shutdown procedures strictly.

 Prevention Recommendations:

Purchase valves from reputable manufacturers; use corrosion-resistant materials (e.g., 304/316L stainless steel). Perform regular wall thickness inspections on critical pipelines.

Common Questions & Answers (Q&A)

Q1: Can all valve leaks be fixed by replacing packing?
A: No. Packing replacement is effective only when leakage is due to packing aging or gland loosening. If the leakage stems from seal surface or valve body damage, other measures are required.

Q2: Is it possible to repair leaks under system pressure?
A: Only for low-pressure, non-hazardous media with controllable minor leaks, and performed by experienced personnel. For medium to high-pressure systems or hazardous media, shutdown is mandatory.

Q3: Are leaks in electric or pneumatic valves always caused by the valve body?
A: Not necessarily. Actuator issues such as sticking, inaccurate signals, or incomplete closure must be checked to avoid misdiagnosis.

Q4: How significant is the impact of valve leakage on the system?
A: The impact depends on the media type and pressure level. Even minor leaks can cause economic loss, equipment corrosion, or safety hazards over time and should not be ignored.

Q5: Are there valves that never leak?
A: According to standards, there is no “absolutely leak-proof” valve. Some high-end metal-seated ball valves or special-process butterfly valves can achieve “zero leakage” under certain conditions but require proper maintenance.

In Conclusion

Valve leakage is a common issue; however, most leaks can be prevented and promptly addressed through proper valve selection, standardized operation, and regular inspection. Enterprises should strengthen staff training and implement thorough valve inspection programs to ensure long-term system stability.

If you encounter valve leakage or other technical challenges during operation, please contact DERVOS expert engineers. We are committed to providing you with personalized technical support and tailored solutions.