Globe valve sealing performance is directly related to the service life of the valve, seal failure will not only lead to media leakage, but also may cause chain damage. The following from the impact of seal failure mechanism, typical damage patterns and engineering response measures to analyse:

First, the core mechanism of sealing performance impact life

1. Direct damage caused by media leakage

Internal leakage (valve and seat sealing surface leakage):

High-pressure media continue to wash the sealing surface, resulting in valve cone or seat sealing surface grooves, pits (such as steam pipelines, internal leakage will make the sealing surface due to high-speed cavitation and increased wear).

Containing particles of media (such as sewage, slurry) internal leakage, particles will be embedded in the sealing surface gap, exacerbating the wear and the formation of a vicious circle (each time the opening and closing of the particles squeeze the sealing surface, resulting in a gradual increase in the amount of leakage).

External leakage (stem packing box or bellows leakage):

Corrosive media leakage will corrode the surface of the valve stem, resulting in a larger gap between the packing and the valve stem, further increasing the leakage; high temperature media leakage may make the packing carbonisation failure (such as steam pipeline leakage resulting in asbestos packing hardening).

2. Indirect failure caused by seal failure

Abnormal vibration and scouring:

Internal leakage of the medium in the valve flap and seat gap to produce high-speed jet, triggering vibration of the valve body (especially in the high-pressure differential conditions), long-term vibration may lead to loosening of bolts, valve cracks or fatigue damage to the sealing surface.

Abnormal system conditions:

Such as boiler water supply globe valve leakage will lead to water level control failure, frequent opening and closing of the valve exacerbate the wear of the sealing surface; gas pipeline globe valve leakage may lead to safety hazards, and be forced to frequent maintenance to affect the life of the valve.

Second, the specific impact of sealing performance on the life of the scene

1. Seal failure under high-pressure conditions

Case: a petrochemical plant high-pressure hydrogenation pipeline (10MPa) globe valve due to defects in the sealing surface of the cladding layer caused by internal leakage, the medium of high-speed scouring of the sealing surface in 3 months, the depth of 1mm grooves, and ultimately the valve valve breakage failure.

Life impact: normal high-pressure globe valve (good seal) life of up to 5 ~ 8 years, while the seal failure life may be shortened to less than 1 year. 2.

2. corrosive media in the seal failure

Case: a chemical pipeline conveying 30% hydrochloric acid stainless steel globe valve, because the valve sealing surface is not surfaced with corrosion-resistant alloy (such as Hastelloy), 1 year after the sealing surface of the intergranular corrosion perforation, resulting in leakage of the medium.

Life impact: corrosion-resistant sealing surface design of the valve life of up to 3 ~ 5 years, ordinary material sealing surface in the strong corrosive media may only be able to use 1 year. 3.

3. high-frequency opening and closing of the seal wear caused by

Case: sewage treatment plant to regulate the flow of small-diameter globe valve (DN25), due to open and close more than 50 times a day, 6 months after the sealing surface due to fatigue wear and leakage, while the same conditions of the valve sealing design optimisation can be used for more than 2 years.

Yantai Valtone Valve Co., Ltd.

Email: 

liujun@valtone-valve.com

carrie@valtone-valve.com

Tel: 

+86-535-6391338
Cell Phone: 

+86-18660599666

Address:

No. 13, Wuhan street, Bajiao industry park, Yantai ETDZ, Shandong, China