Application of online leak sealing technology for valve leak repair

1.The form and causes of valve leakage.

a.)the cause of valve stuffing box leak.

During the operation of the valve, there is a relative movement between the stem and the packing, which includes rotation and axial movement. With the increase of the number of switches, the number of relative movement also increases, as well as temperature, pressure, fluid medium characteristics and other effects, valve packing is the most vulnerable part of leakage.

b.)the cause of valve gland leak.

There are many reasons for leakage of valve flange seal, seal gasket insufficient pressure, joint surface roughness, gasket deformation and mechanical vibration, bolt loss of preload, gasket aging and so on.

c.)the cause of valve body leak

The main reason is caused by forging or casting defects in valve production,such as sand holes, porosity, cracks, etc.Erosion and corrosion of fluid medium are also one of the main reasons.

2.Valve Online leak sealing Principles and advantages.

a.)The principle of online leak sealing is to install a special clamp at the leakage site and to form a sealing cavity between the special clamp and the leakage site,then use special injection tools to inject the sealing compounds into the sealing cavity,and fill the whole sealing cavity fully by compounds.Make the Extrusion pressure of compounds is balanced with the pressure of the leakage medium,create a new sealing structure to prevent leakage.

b.)The advantage of online leak sealing is:No need shutdown,No need pressure relief,Save a lot of energy and manpower,Greatly reduce social and economic losses.

3.Several common methods of online leak sealing for valve leaks.

a.)For a valve stuffing box with a wall thickness greater than 8 mm, firstly drill a hole on the wall,then a injection adapter can be installed directly on the wall of the stuffing box thru the drill hole.The sealing cavity is the valve stuffing box itself, and the sealants are injected into the valve stuffing box by tools to repair the valve leak.

b.)For the thinner wall of the valve stuffing box, auxiliary clamp can be used.The auxiliary clamp is designed to make up for insufficient wall thickness.It is equivalent to a special joint part on the outer wall of stuffing box.Then drill a hole on the clamp and through the wall to inject sealants into the stuffing box,to repair the leak.

c.)For valve gland leak,if the leaking pressure is higher than 20 bar,we can use flange clamp method;if the pressure is low and the gaps between two flanges are less than 8mm,we can use steel strip banding method with screw bolts adapters,sealants will be injected thru the bolts adapters.

d.)For valve body leak,if the leaking pressure is low,just weld a proper nut onto the leaking point,use the teflon tape to wrap the bolt first, then install the bolt into the nut, and put out the leaking point.If the leaking pressure is high,or a crack leak,firstly we choose a proper size steel sheet,open a big hole on the steel sheet body,install the suitable adapter into the hole,let the adapter open in order to relief eaking pressure,then weld the steel sheet to cover leaking point,the opened adapter must face to leaking point directly,after welding steel sheet,close the adapter to stop leak.