Valve is a fluid system using a variety of master components, can be used to switch or master flow and conditioning and other functions, and from the simple truncation function, the valve seal in the machinery, its function is to avoid the medium, from its cavity body along the joint of parts, leakage or blocking internal materials into the interior, the sealing effect of the collar, components called seals or sealing structure, referred to as sealing, the two joint surfaces and sealing surface contact, sealing.
Valve sealing surface is the central part of the valve, it can be divided into several types of leakage, that is, the leakage of the sealing surface, the leak at the sealing ring connection, the leakage of the closed part of the fall off and the leakage of foreign objects embedded between the sealing surface.
common use of valves in pipelines and equipment is to cut off the circulation of the medium, therefore, the sealing of the exhaust valve is an important factor in the choice of leakage or not.
Leak detection method 1 of the sealing surface of the exhaust valve, the sealing surface grinding unevenly, can not form a tight line; 4, the sealing surface material selection is improper or did not choose the valve according to operating conditions, the sealing surface is prone to corrosion, erosion, wear, 5, welding and heat treatment did not follow the procedures, due to hard through the low production of wear, corrosion due to alloy element burnage, due to internal Defects such as cracks caused by too much stress; 6, surface-treated sealing surface peeling or too large grinding, loss of original performance; 7, sealing surface closed not strict or due to cold shrinkage after the closure of fine seams, resulting in corrosion phenomenon; 8, the cut-off valve as a throttle valve The pressure relief valve is used, the sealing surface is destroyed by erosion, 9, the valve has been to the full closing position to continue to apply excessive closing force, including incorrect use of long lever operation, the sealing surface is crushed, extruded deformation, 10, the sealing surface wear is too large and the phenomenon of dropping the line, That is, the sealing side can not be well closed, exhaust valve valve seal surface leakage prevention and elimination methods: 1, sealing surface grinding, research equipment, abrasives, sandpaper and other items should be selected reasonable grinding method to be accurate, after grinding should be colored review sealing surface should not be Indentation, cracks, scratches and other shortcomings; 2, the stem and closed parts should fit the design request, the top heart does not match the request, should be trim, the top center should have a certain activity gap, in particular, the valve stem shoulder and closed parts of the axial gap is not Less than 2 mm; 3, stem twists and turns should be straightened, valve stem, stem nut, closed part, seat after adjustment, they should be on a common axis; 4, when using a valve or changing the sealing surface, should be in line with the working conditions, sealing surface processing , its corrosion resistance, resistance, scratch resistance and other performance is better; 5, welding and thermal solution process should be defy compliance process and standard skills to request seal surface processing should be accepted without permission to have any impact on the use of shortcomings exist; 6, sealing surface appearance fire, nitride, seepage shed, Plating and other processes must be strictly in accordance with its procedures and standards of skill request, grinding seal surface immersion layer should not exceed one-third of the layer of coating and immersion layer damage significant, should be removed after coating and immersion layer from the new appearance of the solution.
the sealing surface of the exterior high-frequency broken fire can be repeatedly broken fire repair;
For low-temperature valves, some closed after cold shrinkage emerged fine seams, should be closed after the certain time after the closure of the time to close more than once; 8, for the valve for cutting off the valve, not allowed to use the throttle valve, pressure relief valve, closed parts should be in full open or full-off status plus fruit must be adjusted media flow and pressure, should be set alone throttle valve and pressure reduction valve; Should fit the "valve operation" section, valve closure force is appropriate, hand wheel diameter is less than 320 mm, only allow one person to operate, equal to or greater than 320 mm diameter hand wheel, permit two people to operate, or one person with the help of 500 mm or less lever operation;