In pipeline valve used in a wide variety, different structure, it is the most easily damaged pipeline fittings, maintenance for each valve, shall be carried out according to the concrete structure.

1: for the maintenance of body and cover body and cover is the most outside the valve closed shell, to bear the pressure of medium, the additional force when operation, other parts of valve weight, as well as the joint flange or thread tension. Body and cover request has the certain strength and stiffness, their damage is mainly medium corrosion, erosion and mechanical damage caused by local defects, when wall thinning is caused by corrosion or erosion, and affects their strength and stiffness, cannot repair, should be replaced.

Overhaul, the body and cover should be in the water pressure strength test, water, compressed air, kerosene or other medium to test its rigor. The defects of the body and bonnet generally adopt the method of repair welding, depending on the material selects the corresponding electrode and welding procedure. Before welding repair defective metal should be cleaned, still should inspect and repair after repair welding, and eliminating stress.