Gate valve is the main component of oil (gas) wellhead equipment. The common faults of several gate valves in use are as follows:
4. Leakage at valve seat or valve disc
Leakage at the valve seat or valve disc is the most common phenomenon in the installation or maintenance of gate valve. Generally, There are two types: one is leakage of sealing surface, the other is leakage of seat root. First of all, To check the accuracy of the sealing surface between the valve seat and the valve disc, The sealing surface should be grounded at least. If the accuracy is too rough, The sealing surface should be grinded again. Secondly, To check if there are pitting corrosion, indentation, sand hole, cracks and other defects on the sealing surface. If so, the valve disc or valve seat should be replaced
For the valve seat with pressure spring, the elasticity of the pressure spring should be checked to meet the requirements. If the elasticity is weakened, the pressure spring should be renewed. In addition, check whether the T-shaped connection between the valve disc and the valve stem is too loose, resulting in the inclination of the valve disc in the process of pressing. In this case, the valve plate should be removed and adjusted to the optimal size.
5. The hand wheel of valve could not be rotated flexibly
Prevention&solutions:
5.1 It is necessary to strictly control the force and measure, and not to twist hard
5.2 Improve the processing quality to meet the standard requirements.
5.3 Carefully operate, do not use strong force while close valve, and do not reach the top dead center while open the valve. After reaching the dead center, turn the hand wheel back for one or two turns to make the upper side of thread close, so as to prevent the medium from pushing the valve rod upward.
5.4 Check the lubrication regularly and keep it in normal condition.
5.5 Straighten or correct the stem nut.
5.6 Modify or update the stem nut to meet the standard specification.
5.7 Clean the dust and sand of the stem nut frequently to prevent rust.
5.8 The valve rod protection sleeve shall be added if gate valve installed outdoors.
5.9 It is better to use copper material for valve stem nut, and do not use the same material as the valve stem.
Post time: Nov-19-2020