Cylinder common problems and causes analysis

1. The cylinder is cast, and the cylinder is subjected to aging treatment after leaving the factory, so that the internal stress generated by the cylinder during the casting process is completely eliminated. If the aging time is short, the machined cylinder will be deformed in the future.

2. The condition of the cylinder during the operation is very complicated. In addition to the static pressure of the gas inside and outside the cylinder and the weight of each component installed therein, it is also subject to the reaction force of the static part when the steam flows out of the vane. And the force of the various connecting pipes in the hot and cold state of the cylinder, under the interaction of these forces, the cylinder is prone to plastic deformation and leakage.

3. The load increase and decrease of the cylinder is too fast, especially the rapid start, stop and change of working conditions, the temperature change is large, the way of warming the cylinder is not correct, the insulation layer is opened too early during the maintenance, etc., in the cylinder and the flange Produces great thermal stress and thermal deformation.

4. The cylinder generates stress during the machining process or after repair welding, but the cylinder is not tempered to eliminate the cylinder, resulting in large residual stress in the cylinder, resulting in permanent deformation during operation.

5. During the installation or overhaul process, due to the maintenance process and maintenance technology, the expansion gap of the inner cylinder, the cylinder partition, the diaphragm sleeve and the steam envelope is not suitable, or the expansion gap of the hanger pressure plate is not suitable. After the operation, a large expansion force is generated to deform the cylinder.

6. The cylinder sealant used is of poor quality, too many impurities or the wrong type; if there are hard impurity particles in the cylinder sealant, the sealing surface is difficult to be tightly combined.

7. The clamping force of the cylinder bolt is insufficient or the material of the bolt is unqualified. The tightness of the cylinder joint surface is mainly achieved by the tightening force of the bolt. The thermal stress and high temperature generated when the unit starts or stops or increases or decreases the load will cause the stress relaxation of the bolt. If the stress is insufficient, the pre-tightening force of the bolt will gradually decrease. If the bolt material of the cylinder is not good, the bolt will be elongated under the action of thermal stress and cylinder expansion force during long-term operation, plastic deformation or fracture will occur, and the tightening force will be insufficient, causing leakage of the cylinder.

8. The order of cylinder bolt tightening is incorrect. Generally, the cylinder bolts are fastened from the middle to the two sides when tightening, that is, from the maximum position of the vertical arc or the place where the force is deformed the most, so that the gap at the maximum deformation is free to the front and rear of the cylinder. The end shifts and the gap gradually disappears. If it is tight from the two sides to the middle, the gap will be concentrated in the middle, and the cylinder joint surface will form a bow-shaped gap, causing steam leakage.