During the operation of a steam turbine, air leakage from the cylinder is a common equipment issue. The rigidity of the cylinder mating surfaces directly affects the safety and operational performance of the unit. Therefore, inspecting and lapping the cylinder mating surfaces to ensure a tight seal is an essential task in cylinder maintenance. When addressing air leakage at the mating surfaces, it’s crucial to carefully analyze the underlying causes based on the degree of deformation and the size of the gap. Various methods can then be employed to meet the stringent requirements for the combined surfaces. Below is... Shandong Steam Turbine The manufacturer's relevant introduction.

1. A specialized manufacturer of steam turbines from Shandong points out that the cylinder is cast, and therefore must be stored in the factory for a certain period before being processed, allowing any internal stresses generated during the casting process to fully dissipate. If the storage period is too short, the machined cylinder will likely deform during future operation.
2. The steam turbine cylinder in Shandong faces complex conditions: there is a pressure difference between the inside and outside of the cylinder, as well as static loads due to the weight of various components installed within the equipment. Additionally, forces act on the cylinder under both cold and hot operating conditions. Under the combined effect of these forces, the cylinder’s plastic deformation is accelerated, ultimately leading to leakage.
3. Pay particular attention during equipment operation to factors such as excessively rapid changes in cylinder load, significant temperature fluctuations, improper cylinder warming procedures, and premature removal of insulation layers. Check whether thermal stresses and thermal deformations are present.
4. During the machining process, stresses are generated in the cylinder, or after welding, but no tempering treatment is performed to relieve these stresses, resulting in significant residual stresses within the cylinder that cause permanent deformation.
5. During the installation or major overhaul of steam turbines in Shandong, improper expansion clearances in the inner cylinder, cylinder diaphragms, diaphragm sleeves, and steam seal sleeves—due to maintenance procedures and technical factors—or improper expansion clearances in the lug and clamp plates can result in significant thermal expansion forces after operation, leading to deformation of the cylinder.
6. The cylinder sealant used is of poor quality, contains excessive impurities, or is the wrong model; the sealant for Shandong steam turbines is difficult to bond tightly with the sealing surface.
7. Insufficient tightening force of cylinder bolts or substandard bolt material can compromise the tightness of the cylinder joint surface, which relies primarily on the bolts' tightening force to maintain its integrity. Insufficient tightening force can lead to cylinder leakage.
8. The sequence of cylinder bolts is incorrect. Generally. Shandong Steam Turbine Tighten the cylinder bolts from the middle toward both sides. If tightened too tightly from both sides, the gap will concentrate in the middle, creating an arched gap at the cylinder mating surface and leading to steam leakage.