Treatment method for deformation and leakage of cylinder joint surface

The reasons for the deformation and leakage of the cylinder joint surface are different, and the parts and the degree of the deformation and leakage are not different. ## Use a long flat ruler and a feeler gauge to check the deformation of the cylinder joint surface. In the maintenance, it should be based on the cause of the leakage. And the degree of deformation to take corresponding maintenance measures. The specific method is as follows:

1. The joint surface of the cylinder with large deformation or serious steam leakage should be scraped by grinding the joint surface. If the deformation of the upper cylinder joint surface is within 0.05mm, the upper cylinder joint surface is the reference surface, and the lower cylinder joint surface is coated with red lead or embossed blue paper, and the lower cylinder is scraped according to the traces. If the joint surface of the upper vat has a large deformation, apply red pill on the upper vat, grind out the traces with a large flat ruler, and grind the upper vat flat. Or take the mechanical processing method to level the joint surface of the upper cylinder, and then scrape the joint surface of the lower cylinder based on the upper cylinder. There are generally two methods for grinding and scraping the joint surface of the cylinder:

(1) It is a bolt that does not tighten the joint surface. Use a jack to slightly push the upper cylinder back and forth, and scrape it according to the coloring of the red lead on the joint surface of the lower cylinder. This method is suitable for high-pressure cylinders with strong structural rigidity.

(2) It is the bolt of the tight joint surface. According to the tightness of the joint surface of the feeler gauge, the value and the traces are measured, and the joint surface is repaired. This method can eliminate the influence of the vertical arc of the cylinder on the clearance.

2. Use proper cylinder sealing materials. Because there is no unified ## standard and industry standard for steam turbine cylinder sealants, the raw materials and formulas are also different, and the product quality is uneven; when choosing steam turbine cylinder sealants, it is necessary to choose products that have a reputation in the industry. A regular manufacturer with ## quality can use ## to overhaul the tightness of the cylinder.

3. The method of partial repair welding. As the joint surface of the cylinder is scoured or corroded by steam, the groove marks should be flattened by using a suitable welding rod, and the traces should be grind out with a flat plate or a flat ruler, and the weld bead and the joint surface should be scratched in the same plane. When the cylinder joint surface is deformed or the steam leakage is serious, repair one or two 10-20mm wide sealing tapes to eliminate the gap on the joint surface of the lower cylinder, then measure with a flat ruler or buckle the cylinder, and apply red pill to scratch. Until the gap is eliminated. The process of this operation is also very simple, preheat the cylinder to 150°C before welding, and then perform segmented desoldering or skip welding at room temperature. Choose austenitic electrodes, such as A407, A412, and cover with asbestos cloth after welding for heat preservation and slow cooling. After cooling to room temperature, perform grinding and scraping.

4. Coating or spraying of the joint surface of the cylinder. When there is a large area of ​​steam leakage on the cylinder joint surface, and the gap is about 0.50mm, in order to reduce the workload of grinding and scraping, the process of coating can be used. Use the cylinder as the anode and the coating tool as the cathode. Repeatedly apply the electrolytic solution on the joint surface of the cylinder. The thickness of the coating depends on the gap between the joint surfaces of the cylinder. The type of coating depends on the material of the cylinder and the type of repair. Depending on the process. Spraying is to use a special high-temperature flame spray gun to heat the metal powder to melt or reach a plastic state and spray it on the surface of the treated cylinder to form a coating with the required performance. Its characteristics are simple equipment, convenient operation and firm coating. The temperature of the cylinder after spraying is only 70°C-80°C without causing deformation of the cylinder, and a heat-resistant, wear-resistant and corrosion-resistant coating can be obtained. Note that the surface of the cylinder must be polished, degreasing, and napped before coating and spraying, and the coating must be scraped after coating and spraying. ##The bonding surface must be tight.

5. The method of mating the bonding surface. If the local gap leakage of the joint surface is not very large, 80-100 mesh copper mesh can be used to reduce the hardness by heat treatment, and then cut into an appropriate shape, spread on the joint surface where the steam leaks, and then match the cylinder sealant. If the gap between the joint surfaces is large and the leakage is serious, a groove with a width of 50mm and a depth of 5mm can be opened on the upper and lower joint surfaces, with a toothed pad of Igr18Ni9Ti embedded in the middle. The thickness of the toothed pad is generally about 0.05—0.08mm larger than the depth of the groove, and It can be adjusted with stainless steel gaskets of the same shape.

6. Methods of controlling bolt stress. If the deformation of the cylinder joint surface is small and uniform, new bolts can be replaced where there is a gap, or the pre-tightening force of the bolts can be increased appropriately. Tighten the bolts from the middle to both sides at the same time, that is, tighten the bolts from the vertical arc ## or the place where the force is deformed ##. The pre-tightening force of the control bolt can be calculated by the formula d/L≤A, where d is the ## gap on the outer edge of the facet of the flange, the unit is mm, L is the opening degree of the flange, the unit is mm, and A is A constant of the cylinder is related to the allowable ## stress of the bolt, the outer diameter of the bolt at the opening section, the moment of inertia of the flange ##, the elastic touch of the flange, the structure of the cylinder and the bending resistance of the flange. The data and measurement methods are still under study, and they have not been promoted at present. Most of them are within the allowable ## stress of the bolt, which is determined based on experience.

The tightness of the cylinder joint surface directly affects the safe and economical operation of the unit. It is an important job for the cylinder to inspect and repair the joint surface of the cylinder by repairing and scraping the joint surface of the cylinder to make it tight. In the process of dealing with the steam leakage of the joint surface, carefully analyze the cause of formation. According to the degree of deformation and the size of the gap, various methods can be used comprehensively to meet the strict requirements of the joint surface.