Operational techniques for eliminating leaks from flange gaskets

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Operation techniques for eliminating leaks from flange gaskets: There are many different types of flange clamps available, and the appropriate type can be chosen depending on the location of the leak. 1. Ordinary fixture sealing method (suitable for flanges with a gap of more than 6 mm) 1) Install the fixture: (1) Attach injection valves to all injection holes and tighten them so that they remain in the open position. (2) Ensure at least one injection hole is present near the leakage hole. (3) The edge of the small hole on the inner side of the injection hole should be close to the edge of the flange screw hole. (4) Minimize the clearance between the adjusting fixture and the flange circumference. (5) Tighten the fixture and check the planar gap between the two halves of the fixture; an ideal value is below 3 mm. The fixture can be tightened by using thin shims. If the flat gap is more than 6 mm, the fixture itself and the relevant surfaces of the flanges should be inspected to identify the cause, and appropriate measures or repairs should be carried out to meet the aforementioned requirements. 2) Inserting packing: Use packing (of a size larger or smaller than the gap between the flanges) and, with the help of a small hammer, gradually insert it into the flange gap, ensuring that the overlap at each end is at least 50 mm. A gasket with a smaller cross-sectional size can also be wrapped several times around the gap at the flange and tightened. 3) Inject sealant into the screw hole joint; use the \"0° operation method\" or the \"intermediate operation method\" to inject the sealant in order to eliminate leaks. Once the leakage is stopped, the screw hole joint can be removed. 2. Special methods for sealing leaks in male-female flanges and tenon-mortise flanges: Drill holes of φ3–φ4 mm near the leak site on male-female or tenon-mortise flanges, reaching straight into the groove, and then inject sealant using a G-type clamp or a specialized injection fixture to eliminate the leak. The key to this method is that the drilled injection hole must be aligned with the leakage point in the groove. 3. Local sealing method (used for large-diameter flanges with low pressure): A fixing clamp is used to apply sealant locally throughout the area. This method is adopted because it makes it easier to address any leaks that may occur in other areas once the leak point on this flange has been fixed. Install fixing clamps and add baffles on both sides of the leak site to prevent the sealant injected from overflowing out of the local sealing chamber. The baffle is supported by bolts, inserted into these bolts; its upper part is fitted into the groove of the fixture and secured with bolts, while its lower part extends up to the flange protrusion and the gasket, with a width equal to the gap between the flanges. After adjusting the gap, inject the sealant using the \"middle operation method\" to eliminate leaks. 2) Local fixture: The cross-section of the fixture is convex, with gasket grooves on both sides; sealant is injected to compress the gaskets. The width of the clamp should cover the outer circumference of the flange, and its circumferential length must be sufficient to cover a small sector on each side of the leakage point (the space between the two bolts). The fixture is secured by ring bolts on the flange bolts, and each small sector must have at least 1 injection hole. Inject the sealant using the \"intermediate operation method\" to eliminate leaks. 4. Full-seal method with flange (used for leaks caused by defects around the flange and leaks in flanges with gasket inserts) 1) Use the fixture specified in the pipeline design. 2) Wind packing or wire around the gap at the flange to prevent sealant from entering that gap. 3) Use the “0° operation method” to inject sealant to eliminate leaks. 5. Weld (inset) soft lead flange fixture (suitable for low temperatures and pressures, with gaps at the flange area)