Online plugging method

The invention provides an online plugging method. The method comprises the following steps: 1) sketching an area capable of withstanding the melt pressure of electrowelding by using a leak point as the center; 2) prefabricating a steel plate, wherein the edge of the steel plate falls in the area capable of withstanding the melt pressure of electrowelding; 3) arranging two holes on the steel plate, wherein one hole is right facing the leak point and is welded with a first valve, and the other hole is arranged below the leak point and welded with a second valve; and connecting the second valve with a vent position of a spare steam line; 4) connecting a pumping hole of an aspirator with the first valve, and connecting a power gas port with a power steam device; 5) installing the steel to a leakage device, and evacuating the leak gas to a safe area; 6) welding the steel plate to the leakage device; and 7) after steel plate welding, closing the first valve and the second valve, removing the aspirator to complete plugging. The invention utilizes the principle of pumping for plugging, and inflammable fuel oil and gas are pumped to safe area for emission, so as to create a safe environment for plugging site, and avoid damage and explosion fire caused by long time contact with oil and gas of the plugging personnel.