1、 Correct connection between flange and pipeline

Center alignment: Ensure that the center of the pipeline and flange are on the same horizontal line, which is the basis for ensuring uniform compression of the flange sealing surface.

Vertical installation: The sealing surface between the center of the pipeline and the flange should maintain a 90 degree vertical shape to avoid uneven stress on the sealing surface causing leakage.

Bolt position correspondence: The position of the flange bolts on the pipeline should be consistent to facilitate uniform tightening of the bolts.

2、 Selection and installation of gaskets

Gasket material: Select the appropriate gasket material based on the characteristics of the medium and working conditions. Common gasket materials include rubber sheets, rubber asbestos sheets, etc. They should have good flexibility and corrosion resistance.

Gasket size: The width and thickness of the gasket should meet the design requirements to ensure sufficient sealing area and sealing pressure. At the same time, the surface of the gasket should be flat, without scratches or damage.

Gasket installation: The gasket should be placed between the two flange sealing surfaces and ensure that its position is correct and there is no offset. Before tightening the bolt, check whether the gasket has completely covered the sealing surface.

3、 The tightening sequence and force of bolts

Number and sequence: Number the pre tightened bolts on the flange and tighten them in the order of cross or symmetrical cross. This method can ensure uniform force distribution on the bolts and avoid local over tightening or over loosening.

Step by step tightening: When tightening bolts, it should be done step by step. First, tighten to 30% of the installation target load, and then check whether the flange clearance is uniform; Then tighten to 70% load and check again; Finally tighten to 100% load and thoroughly inspect the tightening of all nuts.

Force control: Use appropriate wrenches and tools for operation to avoid excessive force causing damage to bolts or flanges. At the same time, it is necessary to ensure that the tightening force of each bolt is consistent to achieve the best sealing effect.

4、 Inspection and maintenance

After installation inspection: After the flange connection is completed, a comprehensive inspection should be carried out, including the tightening of bolts, the sealing of gaskets, and the smoothness of the flange sealing surface.

Regular maintenance: Regularly inspect and maintain flange connections, promptly identify and address potential issues such as loose bolts and aging gaskets.

In summary, by ensuring the correct connection between flanges and pipelines, selecting appropriate gaskets and installing them correctly, tightening bolts in the prescribed order and with the required force, and conducting regular inspections and maintenance, the tightness and sealing of national standard flange connections can be effectively ensured.