Common problems and effective solutions to ensure flange integrity

Flanges, vital components in pipeline systems, play a crucial role in maintaining a secure and tight connection. However, several factors can lead to imperfect connections, compromising the integrity of the entire system. Here, we delve into the reasons behind loose flange connections and propose effective solutions.
Common Reasons for Loose Flange Connections:

Non-Parallel Sealing Faces:

The sealing faces of the connected flanges are not parallel, leading to uneven pressure distribution and potential leaks.

Defects in Sealing Faces:

Imperfections on the sealing faces of the flanges can result in gaps, undermining the tightness of the connection.

flanged steel pipe

Lack of Secondary Tightening of Flange Bolts:

Flange bolts may not undergo secondary tightening after the pipeline is put into operation, causing gradual loosening over time.

Gasket Failure:

Inappropriate material selection for gaskets or the use of excessively thick gaskets can lead to punctures under high-pressure conditions.

Gaskets may develop wrinkles, cracks, or fractures over extended usage, compromising their effectiveness.

Failure to Re-Tighten Flange Bolts After Operation:

Neglecting to perform a secondary tightening of flange bolts after the pipeline has been operational can result in gradual loosening.

ASME B16.21 Flange Gasket

Effective Methods for Eliminating Flange Connection Issues:

Hot Bending of Pipes on One Side of the Flange:

Apply an oxyacetylene flame to heat a strip-shaped area on one side of the pipe, with a length three times the diameter and a width not exceeding half the radius.

Bend the pipe to ensure parallel sealing faces on both flanges.

Machining Surface Defects:

Process shallow pits, radial scratches, or other defects on a lathe.

For defects deeper than 1mm, weld repair the surface after cleaning, followed by hand filing, scraping, or grinding for a smooth finish.

Periodic Re-Tightening of Bolts:

After the pipeline has been in operation, when temperature and pressure reach specific levels, perform a controlled re-tightening of bolts.

Regularly inspect bolt tightness during the initial days of operation.

Gasket Replacement:

Select gasket materials based on the type of medium and pressure.

Ensure gasket thickness complies with specifications.

Use high-quality gaskets during modifications.

Implement routine gasket replacements.

Regular Inspection and Re-Tightening of Bolts:

After the pipeline has been in operation, when temperature and pressure reach specific levels, re-tighten bolts appropriately.

Conduct frequent inspections of bolt tightness during the initial days of operation.

By addressing these issues and implementing effective solutions, the reliability and integrity of flange connections can be ensured, contributing to the overall safety and efficiency of pipeline systems.