Flange surface interface leakage
Thread Content
I’m currently working on a project involving a heat transfer oil system, and almost all of the flange sealing surfaces are leaking. The gaskets used are graphite-metal wound gaskets. What can be done if I don’t want to cut the flanges apart? The gasket has been replaced and the bolts have been tightened evenly, but there’s still leakage during pressure testing; there really is nothing else that can be done. No deformation was observed in the flanges either. What do you all suggest we do? (Our company isn’t responsible for the pipeline installation.)
1. Could it be that the flanges were not properly mated during pairing? If the flanges are not properly aligned, tightening the bolts alone is not enough. 2. Is the pressure rating of the flange appropriate?
Since the cause of the leak has not been identified, it’s obvious that it’s impossible to know how to deal with it. It is recommended to find out the cause of the leak; it could be the gasket or the flange sealing surface
This post was last edited by xlxuiin on 2011-8-16 at 12:14. Were no pressure tests or airtightness tests conducted before it was put into use? Such problems should be detected early. The problem is quite serious! In terms of design: The appropriateness of the flange selection depends crucially on whether the type of sealing surface matches that of the gasket. Installation aspect: Whether the perpendicularity between the flange and the pipe is satisfactory (i.e., the parallelism of each pair of flange sealing surfaces). Quality aspect: Check whether the flange manufacturing meets the standards. Is the quality of the gasket satisfactory?
1. Whether the gasket is compatible with the flange; if not, sealing will not be possible； Are the pressure ratings the same? If flanges rated at 300LB are sealed with gaskets rated at 150LB, the sealing surfaces will shift out of alignment. 2. Check whether there are any damages to the gasket and flange sealing surfaces, especially longitudinal scars. 3. It’s also not acceptable to tighten the bolts too much; likewise, it’s not acceptable if the washer gets compressed and loses its ability to rebound.
One more thing: are the two flanges installed parallel to each other?
Does most of them have leakage issues?
If the flange grade and gaskets are in order, and if hot oil is circulating, it’s possible that the stress compensation in the pipes is insufficient, resulting in high stresses that cause leakage at the flanges. It is advisable to have an expert conduct a stress analysis, followed by making modifications to the pipes to achieve natural stress compensation. Then it might not leak.
What is the temperature of the hot oil? Consider using flange heat tightening
If it’s a male-female flange, try measuring the height of the boss. If it doesn’t meet the standards, no gasket will help. Next, try sealing it with different wave-shaped gasket inserts; if that doesn’t work either, then the issue lies with the flange. Element analysis using spectral detection may reveal that the Mn and C contents do not meet the standards, and the hardness of the flange is insufficient. It cannot be used once it is leaked, unless the medium is water. It is recommended to replace it
Leaking already during pressure testing? What is the quality of the flanges and gaskets themselves? Is there any deformation during the welding process, or is the pressure too high? Is the design of the sealing surface not suitable for the pressure applied, and are the bolts too tight? My humble opinion.