The dirt on the cover of the trap, scratches, abrasions, protrusions, slag, and curved seat surfaces provide leakage paths or cause washers to compress unevenly, resulting in flange leaks. This is the result of no flange cover installed.
The stress of the bolt is not uniform. Incorrect fastening and assembly processes or difficulty in touching fasteners may loosen some bolts, while others are over-tightened, resulting in gasket crushing. This can lead to leakage during work, especially when heavy load bolts are loose during high-temperature work.
The flange is not properly aligned, especially if the flange surface is not parallel, resulting in uneven compression and local crushing of the washer, resulting in subsequent leaks. The incorrect alignment of the flange centerline can also lead to uneven gasket compression and flange leakage.
The pipeline system at the flange position is overburdened. Excessive force and bending can lead to loosening of bolts or distortion of the flange, resulting in leakage.
The above is why the flange will leak, which is enough to explain the important role of the flange protection cover, it can be very good to avoid the flange during the connection of some leaks and other damage to the human body protection. So when installing the flange, remember to install the cover.