1.related components factors

-less pressure in installation

-each bolt tighten unequally

-possible bolt damage

-incorrect bolt usage

-flange surface sub-calibration

2.gasket material factors

-re-installation of used gasket

-incompatibility with the operating medium

-inferiority to operating conditions

-improper jointing compounds usage

-off-size gasket

-high risk of leakage

3.designing factors

-insufficient force (bolt)

-over-exerted force
-improper usage of flange or bolt

4.flange factors

-possible damage flange