The integrity of the flange connection is very important for the pipeline system of conveying fluid. Whether it is the pipeline system for transporting chemical media (such as hydrocarbons) or the water supply pipeline, the leakage of flange connection will cause serious environmental and economic impact, and even may bring huge potential safety hazards. If flanges are exposed to a corrosive environment or polluted industrial atmosphere without protective measures, the corrosion rate will be very fast.

In addition, because of the complex geometry of the flange connection, it is easy to cause gap corrosion between two flange surfaces and galvanic corrosion between different metals, which will seriously damage the integrity of the pipeline system. This paper introduces several practical methods to solve flange corrosion.

In order to meet the harsh production needs and reduce sudden shutdown caused by leakage, effective monitoring and detection are essential. Usually, technicians are more concerned about the leakage between flange surfaces but neglect the protection of fasteners and pipeline exterior, which may cause extremely serious consequences in a harsh external environment. Insufficient external protection will accelerate and expand the damage of flanges and fasteners, accelerate the deterioration of the whole sealing system, and may quickly destroy the structural integrity of the system, resulting in seal failure.

Because the visual inspection of the sealing surface of the flange connection can only be carried out when the whole system shuts down, the inspection procedure should be as simple as possible, so the external corrosion should be eliminated first. If the machine can not be shut down, only ultrasonic technology can be used to detect it. When external corrosion is uncontrollable, the process will be more complex and accurate test results can not be obtained. Therefore, in order to monitor the whole system and provide effective and feasible quality control and maintenance procedures, external corrosion protection of flanges and fasteners is very important.