Monolithic Isolating Joint (MIJ)
Definition - What does Monolithic Isolating Joint (MIJ) mean?
A monolithic isolation joint (MIJ) is a piece of structural equipment that provides electrical isolation between parts of a pipeline. Such joints appear in the form of a solid block, and can be a simple piece of equipment due to the fact that they have no moving parts and are delivered fully assembled and ready to operate. Monolithic isolation joints are prone to corrosion when made of metal.
Corrosionpedia explains Monolithic Isolating Joint (MIJ)
Monolithic isolation joints are preferred whenever possible.
They are typically installed aboveground or in a sunken pit (where safety regulations allow), or are buried when used for pipelines. When installed aboveground, some of the benefits they provide are easy visual, electrical and ultrasonic inspection capabilities.
Moreover, buried joints are less exposed to detrimental environmental elements or factors, damage and contamination of the product that is housed inside the pipeline. The installation of a monolithic isolating joint in a pit provides the added advantages of a corresponding buried joint. However, there is the added risk of fluid entrapment; therefore local regulations might prohibit installing monolithic isolation joints in a pit.