Tank Connectors are basically a type of tank fitting which is also known as Tank Inlet or may be called tank outlet or bulkheads. This fitting must be leakage proof as the water supply (Inward and Outward) depends on the same. There exist many different varieties of Tank Connectors, This variation is of its design which is different for different type of applications. More Information can be found on ANAYA EXPORTS± and Plastic Pipe Shop
Tank Connectors are widely made of Plastic (PVC) or Brass, in many continents this connectors are also known as tank nipple as it has male threads, Tank connectors have a flange either on the edge of one side or in center to be jammed with tank wall, This connectors are also supplemented with rubber washer and sometime plastic washer with hexagonal flange nut, to tighten the connector with the tank wall. The size range of the connector varies from 1/2" to 4", or the equivalent metric sizes, the size is denoted in the internal diameter of the connectors.
Tank connectors typically have a flange and a nut, although some have two nuts. Those with two nuts usually require some silicone or other sealant to prevent fluid passing along the threads.
Video Tank Connectors
References
Source of article : Wikipedia