gluing PVC into running setup

[The Codfather]

During the extrusion process, a waxy layer is brought to the surface of the tube. The primer, dissolves this wax, so when I apply the glue, it is bonding the plastics together. On a non pressure application this step is not a big deal and is often skipped. On larger, high pressure application, the use of a primer is a must.
Although I wouldnt consider our tank a high pressure situation, we do have to take into acount head pressure that may be above the joint.
Just my 2 cents, been working around this stuff for the last 20 years or so...