RJT is an acronym for Ring Joint Type. RJT unions are often referred to as a standard sanitary union. They comprise of a stepped seal which leaves a small crevice where the liner and male part of the union overlap. RJT unions are very popular for frequently dismantled sections of pipework. The Metal Company stock RJT union in sizes ½”, ¾” and 1¼” which are uncommon in New Zealand.