Hammer Unions in general have three parts, a male part, a female part and a nut part. The male parts of the unions are the external threaded portions that are welded to the end of a pipe that is connected to the tank wall. Hammer union nut is through which the pipe continues further leading to the huge o-ring thereby entering into the female part. Hammer adjustments are the most necessary parts. The nut that is threaded on the interior is hammered and tightened on to the female part. Unions have a locked up o-ring that is squeezed together into the “D” square cross section area thereby sealing the fluid pressures up to 150 psi in opposition to the external diameter of the connecting pipe in the hammer unions.