The following specifications specify stainless steel for the rotating ring and nickel aluminum
bronze for the stationary ring. In special circumstances, it may be desirable to make the rotating
ring bronze and the stationary stainless steel. Centrifugal cast, single piece rings are preferable,
but on large rings, sand casting or ring rolled forging may be required. These specifications are
only provided as a guide. Specifications for new seal rings should be issued only after adequate
research and analysis has been performed.
Stationary seal ring.
Each seal ring shall be cast as one piece from nickel aluminum
bronze, copper alloy C95500 or copper alloy C95800. The seal rings shall be cast to
nominal size by sand casting in accordance with American Society for Testing
Materials (ASTM) B148 or centrifugally casting in accordance with ASTM B27l, or
they shall be cast to a smaller diameter with a thicker cross section and ring rolled
forged to the required larger diameter. Rings cast from C95500 shall be annealed
and tempered. Rings cast from C95800 shall be annealed. The heat treatment
procedure of the casting shall be submitted for approval and shall include the initial
annealing temperature range and cooling rate and the tempering temperature range
and cooling rate if applicable. If the contractor elects to ring roll forge after casting,
the procedure must be submitted for approval.
If the zing is to be supplied in sections, each section shall be cast or the ring may be
cast in one piece, finish machined, and cut into sections using the wire EDM process
or other method that removes no more than 0.010 inch of material per cut.
Rotating seal rings.
Each seal -ring shall be constructed of stainless steel of the
chromium nickel-alloy type, conforming to ASTM A 743 grade CF-8 or CF10SMnN
(Nitronic 60) if cast, or conforming to ASTM A 167 type 304L if fabricated. If cast,
the seal rings shall be cast to nominal size, or they shall be cast to a smaller diameter
with a thicker cross section and ring rolled forged to the required larger diameter.
Fabricated rings shall be rolled and welded with not more than two weld seams per
ring. Fabricated rings shall be stress relieved, and the stress relief procedure shall be
submitted for approval. Cast rings shall be heat treated, and the heat-treating
procedure shall be submitted for approval. If the contractor elects to ring roll forge
after casting, the procedure must be submitted for approval.