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|  MIL-P-18472G(SH)
Accessory parts such as vent petcocks and drain plugs shall be of the
material specified for the major part with a difference of 50 Bhn minimum if
subject to galling or be of a more noble material.
Detail drawings and lists of material shall reference the specification
followed in each case, and shall include the class, type, or grade of
material used in each case, as applicable.
Post weld heat treatment shall be required for repairs to areas in which
excavation depth of 20 percent of wall thickness, or 1 inch, whichever is
smaller is realized, or when total cavity area exceeds 2 square inches. Post
weld heat treatment is not required for other repairs except by agreement
between the contractor and the contracting agency.
The design of bolts, studs, and nuts shall be in accordance with MIL-S-1222.
Nickel-copper-aluminum alloy bar stock used for threaded fasteners shall be
as specified in MIL-S-1222.
Nickel-copper-aluminum alloy parts shall be annealed prior to age-hardening
except parts for which a hardness greater than 265 Bhn is required.
Special high lead bronze or other bearing materials may be used subject to
review by the design agency. Bearing metal, alloy B-10, is an acceptable
alternative material.
When the mechanical properties of the material used in the fabrication of a
part are altered by metal working processes or heat treatment, sample mate-
rial from each lot of material, as defined in the material specification,
shall be subjected to tensile tests in the final heat treated condition for
the part. As a minimum, tensile tests shall determine ultimate strength,
yield strength, percent reduction in area, percent elongation and hardness.
The tensile tests shall be conducted on test samples machined from the heat
treated material or from a piece of parent stock which had been heat treated
in the same batch in the lot processed at the same time. The tensile test
requirements and acceptance criteria for mechanical properties shall be
included on the part drawing. Acceptance criteria for the mechanical
properties shall be in accordance with the material specification or as
approved by the design review agency. In no case shall ductility of less
than 10 percent elongation in 2 inches be allowed. These requirements are
not applicable to heat treatment performed as the result of the weld repair.
A wearing ring and its opposing surface shall be of dissimilar material or
shall have a difference in hardness of at least 50 Bhn.
For vertical close-coupled pumps, where the entire weight of the assembled
unit is supported by the mounting bracket, steel may be used for the mate-
rial of the bracket provided it does not form a part of the pump casing and
provision is made for draining all pockets.
Cyclone separator parts exposed to water velocities greater than 15 feet per
second shall be made of nickel-copper alloy. Other cyclone separator parts
shall be 70-30 copper-nickel except: parts such as fittings, not readily
available in 70-30 copper-nickel, may be made of nickel-copper alloy and
parts that would be unacceptably galvanically attacked if made of 70-30
copper-nickel shall be made of nickel-copper alloy.
For close-coupled type units the pump shaft material shall be specified to
the motor manufacturer.
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