3321Gray Iron Castings

3321.1SCOPE

Provide gray iron castings for drainage or structural use. The castings are classified according to tensile strength, but the Department will make provisions for acceptance of drainage castings and other ornamental or non-stress bearing castings on the basis of flexural tests.

3321.2REQUIREMENTS

Provide gray iron castings meeting the requirements of AASHTO M 105 Standard Specification for Gray Iron Castings, for the class required by the Contract. Obtain the castings from foundries, approved by the Materials Engineer, in accordance with these Specifications. A Class Designation If the Contract does not specify a strength class, provide castings in accordance with any of the following:

and sliding shoes

manhole castings, and other castings subject to vehicle impact or vehicle loading B Special Requirements Provide drainage castings of metal with a Brinell hardness number from 190 to 265. Provide round casting assemblies with lid-to-frame surfaces machine-milled to provide true bearing around the entire circumference. C Foundry Control Before beginning casting, the manufacturer and the Engineer will establish, in conference, a control procedure for correlating casting operations, arranging for foundry inspection, and establishing an approved identification system. Unless the Engineer otherwise agrees, the manufacturer will identify castings as follows:

Calendar Date and tap number, using numerals no greater than 1/2 inch.

1 1/2 inches in the largest dimension or a letter no greater than 3/4 inch high and 2 inches long.

location indicated.

Form these identification marks on castings of sufficient size during manufacture . If the casting size is insufficient for the marks, use stamped metal tags wired to the castings for markings not formed in the castings. Place identification marks, subject to approval by the Engineer, where they will not interfere with assembly of parts and will not be removed during machine finishing operations . Ensure the manufacturer does not place its name on castings except as specified above. D Casting Details Provide castings meeting the dimensions shown on the Plans. Provide draft by increasing the net dimensions. Provide castings within a tolerance of 1/8 inch for the overall general dimensions. Limit the tolerance in dimensions of grates and covers for drainage casting assemblies, and the openings into which they fit, to 1/16 inch. In no case is the metal thickness to be less than 1/16 inch less than the thickness shown on the Plans. Provide castings with a density of at least 95 percent of the theoretical density of that type, based on 442 pounds per cubic foot, cast to the exact dimensions shown on the Plans. Pour castings in closed molds with gating, feeders, risers, and sprues . Ensure castings completely fill the molds. Do not remove castings from the molds until properly cooled. Do not chill the castings. Boldly fillet castings on the inside and reentrant corners. Round the outside corners and edges to a radius of at least 1/8 inch. For Bridge bearings, use a 1/2 inch fillet except where the fillet may interfere with assembly. E Workmanship and Finish Remove attachments of gates, risers, and sprues from the castings and grind remaining extensions flush to the casting surface. The Engineer will reject castings damaged through careless removal of attachments. Do not repair by welding. Fabricate castings free of sponginess, cracks, blow holes, warping, sand inclusions, cold shuts, chilled iron shrinks, and other defects that affect the strength and value of the casting for the purpose intended. Ensure the contact surfaces between different castings in an assembly provide a firm, even bearing, without rattling or rocking. Clean castings of foundry sand, rust, scale, and other deleterious Material .

3321.3SAMPLING AND TESTING

Ensure the manufacturer casts the required number of test bars, as stated below, and machine finishes tension test specimens to the dimensions required in the Schedule for Materials Control . Unless otherwise approved by the Engineer, the manufacturer will deliver test specimens to the Materials Laboratory for testing. Cast three test bars for each heat or tap. If adding alloys in the ladle, cast three test bars for each ladle. For continuous furnace pouring, cast two test bars at the beginning and two test bars at the end of cast. For Bridge bearing castings, cast at least one test bar for each casting. Pour castings and test bars in the presence of the Engineer, unless the test bars are cast as an integral part of the bearing castings. Identify each test bar separately and to the corresponding castings using symbols, letters, or numbers cast on the test bar and casting. If properly identifying castings and corresponding test bars is not possible, the Engineer may require test specimens to be cut from selected castings that are representative of a lot, and perform tests on those samples.