Section 4187. Materials for Support Structures.

A. Material for Aluminum Alloy Superstructure.

1. Extruded Tubes.
ASTM B 221/B 221M, Alloy 6061-T6, shall apply.

2. Aluminum Plate.
ASTM B 209 B/209M, Alloy 6061-T6, shall apply.

3. Aluminum Casting Components.
ASTM B 26/B 26M, Alloy 356.0-T7, shall apply for components in which welding is involved.

Aluminum castings for handrail pipe fittings shall meet requirements of ASTM B 26/B 26M, Alloy B 514.0 Temper F. All other aluminum castings shall meet requirements of ASTM B 26/B 26M, Alloy 356.0-T7, or Alloy B 443.0 Temper F.

4. Aluminum Structural Shapes.
ASTM B 308/B 308M, Alloy 6061-T6, shall apply.

5. Aluminum Catwalk Gratings.

a. Longitudinal (Bearing) Elements.
ASTM B 221/F 221M, Alloy 6061-T6, shall apply.

b. Transverse (Cross) Elements.
ASTM B 221/B 221M, Alloy 6063-T5, shall apply.

Other aluminum alloys will be considered for approval in alternate designs of catwalks which may be submitted for approval.

6. Aluminum Pipe.
ASTM B 241/B 241M, Alloy 6063-T5, shall apply.

7. Aluminum Weld Wire for Welding Electrodes.
AWS A5.10 electrode ER5356 or ER5556 shall be used when welding aluminum alloy 6061.

B. Materials for Galvanized Steel Superstructures.
Materials for galvanized steel superstructures shall be of the type and quality specified in the contract documents.

C. Fasteners for Aluminum Alloy and Galvanized Steel Superstructures and Anchor Bolts.

1. Material for Superstructure.

a. Stainless Steel Bolts and Studs.
Stainless Steel Bolts and Studs shall be of the size designated in the contract documents, shall meet requirements of ASTM A 320/A 320M Type 304 or ASTM F 593 Group 1, 2, or 3 Condition A.

Bolt heads shall be hexagonal and shall conform to ASTM A 320/A 320M. Threads shall conform to ANSI B1.1 for UNC thread series, Class 2A fit. The stress area shall be used to compute the tensile strength.

b. Stainless Steel Nuts.
Stainless Steel Nuts shall be of the size designated in the contract documents, shall meet requirements of ASTM F 594, shall be of alloy group 1, 2, or 3, and shall meet a minimum proof load of 75,000 psi (517 MPa).

Nuts and jam nuts shall be hexagonal and shall conform to requirements of ASTM F 594. Threads shall conform to UNC thread series, Class 2B fit. In lieu of jam nuts, stainless steel lockwashers may be used.

c. Stainless Steel Washers.
Stainless Steel Washers shall conform to ANSI B18.22.1 for the bolts specified. Washers with dimensions other than those specified may be approved by the Engineer.

d. Stainless Steel U-Bolts.
Stainless Steel U-Bolts shall meet requirements of ASTM A 320/A 320M, Type 304 or ASTM F 593 Group 1, 2, or 3 Condition A and shall be the size specified in the contract documents.

2. Anchor Bolts, Nuts, and Washers.
Welding of anchor bolts will not be allowed. The anchor bolts shall meet the requirements of ASTM F 1554, Grade 105 (724 MPa), and be full-length galvanized. Anchor bolts shall be the Unified Coarse Thread Series and have Class 2A tolerance. The end of each anchor bolt intended to project from the concrete shall be color coded in red to identify the grade. Washers shall be galvanized and shall meet the requirements of ASTM F 436. Nuts shall meet the requirements of ASTM A 563, DH, be heavy hex, and be galvanized. Nuts may be over-tapped in accordance with the allowance requirements of ASTM A 563. Galvanizing shall meet the requirements of ASTM A 153, Class C; or ASTM B 695, Class 50.

D. Material for Substructure.

1. Concrete Footings.
Class C concrete meeting applicable requirements of Section 2403 shall be used in footings.

2. Reinforcing Steel.
Section 4151 shall apply.

E. Conduit.

1. Substructure.
Conduit placed in the substructure shall be one of the following:

Rigid steel or rigid plastic conduit meeting the requirements respectively of Article 4185.10, A or C, or bituminized fiber conduit meeting requirements of FZS W-C-581, Type II.

2. Superstructure.
Conduit placed in the superstructure shall be rigid steel specified above when the structure is fabricated from steel, and shall be aluminum alloy when the structure is fabricated from aluminum alloy.