4141.01 DESCRIPTION.
Corrugated steel culvert pipe of circular section, Type I, or pipe arch shapes, Type II, and the coupling bands, special fittings, and associated hardware shall meet requirements of AASHTO M 36/M 36M, unless otherwise specified. The minimum sheet thickness will be shown in the contract documents. When the diameter of round pipe is elongated, one diameter shall be increased by approximately 5%, and each piece shall be permanently marked, at least once inside and once outside to indicate the top.

Types of approved coupling devices are described in Materials I.M. 441. Joint types are standard and positive, and the type may be designated in the contract documents. When not designated, either type may be used.

4141.02 COATED CORRUGATED PIPE.
When coated corrugated pipe is specified, the pipe shall be coated by either of the following methods, at the Contractor's option:

A. Pipe shall meet requirements of Article 4141.01 and AASHTO M 245/M 245M, Type I. The polymeric coating shall have minimum thickness of 0.010 inch (254 µm) on inside surfaces and 0.003 inch (76 µm) on outside surfaces.

B. Aluminized pipe meeting requirements of Article 4141.01 may be furnished.

All breaks or damage to the coating during handling or installation shall be repaired to the satisfaction of the Engineer.