This specification covers the minimum welding requirements applicable to welded structures used in the railroad industry. It is not intended to apply to tank cars, their associated piping or to the welding of rails. Recommended practices for welding railroad rails and related components are being developed as a separate AWS document. Part I gives the general requirements for welded construction for metal components 1/8 in. (3.2 mm), or greater, in thickness. Part II provides specific requirements for the welding of freight cars. Part III covers specific requirements for the welding of locomotives and passenger train vehicles with emphasis on the welding of base metals less than 1/8 in. (3.2mm) in thickness.

References to the manufacturer apply to the original builder as well as any organization performing repairs or alterations to such equipment. 

Requirements contained herein constitute acceptable industrial practices. They are not intended as a substitute for engineering judgment with respect to the suitability of application of listed joints to a welded structure. Manufacturers shall be responsible for the quality of the welding performed by their organization and shall perform whatever tests are necessary beyond the requirements of this specification to assure that the welds are satisfactory for the intended application. 

Requirements contained herein are not intended to nullify or void the requirements of any law or govern- a mental agency regulation nor any specification of the Association of American Railroads. 

All references to the need for approval shall be interpreted to mean approval by the Engineer. The Engineer is the agency or representative of the AAR delegated to enforce the specifications or construction regulations and the individual designated by the owner, purchaser, or operating railroad, as applicable, acting on the owner's behalf on all matters within the scope of this specification.