Newer infrastructure has greatly advanced rail vehicles. Today, there are automobiles that can operate on and off railroad tracks. The fastest train in the world, the CRH380A, can reach a top speed of 302 miles per hour. Rail vehicles are a unique travel luxury, since they allow passengers to have the security of being on the ground without any of the hassle that comes with traffic and constant operation. While there generally is an individual guiding these vehicles, the majority of this security is provided by the proper craftsmanship of the materials that let the rail vehicles operate. AWS D15.2:2013: Welding of Rails and Related Rail Components for Use by Rail Vehicles establishes guidelines needed to properly weld these rails so that the vehicles operate properly.
The scope of AWS D15.2:2013 includes not just the welding of railroad rails, but also crane rails, electrical contact rails, girder rails, guard rails and retarder rails. The standard addresses the processes of shielded metal arc welding (SMAW), gas metal arc welding (GMAW), flux cored arc welding (FCAW), flash welding (FW), and thermite welding (TW) that are used to join two rails together. Following construction, the rails should be tested to see if they can support the weight of the vehicles intended for use on them.
Securing the high quality of the rails as they are initially welded is not the only measure that needs to be taken to ensure efficiency and safety. Over time, these rails are due to break down from natural degradation and other factors contributing to damage. The standard advises that rails be inspected visually to determine repairability in accordance with the rail owner’s policy. It is incredibly important to identify the material that comprises a rail to select the correct welding process. For example, a standard carbon metal rail, which has a minimum hardness of 248 BHN (Brinell Hardness Number), would require an arc welding process, either SMAW, GMAW, or FCAW. For any of these to be successful, the rail must be cleaned of any grease or dirt, since this can adversely affect weld quality. An arc weld should be done in a typical chevron pattern. Instructions for this, along with all other welding processes for rails, are described in detail in the standard.
Following any repair on the rail tracks, AWS D15.2:2013 recommends a finish that is smooth and uniform, so that the repairs blend in with the rail to make it appear similar to its original state. All of these rails must have some positive aesthetic qualities, since they can be viewed by people in the vehicles or in the distance.
AWS D15.2:2013 is a standard by the American Welding Society (AWS). It does not address safety for the welders working on the rails. This is covered in ANSI Z49.1:2012: Safety in Welding, Cutting, and Allied Processes.