**1. Introduction**

Welded connections play a substantial role in the manufacturing processes of many types of parts, structures, equipment, and materials. Equipment manufacturers for vehicles and implements use a considerable amount of advanced welding techniques and applications throughout the design of their manufactured products. In the industrialized world, frequent breakdowns, failures, and the necessity of repairs are a part of ongoing operations. Mechanical and structural component failures are inevitable, particularly with mobile agricultural and construction equipment. Therefore, it is essential for engineers, field technicians, and those in similar roles to be educated on the characteristics of a successful weld repair, welding fundamentals, and the associated challenges of executing field repairs.

Identifying the engineering challenges of field repairs will be examined first. Properly executed welding techniques incorporate an extensive amount of engineering fundamentals to maintain the original assembly's design and ensure adequate structural integrity once complete. There are many types of welding repairs that can

be categorized by location, component type, design criteria, and the degree of critical quality requirements. Understanding basic material properties and identifying the material to be repaired is important for the welding process selection and the structural analysis of the proposed repair design. Certain repairs may not be accessible enough to clean the mill-scale, corrosion, or debris away, thereby narrowing the choice of possible welding processes, so repair preparation may also influence the welding process selection.

Understanding the various types of welding processes is vital to a manager seeking repairs. Each welding process features unique characteristics, often making one process more suited for a specific repair than other potential processes, based on the technical characteristics of the welding process equipment. Identifying the base material properties and measuring the thickness of pieces are both easily quantifiable metrics that are used to determine the proper weld size. For economic reasons, this analysis is always performed in manufacturing applications, but it is also necessary for quantifying the strength of a repair weldment to ensure that enough weld material has been applied to a given joint. Weldment strength mathematical field calculations will be examined in the chapter and illustrated with appropriate figures.

Finally, challenges for field engineers and technical managers will be summarized with emphasis on the identification of weld defects, preventative methods, and suggestions that can be used to minimize the occurrence of weld defects when conducting field repairs. Technical procedures for weld quality examination in field repairs should be useful for managers when instructing repairmen on alleviating defects or challenges within a job. Finally, the chapter concludes with a discussion of the importance of repairs to business enterprises. There is value in having basic welding technical knowledge for an array of industry specialists. This chapter seeks to promote further education and interest in the engineering properties of welding repairs, their application to practical problems, and provide some value to operational managers utilizing heavy field equipment.

A variety of primary sources have been used for this chapter. Various sections of Blodgett's *Design of Welded Structures* (1972) are used heavily throughout the chapter [1]. This classic textbook incorporates a significant amount of published welding calculations, and its primary focus is on welding in industrial and manufacturing environments. However, many of the calculations and formulas are valid across all fields of welding technology and application. Information regarding material properties and analysis comes from the *American Society of Mechanical Engineers* (ASME), the *American Institute of Steel Construction* (AISC), and the *American Society for Testing Materials* (ASTM) publications. These organizations are responsible for writing many of the technical standards and recommended protocols for design, material testing, and property specification in the industry. Codes and practical definitions regarding welding standards are from the *American Welding Society's* (AWS) *Structural Welding Code* [2]. The AWS provides detailed information in its standards for a diverse array of welding applications. Various standards include code requirements, measurements, strength, specific practice recommendations, given constants for equations, education, safety practices, and other facets of welding. Where appropriate, the reader will be directed to primary sources for specific information.
