Fabrication Welding and Maintenance Welding

In most of the production processes welding comprises a major share over other conventional non-conventional processes. Production welding is generally done under optimum conditions because the specifications are set, appropriate equipment is provided for,

chemistry of the base metal is known, the parameters are readily controlled and / or controllable and if necessary, prototypes can be made and subjected to destructive tests to confirm physical properties of welds.

In contrast, maintenance and repair welding present wide disparities compared to production welding. Welding alloys and methods of application must posses special features to overcome handicaps successfully like Fatigue, Unknown Base Metal, In-situ welding, Distortion / Warp age, Limited access etc. 

Special Welding procedure has to be followed critically and trained personnel are required to execute the job.

Repair welding and surfacing are both considered in the field of maintenance welding and are covered together since they are both done by the same welders. Often it is extremely difficult to separate what is considered repair welding from maintenance welding, and surfacing can be included in both situations.

The same basic factors apply to both weld repair and surfacing.
Repaired parts may be more serviceable than the original part, since they can be reinforced and the weaknesses of the original part corrected. It is often more economical to weld repair since the delay in obtaining the replacement part could be excessive and the cost of the new part would normally exceed the cost of repairing the damaged part.