What is the purpose of joint preparation before welding?

The primary purpose of joint preparation before welding is to ensure proper fit-up, clean surfaces, and effective penetration. Proper fit-up is crucial because it aligns the parts to be welded, promoting an even and consistent weld. Clean surfaces are vital as contaminants like oils, rust, or dust can adversely affect the weld quality, leading to defects such as inclusions or porosity. Effective penetration refers to how well the weld metal penetrates the base material; this depth of penetration is essential for achieving a strong bond that can withstand stress and strain once in service.

While enhancing the appearance of the final weld is beneficial, it is not the main purpose of joint preparation. Similarly, testing welding equipment functionality is unrelated to joint preparation, as that involves checking whether the equipment is operational rather than preparing the workpieces. Determining thermal expansion of materials is also separate from joint preparation, as it pertains to understanding how materials behave under heat but does not directly relate to the preparatory steps needed to ensure a successful weld.