What should the exposed surfaces of each fillet weld specimen demonstrate?

The exposed surfaces of each fillet weld specimen should demonstrate that slag inclusions shall not be more than 1/8" in length or half the pipe wall thickness. This requirement is important because excessive slag inclusions can weaken the weld and negatively impact its integrity. The specified limits help ensure that the weld has adequate strength and performance characteristics, complying with the underlying purpose of API 1104, which is to ensure the quality and safety of welds in pipeline construction.

Understanding the parameters set for maximum acceptable slag inclusion sizes is critical for weld integrity. Keeping inclusions within these limits helps maintain the mechanical properties of the weld, such as tensile strength and ductility, which are vital for the reliable operation of pipelines under various conditions.

The other statements regarding complete penetration and fusion, as well as specific limitations on slag inclusion lengths, are valid considerations in welding quality but are not the specific criteria regarding the exposed surfaces of fillet weld specimens as outlined in this context.