When welding ASTM A913 steel thicker than 1 1/2 inches without preheat, what is the maximum allowable diffusible hydrogen from the filler metal?

The maximum allowable diffusible hydrogen from the filler metal when welding ASTM A913 steel thicker than 1 1/2 inches without preheat is correctly set at 8 ml/100g. This specification is crucial because high levels of diffusible hydrogen can lead to hydrogen-induced cracking, particularly in thicker steel sections where heat dissipation is slower and the risk of such defects increases.

In welding, controlling diffusible hydrogen content is essential to ensure the integrity and performance of the weld joint. By adhering to the specified limit of 8 ml/100g, welders can help mitigate the risk of cracking in the weld and heat-affected zone, maintaining the overall quality of the weldment in these thicker materials. This is particularly relevant for ASTM A913, which is a specification that applies to high-strength steel structures.

The other options indicate lower or higher amounts of diffusible hydrogen that do not align with the established guidelines for this specific application and material, potentially compromising the weld integrity.