What is the requirement for surface porosity in welds to be acceptable?

• A. Clusters not exceeding 1/8" in diameter
• B. Clusters should not exceed two in any 4 inches
• C. Surface porosity should not exceed one cluster of 3/32" diameter
• D. Both B and C

Answer: (D)

Surface porosity in welds is an important quality criterion to ensure the integrity and strength of welded structures, such as those used in oil storage tanks. The correct answer highlights the acceptable parameters for clusters of porosity.

Option B specifies that there should not exceed two porosity clusters within a 4-inch span, which helps to limit the occurrence of surface flaws that can compromise the weld's integrity. This is crucial in maintaining structural reliability, as excessive clusters can lead to weaknesses in the overall welded joint.

Option C complements this by stating that the size of any single cluster of porosity should not exceed 3/32" in diameter. This size limit helps to ensure that any potential defects are small enough that they won't contribute significantly to the weakening of the weld.

Together, both requirements from B and C represent a comprehensive standard for evaluating surface porosity in welds, making the combination of these two criteria the appropriate answer.