Specifications include, but are not limited to: most thorough and complete testing of twelve (12) aerial devices; Cracks No cracks of any type (transverse, toe, longitudinal, crater, etc.) are permitted. Surface Holes The sum of diameters of piping porosity in fillet welds shall not exceed 3/8 in. (10 mm) in any linear inch (25 mm) of weld and shall not exceed 3/4 in. (19 mm) of weld in any 12 in. (305 mm) length of weld. Complete joint penetration groove welds in butt joints transverse to the direction of computed tensile strength shall have no piping porosity. For all other groove welds, piping porosity shall not exceed 3/8 in. (10 mm) in any linear inch (25 mm) of weld and shall not exceed 3/4 in. (19 mm) in any 12 in. (305 mm) length of weld. Lack of Fusion Thorough fusion shall exist between adjacent layers of weld metal and between weld metal and base metal.