This standard specifies ultrasonic acceptance levels 2 and 3 for full penetration welded joints in ferritic steels, which correspond to ISO 5817 quality levels B and C. An acceptance level corresponding to ISO 5817 quality level D is not included in this standard as ultrasonic testing is generally not requested for this weld quality.These acceptance levels are applicable to testing carried out in accordance with ISO 17640.ISO 11666:2010 applies to the examination of full penetration ferritic steel welds, with thicknesses from 8 mm to 100 mm. It can also be used for other types of welds, materials and thicknesses above 100 mm, provided the examinations have