This International 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. This International Standard 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 been performed with necessary consideration of the geometry and acoustic properties of the component, and an adequate sensitivity can be employed to enable the acceptance levels of this International Standard to be applied.