Specifies the procedures to be used for the ultrasonic detection of predominantly longitudinal imperfections in seamless steel tubes, together with reference notches and acceptance criteria. Covers tubes of outside diameters 160 mm and above. Where there is a supplementary requirement stated in the Product Specification for the ultrasonic testing of tube for the detection of predominantly transverse imperfections and/or laminar imperfections, the requirements of Appendix A and/or B shall be applied.