Deals with manual testing of circumferential multipass butt welds between ferritic tubes having an outside diameter of between 25 mm and 120 mm inclusive, though the special measures indicated are necessary for tubes smaller than 37.5 diameter. It is assumed that the weld gaps are underground. Techniques are also suitable in part for stub weld testing. Applicable to the detection and assessment of predominantly circumferential defects in as welded joints. Not applicable to the detection of transverse defects although volumetric defects, such as porosity and slag, may be detected. The requirements apply to testing with probes which are hand held or located in a suitable carrier.