This practice is intended primarily for the mechanized ultrasonic examination of pipe girth welds used in the construction of gas and oil pipelines. This practice, with appropriate modifications due to changes in weld profile, may also be used to examine repaired welds. Manual techniques such as described in Practice E 164 may also be used to examine production or repaired welds. This practice, with appropriate modifications, may also be used to examine other forms of butt welds including long seams.

Techniques used are to be based on zonal discrimination whereby the weld is divided into approximately equal vertical examination sections (zones) each being assessed by a pair of ultrasonic search units. See Fig. 1 for typical zones.

Thicknesses of material examined are normally 7 to 25 mm [0.28 to 1.00 in.] and pipe diameters 15 cm [6.0 in.] and greater but this standard may apply to other thicknesses and diameters if the techniques can be proven to provide the required zonal discrimination.

Examination zones are typically 2 to 3 mm [0.08 to 0.12 in.] in height. For most applications this will require the use of contact focused search units to avoid interfering signals originating from off-axis geometric reflectors and to avoid excessive overlap with adjacent zones.

FIG. 1 Schematic Representation of Weld Zones and Discontinuities