US 4,395,911 A · Method and apparatus for precise determination of girth weld defects

Abstract

Pulses of accoustic energy are transmitted at normal incidence to the wall of a welded pipe, and also at an oblique angle thereto, wherein such transmissions, from respective transducers, occur immediately adjacent a girth weld. Reflected pulses are then received and processed to analyze the radial extent of the girth weld at each interface between the pipe and the weld material. By these means, undercuts or cracks in the weld are detected and analyzed as to their depth and profile. The energy transmitted normal to the pipe wall determines the distance between the pipe and the pulse transducers, and a signal is then generated to simulate a reflection from the inner wall of the pipe with relation to an obliquely-directed pulse. The transducers are then moved axially of the pipe and towards the weld, in small increments, in order to cause the oblique transmission of pulses finally to intercept the weld, thereby producing reflected pulse data when cracks or undercuts are encountered. The heads are also moved circumferentially of the pipe in order to determine the circumferential extent of any undercut or crack.

Claims10

Dependent claims

A method for detecting the depth and profile of an internal undercut or toe crack in a pipe-line girth weld, utilizing pulse reflection techniques, comprising the steps of:

applying ultrasonic pulses of energy to a pipe in said pipe-line, adjacent said weld, at an oblique angle;
generating a signal simulating received pulses which would be reflected from the inner pipe wall as a result of said obliquely applied pulses of energy;
detecting all reflected pulses relating to said obliquely applied pulses;
and
providing an indication of the axial position and radial depth within the weld of each reflected pulse which is received prior to the generation of a corresponding simulation pulse, whereby said indication corresponds to profile information related to the position and depth of an internal undercut or crack.

2 more elements

An apparatus for detecting the depth and profile of an internal undercut or toe crack in a pipe-line girth weld, utilizing pulse reflection techniques, comprising:

means for applying ultrasonic pulses of energy to a pipe in a pipe-line, adjacent said weld, at an oblique angle;
means for generating a signal simulating a received pulse which would be reflected from the inner pipe wall as a result of said obliquely applied pulses of energy;
means for detecting all reflected pulses relating to said obliquely applied pulses;
and
means for providing an indication of the axial position and radial depth within the weld of each reflected pulse which is received prior to the generation of a corresponding simulation pulse, wherein said indication corresponds to profile information related to the position and depth of an internal undercut or crack.

2 more elements

Dependencies are inferred from the claim text.

Method and apparatus for precise determination of girth weld defects

Life of this patent

Method and apparatus for precise determination of girth weld defects

Life of this patent

Abstract

Claims10