Pipe flaw detector

Details Pipe flaw detector Pipe flaw detector

2002-11-06

2004-08-10

Williams, Hezron (Department: 2856)

Measuring and testing

Vibration

By mechanical waves

C073S638000, C073S639000

Reexamination Certificate

active

06772636

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to pipe flaw detectors and, in one particular aspect, to a manually operable defect locator.
2. Description of Related Art
The prior art discloses a variety of systems for inspecting pipe and tubulars which are used to detect and locate both inner diameter and outer diameter flaws and defects. These systems provide a fairly accurate flaw location on the pipe and, in the case of an “oblique” flaw, a measurement of an angle of the flaw with respect to the longitudinal axis of the pipe or tubular. Following this detection and location of the flaw, personnel visually locate the flaw so that an attempt may be made to grind the flaw away or grind it to such an extent that the pipe wall thickness at that location is within certain acceptable limits.
In the past systems and apparatuses for the post-inspection location of a flaw have included a hand-held ultrasonic probe. Certain of these prior art apparatuses and systems provide inaccurate flaw locations and do not adequately deal with differences in tubulars' outer curvature.
There has long been a need, recognized by the present inventors, for an easily manipulable device or apparatus for post-machine-inspection flaw location. There has long been a need for such a device or apparatus which provides an accurate location of a flaw.
SUMMARY OF THE PRESENT INVENTION
The present invention, in certain embodiments, discloses a post-machine-inspection pipe flaw detector that provides an operator a precise determination of flaw location. In one aspect, such a detector is a hand-held manually manipulable device with a search head with one or more ultrasonic probes that is movable over a pipe or other tubular. By setting an adjustable direction device, such a detector can be used to detect transverse, longitudinal and oblique flaws. The ultrasonic probe (or probes) is connected to a typical ultrasonic probe system with instrumentation, receiver(s), processor(s), display(s), etc., as are well known in the art and are commercially available. A coupling device, preferably with a flexible member for conforming to a tubular's curvature, (e.g., but not limited to, a water-filled bladder and a flexible ultrasonic wave guide) is positioned beneath the ultrasonic probe(s) for contacting the pipe with the flaw (or flaws) to be located. An operator, who has information generated by a previous machine inspection of the pipe and knows the general flaw location and orientation, places the detector in the known area of the flaw moving the detector around, if necessary, to precisely locate the flaw.
The search head of the detector has a movable dial member with angular marking indicators from 0° to 180° which correspond to possible angular measurements of the angle of a flaw's orientation (previously determined by the machine inspection) with respect to the longitudinal axis of the pipe. The operator sets the dial member's angular indicator to the previously-measured angle of the flaw determined by the previous inspection, and this moves the ultrasonic probe position on the dial member so that its angular orientation with respect to the pipe's longitudinal axis corresponds to the angular setting of the dial member and thus to the angle of the flaw with respect to the pipe's longitudinal axis.
This facilitates the location of the flaw and indicates that a detected flaw is the flaw indicated by the previous machine inspection.
Once the operator has located the flaw it is possible to grind, sand, or otherwise abrade the flaw in an effort to bring the pipe wall thickness at the flaw location into acceptable tolerances, e.g. in one particular aspect, within 5%, plus or minus, of the average acceptable wall thickness. Such grinding can reduce stress at the location of a flaw.
In certain embodiments one or more rollers are provided at the lower surface of the search head to facilitate the movement of the search head over a pipe's outer surface. In certain aspects a handle is connected to the head for holding the head and, optionally, such a handle may have one or more rollers on its lower surface for contacting the pipe's outer surface. Alternatively, the search head may have an upper handle with or without roller(s) to facilitate its movement and handling by an operator.
In one aspect connections are provided on the search head for introducing and evacuating a coupling fluid, e.g. water, to the bladder positioned beneath the ultrasonic probe(s) and/or for evacuating air from the bladder. These connections may extend through the dial member or through any other suitable part of the search head or handle (if one is present).
optionally, one or more additional ultrasonic wall thickness probes may be mounted on the search head [e.g., on the dial, body or handle]. In certain aspects, apparatus according to the present invention is used for primary flaw detection—i.e., a previous inspection by machine is not done.
It is, therefore, an object of at least certain preferred embodiments of the present invention to provide:
New, useful, unique, efficient, non-obvious devices for post-machine-inspection location of pipe or tubular flaws and defects;
Such devices which accurately locate longitudinal, transverse, and oblique flaws;
Such devices which are easily manipulable and easily handled by an operator;
Such devices which in one aspect have one or more rollers to facilitate movement over a pipe or tubular's surface and, in certain aspects, facilitate proper alignment of the device with respect to a tubular and/or with respect to a flaw; and which, in one particular aspect, have at least two spaced-apart pairs of rollers to span portions of a tubular's curved surface to correctly position a device according to the present invention with respect to a longitudinal axis of the tubular;
Such devices with one or more roller apparatuses to maintain a desired distance between an ultrasonic transducer and a tubular surface and/or flaw;
Such devices which can detect and distinguish between inner diameter and outer diameter flaws;
Such devices with angular indicators to correctly align an ultrasonic probe on the device with a flaw that is at an angle to the pipe axis to facilitate detection of such a flaw;
The present invention recognizes and addresses the previously-mentioned problems and long-felt needs and provides a solution to those problems and a satisfactory meeting of those needs in its various possible embodiments and equivalents thereof. To one of skill in this art who has the benefits of this invention's realizations, teachings, disclosures, and suggestions, other purposes and advantages will be appreciated from the following description of preferred embodiments, given for the purpose of disclosure, when taken in conjunction with the accompanying drawings. The detail in these descriptions is not intended to thwart this patent's object to claim this invention no matter how others may later disguise it by variations in form or additions of further improvements.


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Ultrasonic NDT Instruments and Systems, Matec Instruments Companies, 2001.
Truweld Ultrasonic Weld Line Inspection System, Tuboscope, Inc., 2001.

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