Measuring and testing – Vibration – By mechanical waves
Reexamination Certificate
2001-08-14
2003-06-17
Kwok, Helen (Department: 2856)
Measuring and testing
Vibration
By mechanical waves
C073S620000, C073S627000
Reexamination Certificate
active
06578422
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention is directed to: ultrasonic systems and methods for detecting flaws in tubular members; in certain particular aspects, to such systems and methods that are automatic and which accurately detect flaws near or at the ends of a tubular member such as pipe, tubing, casing, or other oil field tubulars; and, in certain aspects, to systems and methods for detecting defects in welds in, on, or between tubular members.
2. Description of Related Art
Flaws and defects in tubular members can result in the failure of the tubulars. Replacement or repair of a defective tubular can be time-consuming and expensive. In the oil and gas industries, tubular members used in drilling and other oil field operations are examined before use to detect and locate defects. Often a defect can be removed and the tubular used for its intended purpose. In other cases, the defect cannot be fixed and the tubular is rejected. Whether the tubular member can be used is based on characteristics of a defect, e.g. size, shape, location and orientation.
In some cases, defects located on a surface (interior or exterior) of a tubular can be visually characterized and examined to determine whether removal of the defect is necessary and possible—and whether removal is feasible by grinding or other means; but often such visual examination of a defect is not accurate or is not possible.
Certain prior art ultrasonic inspection devices have used sonic beams to locate defects in tubular members. In certain systems the apparatus employed uses a piezoelectric crystal or crystals, each of which produces ultrasonic vibrations in response to the application of a voltage. Such systems often use a method in which a crystal is held in a position relative to the pipe surface to transmit a short duration sonic wave pulse of beamed energy into the wall of the pipe at an angle such that a flaw or discontinuity in the pipe causes the waves to be reflected back and produce a voltage response in the crystal, which is then de-energized immediately following the pulsed emission of a sonic wave so that reflected waves can be received during the de-energized periods to produce a corresponding electrical signal which may be analyzed for determining the nature and location of flaws. For example, U.S. Pat. No. 4,217,782 describes an ultrasonic inspection device for inspecting tubular members for the oil and gas drilling industries that employs two pairs of line-focused transducers that transmit sonic beams having a rectangular beam cross-section of about ¾ inch in length. A first pair of the transducers transmits sonic beams longitudinally into the member to detect transverse defects. The second pair transmits sonic beams transversely into the member to detect longitudinal defects. The transducers in each pair transmit sonic beams in opposite directions. Two additional transducers monitor the wall thickness of the tubular member. Sonic beams transmitted longitudinally and transversely are used for the inspection of tubular members since defects are visible to only one or the other. Some flaws and defects are invisible to both longitudinally and transversely transmitted sonic beams. In certain prior art systems, the ultrasonic inspection device of U.S. Pat. No. 4,217,782 has been modified to include four spot-focused transducers that transmit sonic beams having a circular beam cross-section obliquely through a tubular member and a pair of transducers that transmit in opposite directions has been used to detect defects in tubular members as described in U.S. Pat. No. 3,289,468 since a given defect may be invisible to a transducer looking at it from one direction and visible to a transducer looking at it from the opposite direction.
In order to characterize a defect for size, shape, and orientation sonic beams are, in certain prior art systems, transmitted from several different directions followed by the receiving of beams reflected from the defect. As described in U.S. Pat. No. 3,332,278, reflected beams from one transducer have been received by several transducers to detect some of the defects.
U.S. Pat. No. 4,718,277 discloses an ultrasonic inspection device having an array of opposing transducers that longitudinally, transversely, and obliquely transmit sonic beams through tubular members having a range of diameters such that refracted beams meet on the inner surface of the members. Alternate halves of the array of transducers transmit and receive sonic beams reflected from defects in the tubular members using both the pulse-echo and pitch-catch methods.
U.S. Pat. No. 5,007,291 discloses ultrasonic inspection apparatus with centering means for tubular members that has pipe inspection apparatus with transducers for transmitting pulsed beams of ultrasonic energy longitudinally, transversely and obliquely into the wall of the pipe for detection of flaws. The apparatus includes a motor driven chuck for rotating the transducers about the a pipe and a motor driven roller for axial movement of the pipe whereby the transducers move in a helical scanning path. A control system maintains the axes of the pipe and circle array of transducers in coincidence and with hydraulic controls maintains each transducer at fixed distance to the pipe for sonicly coupling thereto by a flowing liquid whereby a shear wave is generated by each beam in the tubular wall. The transducers comprise multiple pairs, the members of which are diametrically opposed and transmit in opposite directions, for transmitting longitudinally at angles of 12 degrees, 27 degrees and 42 degrees to the pipe axis both clockwise and counterclockwise with one transducer of each pair disposed to transmit forward and the other reverse. For longitudinal flaws, one transducer of a pair transmits transverse clockwise and the other transverse counterclockwise. All transducers which transmit in a given direction are arrayed in the axial direction of the pipe. Pulsers simultaneously and repetitively energize and de-energize all forward transmitting transducers and after each such transmission pulsers simultaneously and repetitively energize and de-energize all reverse transducers. Reflection signals of predetermined strength are recorded and activate an alarm. A compressional wave transducer for determining wall thickness is included.
U.S. Pat. No. 5,313,837 discloses an ultrasonic thickness gage for pipe, which in certain aspects is a compact ultrasonic tester involving rotating sensors. A processor rotates with the sensors so that the output signal of the processor goes through slip rings, rather than to output signal of the sensors. A spraying system is incorporated in conjunction with rollers. The rollers take the applied spray on the pipe surface and paint a film on the outer pipe surface to allow a good contact for meaningful results. A floating shoe is provided for holding each sensor against the pipe wall. The sensors are biased into contact with the pipe surface and the machine can handle different diameters of pipe. By controlling the pipe speed of advance and the rotational speed of the sensors, a large percent coverage of the pipe wall is assured. The machine is compact and can be installed behind existing electromagnetic/gamma testers without major modifications to pipe-testing facilities.
U.S. Pat. No. 5,585,565 discloses a method for the ultrasonic inspection of pipe and tubing and a transducer which has an elastic membrane used to form a reservoir of ultrasonic fluid coupled to ultrasonic transducers with the membrane conforming to the surface of the tubing being inspected. Guide wheels maintain the membrane out-of-contact with the tubing during relative rotational movement of the assembly and tubing during inspection. Water is introduced between the membrane and the tubing to provide ultrasonic coupling of the tubing to the transducers through the fluid of the reservoir. Each of the patents mentioned above is incorporated fully herein in its entirety for al purposes.
Known automated ultrasonic systems for detecting f
Kemper Joseph Gregory
Lam Clive Chemo
Kwok Helen
McClung Guy
Miller Rose M.
Varco I/P Inc.
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