Non-destructive testing of pipes

• US 7,475,596 B2
• Filed: 12/07/2007
• Issued: 01/13/2009
• Est. Priority Date: 06/21/2005
• Status: Active Grant

• Current Assignee: Mueller International LLC (Mueller Water Products Incorporated)
• Original Assignee: National Research Council Canada
• Inventors: Bracken, Marc, Wang, Alex, Hunaidi, Osama
• Primary Examiner(s): Williams; Hezron E.
• Assistant Examiner(s): SAINT SURIN, JACQUES M
• Application Number:
  US11/952,582
• Publication Number:
  US 20080078247A1
• Time in Patent Office: 403 Days
• Field of Search: 735/92, 735/97, 735/98, 736/02, 736/22, 738/614.2
• US Class Current: 73/592
• CPC Class Codes: G01B 17/02 for measuring thickness
• CPC Class Codes: G01M 3/243 for pipes
• CPC Class Codes: G01N 2291/011 Velocity or travel time
• CPC Class Codes: G01N 2291/02827 Elastic parameters, strength or force
• CPC Class Codes: G01N 2291/02854 Length, thickness
• CPC Class Codes: G01N 2291/2634 cylindrical from outside
• CPC Class Codes: G01N 29/07 by measuring propagation velocity or propagation time of acoustic waves
• CPC Class Codes: G01N 29/222 Constructional or flow details for analysing fluids optoacoustic fluid cells G01N29/2425
• CPC Class Codes: G01N 29/4418 with a model, e.g. best-fit, regression analysis

Abstract

To perform a non-destructive condition assessment of a pipe carrying a fluid, an actual value representative of the propagation velocity of an acoustic disturbance propagating between two longitudinally separated points on the pipe is determined. A corresponding predicted value for the propagation velocity is computed as a function of at least one wall thickness parameter of the pipe by using a theoretical model for the propagation of acoustic waves in the pipe that assumes said pipe has a finite wall thickness with a predetermined circumferential thickness profile. The wall thickness parameter is then computed by matching the actual value with the predicted value, for example, by substituting the actual value in a formula predicting the theoretical value.

Claims

1. An apparatus for the non-destructive condition assessment of a pipe carrying a fluid, comprising:

a) first and second sensors for detecting an acoustic disturbance propagating past two longitudinally separated points on said pipe; and

b) a processor receiving inputs from said first and second sensors and programmed to;

(i) determine an actual value representative of the propagation velocity of said acoustic disturbance;

(ii) compute a corresponding predicted value for the propagation velocity as a function of at least one wall thickness parameter of said pipe by using a theoretical model for the propagation of acoustic waves in said pipe that assumes said pipe has a finite wall thickness with a predetermined circumferential thickness profile; and

(iii) compute said wall thickness parameter by matching said actual value with said predicted value.

2. An apparatus as claimed in claim 1, wherein said pipe is a water pipe, and said sensors are mounted on support elements selected from the group consisting of:

hydrants connected to said pipe, control valves attached to the pipe, and the pipe wall accessed via manholes or small excavated keyholes in the soil.

3. An apparatus as claimed in claim 1, wherein said sensors are inserted into the pipe individually or as arrays thru fire hydrants or corporation stops.

4. An apparatus as claimed in claim 1, wherein said model includes the velocity of propagation of the disturbance in the unbounded fluid or the bulk modulus elasticity of the fluid, the fluid'"'"'s density, the pipes'"'"'s internal diameter and wall thickness, and Young'"'"'s modulus of the material forming the pipe.

5. An apparatus as claimed in claim 1, wherein said sensors are connected to wireless transmitters, and said processor is connected to a receiver for remotely picking up signals from said sensors;

or said sensors are connected to said processor via cable.

6. An apparatus as claimed in claim 5, further comprising a reference pipe of known wall thickness profile to permit at least one constant in said theoretical model to be back calculated from actual velocity measurements.

7. An apparatus as claimed in claim 1, wherein said processor is included in a PC or a specially designed device.

8. A storage medium storing coded instructions for instructing a computer to:

accept signals from sensors responsive to an acoustic disturbance propagating along a pipe;

compute an actual value representative of the propagation velocity of said acoustic disturbance by dividing the difference between the distances of said sensors from corresponding acoustic source by the time delay between said acoustic disturbances;

compute a corresponding predicted value for the propagation velocity as a function of at least one wall thickness parameter of said pipe by using a theoretical model for the propagation of acoustic waves in said pipe that assumes said pipe has a finite wall thickness with a predetermined circumferential thickness profile; and

compute said wall thickness parameter by matching said actual value with said predicted value.

9. A storage medium as claimed in claim 8, further including instructions for instructing said computer to calculate constants for use in said theoretical model from measurements performed on a reference pipe of known wall thickness.

10. A storage medium as claimed in claim 8, further including instructions to cause said computer to display an input screen for accepting inputs relating to known pipe parameters for use in the computation.

11. A storage medium as claimed in claim 10, wherein said constants include the velocity of propagation of the disturbance in the unbounded fluid and the bulk modulus of the material forming the pipe.