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TRENCHLESS TECHNOLOGY ROADSHOW May 28-29, 2014 – Scotiabank Convention Centre, Niagara Falls, ON
Extending your HDPE pipe investment using Time-of-
Flight Diffraction TestTony Tsang, P.Eng.
Project Manager, Metro Vancouver
Outline• High‐density Polyethylene (HDPE) pipe and its uses• HDPE pipe joint – Butt Fusion and Electro‐fusion• Quality Control / Assurance• Time‐of‐Flight Diffraction (TOFD) Test
• Preparation• Test results• Advantages
• Further work• Questions
• Good flexibility• Strong tensile strength• Good impact resistance• Good abrasive resistance• Good chemical resistance• Light and easy to handle• Leak proof installation
HDPE Pipe
Uses of HDPE pipe• Storm drain• Sanitary sewer• Forcemain• High temperature applications• Directional drilling• Environmental sensitive areas• Poor or sensitive ground
Good performance
demands
Good quality pipe and pipe joints
Quality HDPE pipe joints• Use calibrated fusion equipment• Use certified fusion technician• Adhere to industry best practice• Log data of fusion operation• Test and document test results
• Visual inspection –circumferential inside and out
• Ultrasonic testing –Time of Flight Diffraction (TOFD)
Time‐of‐Flight Diffraction (TOFD) Test•Use 2 probes; one transmitter & one receiver
•Detect the diffracted signals at the edges of abnormality
• The diffracted waves are used to determine the exact location, length and height of the abnormality
Example of TOFD imageHDPE pipe butt fusion joint
Example of TOFD imageHDPE pipe butt fusion joint
Pipe outside surface
Pipe inside surface
TOFD Preparation•Adjust sound frequency, amplitude and sensitivity with respect to the known defects, resin materials and pipe wall thickness and curvature
•Document baseline test results for comparison and evaluation
Usual abnormalities• Lack of fusion
• Incomplete fusion• No fusion
• Void• Hollow space in the joint plane
• pores• Presence of foreign matter such as water droplets, air pockets or other contaminants
Pore
Void or lack of Fusion
TOFD image of flaw
Advantages of TOFD• Test work in any orientation of the abnormality• Flaws can be accurately measured and quantified
Advantages of TOFD• Work in any orientation of the abnormality• Defect height can be accurately measured and quantified• Better probability of detection• Unlike X‐ray, no evacuation is needed• Unlike visual inspection, image is immediately captured as a permanent record
• Remedies can be focused on the specific issues
Advantages of TOFD• Equipment is very light weight• Cost is relatively inexpensive• Contractor can schedule the test to suit their progress• Avoid costly delay• Better quality of the end product• Better performance• Protect the environment• Stretching your investment $
Further work on TOFD• Reduce detection dead zone on the pipe joint surface• Test on electrofusion coupling• Develop and build stronger TOFD expertise • Educate and gain acceptance from
• vendors• service providers• user groups including owners and engineers
• Develop industry best practices, standard and acceptance criteria for the HDPE pipe application in Canada
Questions
Thank you