GAS-COUPLED, PULSE-ECHO ULTRASONIC CRACK DETECTION AND THICKNESS GAGING

Ultrasonic inspection is a standard method to assess the integrity of large-diameter oil pipelines. Similar methods applied to natural gas pipelines present a considerably greater challenge; gas is a poor coupling agent for the probing ultrasonic signals between the transducer and the pipe wall. Natural gas exhibits a very low specific acoustic impedance compared to oil. Consequently, large ultrasonic-signal transmission losses occur at the transducer/gas and pipe-wall/gas interfaces. To circumvent this obstacle, past exploratory developments included the use of a liquid-filled wheel, electromagnetic-acoustic-transducer (EMAT), and liquid-slug technology. While prototypes of high-speed, in-line inspection systems employing such principles do exist, all exhibit serious operational shortcomings that prevent widespread commercial exploitation.

• Corporate Authors:

  National Institute of Standards and Technology

  Materials Reliability Division
  Boulder, CO  United States  80302
• Authors:
  • Fortunko, C M
  • Schramm, R E
  • Teller, C M
• Publication Date: 1995

Language

• English

Media Info

• Pagination: 8 p.

Subject/Index Terms

• TRT Terms: Cracking; Inspection; Inspection equipment; Natural gas pipelines; Petroleum pipelines; Thickness; Ultrasonic tests
• Subject Areas: Maintenance and Preservation; Pipelines;

Filing Info

• Accession Number: 00728679
• Record Type: Publication
• Files: TRIS
• Created Date: Nov 14 1996 12:00AM