HT Inflatable Rings

High Temperature (HT) rings and modules are similar to standard EFC inflatable rings but are capable of testing pipes operating at up to 350°C (660°F) provided that the ring is used in the manner specified in GUL's Standard Practice for GWT of High Temperature Pipe-work (GUL 207:2013).

In order to carry out the guided wave inspection, only a 50 cm (20 inch) wide strip of insulation needs to be removed. No couplant is required and the inspection can be performed while the pipe is still on line.

HT inflatable

Accepted Transducer Modules:


HT Module

High Temperature two row adjustable transducer modules with two different spacings to inspect across a wide band of frequency range. These are needed for the ring to reach full operational temperature. Key application areas include:

  • Bare Pipes
  • Painted Pipes
  • Sleeved or Unsleeved Road Crossing Pipes
  • Buried Pipes
  • High Temperature Pipes



The two row adjustable transducer modules used with EFC rings also fit in an HT ring. With four transducer spacings, it is possible to inspect across a wide band of frequency range. The wide frequency range assists in more difficult inspections such as:

  • Buried Pipes
  • Pipes with large numbers of welded supports
  • Inspections for Localised Pitting


Modules w/ HT Modules w/ Adjustable Modules
Number of Channels 16 channels (8 as an option)
Nominal Pipe Sizes 6" to 36" (DN 150 to 900) (join rings to get larger sizes)
Operating Temperature -40° to +350°C (660°F) -40° to +150°C (300°F)
Radial Clearance 63 mm (2.5")
Compatibility Any Wavemaker® instruments


  • HT, HT-HD solid rings are available for smaller diameter pipes.

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