Guided Wave Ultrasonic Testing

TWI has been the pioneer of long-range guided wave technology, also known as long-range ultrasonic testing (LRUT), since the mid-1990s. This research was stimulated by the need of the oil and petrochemical industries for a method to detect corrosion under insulation (CUI) in pipework and subsequently led to the development of the first commercial guided wave system, Teletest, which is

commercially available through TWI's subsidiary company, Plant Integrity. The technique is now widely accepted and used to inspect pipes in inaccessible areas such as road and river crossings, power plant tubing, risers, offshore topside pipework, jetty lines and refinery pipework.

TWI and Plant Integrity in partnership have further developed the technology, and Plant Integrity is currently selling its fourth generation equipment for inspection of pipelines: Teletest Focus+.

The basic system consists of:

A low-frequency flaw detector, the Teletest Focus+ pulser receiver unit

Transducer ring or tool that wraps around the pipe

A laptop computer that contains the software controlling the system

Cable connector between the Teletest Focus+ unit and tool

Communication between the Teletest Focus+ unit and laptop through ethernet

TWI Resources

The combined TWI and Plant Integrity resource in the field of LRUT comprises some 30 highly skilled engineers and technicians. This makes it one of the largest groups in the world working in the field of guided waves. TWI's activities concern the development of new applications for LRUT technology,

while Plant Integrity concentrates on enhancements to the Teletest range of equipment for sale to

NDT service providers and inspection companies and on the provision of LRUT services worldwide.

Applications Proven applications

Teletest has been used commercially over ten years. During this time its benefits have been proven on:

Painted pipework Road crossings

Mineral wool insulated lines Offshore risers

Polyurethane foam insulated lines Sleeved sections

Bund wall penetrations Spirally welded pipe

Buried pipelines Sleeved sections

High temperature lines (

Teletest Product Range For further information on the Teletest product range :

Teletest Focus

Flaw Detector

Inflatable Collars

Multi-Mode modules

Mini-tools

Teletest WaveScan Software

Teletest Focus Plus Teletest was the first commercially available system to utilise long-range guided wave ultrasonic testing for

detecting corrosion in pipelines. TWI developed the technology in response to requests from industrial

members in the oil, gas and petrochemical industries. These companies required an non-destructive testing

(NDT) method capable of detecting corrosion in pipes and pipelines at areas inaccessible for inspection by

conventional NDT methods, ie. insulated and sleeved pipework, or pipelines running under roads or elevated

on pipe racks. The original Teletest equipment has been replaced by a system with greatly enhanced

capability and the flaw detector is sold under the Teletest Focus + trademark.

The basic system consists of:

A low frequency flaw detector, the Teletest Focus unit

Transducer ring or tool that wraps around the pipe

A lap-top computer that contains the software for controlling the system

Cable connector between Teletest Focus unit and tool

Umbilical between Teletest Focus unit and laptop

For further information on guided wave activity please find below a link to a 40 minute presentation on the TWI

Flaw Detector Plant Integrity Ltd has announced the launch of the Teletest Focus+ Guided Wave Pulser-receiver unit. This system

will replace the successful Teletest Focus unit which was introduced to the market four years ago.

The development of the Teletest Focus+ unit has taken 2 years of collaboration between Plant Integrity, key

industrial partners and TWI's Long Range Ultrasonics Group in order to provide a pulser-receiver unit that not

only improves Guided Wave inspection for site technicians but also provides the optimum platform for Guided

Wave Research and development for TWI and other University Institutes.

The key improvements to the pulser-receiver unit are Ethernet communications and 24 fully independent transmit

and receive channels to speed up data collection. Better range and sensitivity has been achieved due to

maintaining the Teletest standard output voltage of 300V Peak to Peak with improved sampling resolution and

filtering.

Weight has not been compromised for this added functionality with a 45% reduction to 7.6kg over the previous

unit.

Key features introduced in the previous pulser-receiver unit such as the internal electric pump for inflation of

collars and GPS have proved so popular that they have been kept within the new unit also. Inspection of pipelines

is still operated in octants to fully utilise the A-Map (unrolled pipe) and secondary focussing technique unique to

Teletest.

The Teletest Focus+ system is fully back compatible with tooling and Teletest WaveScan software. Teletest

operates in Multimode configuration as standard uniquely providing both longitudinal and torsional wavemode

inspection simultaneously. In addition, a new five ring Torsional module has been launched that provides a high

amplitude, broad frequency range torsional inspection when that additional power is required, without the need

to change transducer spacing.

Inflatable Collars The one-piece collar, made out of state of the art carbon fibre reinforced Kevlar, are thinner and 60% of the

weight of the current standard. The new design has reduced the necessary clearance between pipes to 65mm.

This is often an important consideration, where many pipes run in close proximity. The collar is clamped around

the pipe with a rapid latch mechanism and can be mounted in under a minute

Multi-Mode Modules The multi-mode modules accommodate five transducer elements, three to excite the longitudinal mode and

two to generate torsional waves. Each mode has its pros and cons for flaw detection in a given situation. Multi-

mode capability ensures that the wave mode is optimised for the specific pipe being inspected.

Mini Tools Plant Integrity has developed 'LATCH and FIRE' mini-tools to inspect 1.5 -5" diameter pipes. These represent a

step change in efficiency compared with cumbersome 'fixed ring' tools. They have brought about a 90%

improvement in set up time and only require 42mm clearance between pipes.

Teletest Wavescan Software

The release of Teletest WaveScan software incorporating focussing has been timed to coincide with the launch

of the Teletest Focus hardware. The WaveScan software runs on Windows 7 and streamlines collection and

interpretation of data with many features automated for speed and ease of use. Full data collection and

interpretation at a given test location can be completed in 15 minutes.

The software incorporates an automated frequency sweep facility enabling data to be collected at a range of

frequencies, so that frequency can be optimised for the test pipe. In addition the WaveScan software

incorporates the focussing and A-Map functions which gives circumferential distribution of defects around the

pipe. It also sets the Distance Amplitude Correction (DAC) curves automatically from the peaks of weld

indications.

Another feature that greatly improves interpretation is the ability, with one mouse click, to switch between

displays. The software also has an automated reporting facility, integrated with Microsoft Word, for improved

productivity.