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LONG RANGE ULTRASONICS

The Wavemaker Pipe Screening System is designed for rapid screening of long lengths of pipe to detect external or internal corrosion as well as axial and circumferential cracking. It can be used on a wide variety of pipes including those that are buried or insulated.

A wide range of innovative features has been incorporated into the Wavemaker Pipe Screening System and a user-friendly interface ensures that it is easy to use. The test can be done while the plant is operating so disruption is minimised. Hundreds of metres of pipe can be inspected in a day and 100% of the pipe wall is inspected during a test. The Wavemaker Pipe Screening System is an efficient and effective method of screening.

The Wavemaker Pipe Screening System uses a new two-ring array of probes rather than three as used in earlier applications of this technology. This has proven to be highly effective in terms of its ability to detect the presence of corrosion but with reduced equipment capital cost. The probe arrays can be attached to the pipe in less than one minute.

Two types of guided waves (longitudinal and torsional) are used to broaden the range of possible frequencies and to adjust for different situations, for example the presence of liquids. Axi-symmetric and non-axi-symmetric waves aid in defect detection and interpretation of the results.

All aspects of the system, the electronics, software, probes and the clamping arrangements are designed and manufactured in-house.


Applications

Rapid full coverage screening of pipes by the Wavemaker Pipe Screening System makes it cost effective to inspect pipes in difficult to access locations. There are a number of potential applications of the Wavemaker Pipe Screening System with its ability to detect cracks and general metal loss (greater than 5% of the cross-sectional area). Some of these applications are:

  • The detection and positioning of corrosion under insulation without removing lagging other than for the application of the probes

  • Screening of inaccessible areas such as sleeved road crossings and wall penetrations

  • Screening of on and offshore pipework, even in tightly packed racks.

  • Riser inspection

OFFSHORE

Classification

The following sections classify various test situations into four categories: ideal, good, fair, and specialised. These classifications can be used to separate jobs that will be relatively easy to perform (ideal) from those that require operators with extensive experience (specialised).
 

Test Classification Ideal
General description of application Long straight featureless. Butt welds with the average weld interval being greater than 8 meters. Ease of visual access to pipe. Accurate knowledge of pipe contents. Access can be gained at least 3 meters from a prominent feature.
Examples Long pipe runs commonly found in pipe racks, transmission lines tank farms interconnecting different parts of petro-chemical plants that are in good to fair condition requiring screening to find isolated areas of corrosion.
Typical Performance Test range typically 30 meters plus in either direction from transducer ring.

 

Test Classification Good
General description of application Operating plant pipes. Average butt welds at intervals greater than 5 meters. Limited visual access to pipe. Some knowledge of pipe product state.
Examples Pipes in pipe trenches and service pipes for storage tanks. Inter-connecting pipes between production units.
Typical Performance At least 2.5 meters from closest feature. Tests range generally between 20 and 30 meters in either direction from transducer ring.

 

Test Classification Fair
General description of application Operating plant pipes with the following properties: convoluted geometry with short lengths before features; pipes with a lot of corrosion (i.e. corrosion scale on surface or a high density of deep pits); pipes coated with high density bonded insulation.
Examples Pipework within process units. Any pipe which already visually exhibits severe corrosion. Pipes with factory applied polyurethane foam insulation.
Typical Performance 10 to 20 meters in either direction. Performance reduced as a result of increased attenuation.

 

Test Classification Specialised
General description of application High general corrosion with more than 10% general wall loss caused by pits and general corrosion. Pipes under road crossings. Sleeved or buried pipes. Pipes with internal flaws (erosion and corrosion). Pipes with a high density of Tís and bends, where the average distance between features must be greater than 3 meters. Access can be close to a prominent feature.
Examples Pipes wrapped with bitumen or Denso tape. Pipe sections through concrete, bent header boiler type pipework, heat exchanger tubes and coated riser pipes.
Typical Performance Test range dependent on application but can be between 3 to 15 meters in either direction from transducer ring.