Ask the Experts

Q: I’ve heard that RFTC doesn’t work on embedded cylinder pipe that was made without shorting straps or lined cylinder pipe. Is this true?

No, the RFTC system works on both of those pipe types. Here is a summary of the pipe types it works on:

C301 - Prestressed Concrete Cylinder Pipe (PCCP)
- C301E – Embedded Cylinder Pipe (ECP), with or without shorting straps
- C301L – Lined Cylinder Pipe (LCP)
C302 – Non Cylinder Pipe (NCP)
C303 – Bar Wrapped Pipe (BWP)

RFTC will identify wire breaks on both pipe types you mention, but we expect the accuracy of the results to differ due to how the different pipe compositions affect the RFTC signal.

LCP is manufactured with the prestressing wires wrapped directly on the steel cylinder. This solid contact results in clear and consistent signals. Pure Technologies analysts find LCP one of the easiest pipe types to analyze and report the results with high confidence.

On the other hand, ECP without shorting straps is one of the most difficult to analyze. This pipe type is manufactured with the prestressing wires embedded in concrete, resulting in much different electromagnetic signal. The lack of contact to a metal surface can lead to large signal deviations for small numbers of wire breaks. This means identifying the distressed pipes is not the issue, it’s the quantification that is difficult. However, since we expect this to happen, we work around it as there really is no better way than RFTC for identifying which pipes are currently distressed. This involves a further investigation of pipes considered for rehabilitation in order to refine the wire break estimates.

Electrical Continuity Measurements are one common and effective method for refining wire break estimates in ECP without shorting straps. The refined results can then be considered before deciding to repair.

- Allison Biggar, Solutions Manager

Allison Biggar has nearly a decade of experience with PCCP condition assessment. Specializing in the RFTC technology, Allison has worked on projects with some of the largest water utilities in North America. For more information, contact Allison at Allison.Biggar@puretechltd.com.