Pipe-Penetrating Radar (PPR)

Measure Wall Thickness, Rebar Cover, and Voids From Inside the Pipe

What is PPR?

Pipe-penetrating radar (PPR) is SewerVUE's patented application of ground-penetrating radar technology from inside the pipe. Radar antennas traverse the pipe wall and measure reflections from features external to the inner surface. PPR produces quantitative measurements of remaining wall thickness, reinforcement cover, delamination, and external void formation. These parameters are not accessible to conventional CCTV inspection.

PPR surveys are conducted by man-entry crews where confined-space conditions permit, and by remotely operated vehicles in all other cases. The 5th-generation Surveyor and the Asbestos Cement Pipe Scanner are the two ROV platforms designed for PPR deployment.

PPR antennae inside a pipe PPR antennae inside a pipe

SewerVUE's Remotely Operated Vehicles

How Does it Work?

PPR is a pipeline inspection technology that uses GPR to investigate the subsurface of the Earth by emitting electromagnetic (EM) waves and measuring the reflected signals. PPR is the adaption of this technology for use from inside pipes.

Example of PPR data

Example PPR data with interpretation overlaid. Green traces the pipe wall; the red line identifies rebar; red patches indicate voids external to the pipe.

EM waves have two important properties: they travel at different speeds through different materials, and the amplitude of their reflections is greater depending on the contrast between two materials. By measuring the two-way travel time and the amplitude of the reflected EM waves, a detailed image of the subsurface can be built. By repeating this process continuously along a survey line, a profile of the line is created. This can be done at multiple clock positions to provide a detailed report on the pipe’s current condition, as well as the presence or absence of voids outside the pipe wall.

The most commonly deployed ROV, the Surveyor, carries two PPR antennae. These can be adjusted to collect data from any two clock positions between 9 and 3 o’clock. In a typical survey, lines of data are collected from two clock positions as the robot moves in one direction, and two different positions as the robot returns to the deployment point. This results in four lines of PPR data with just one deployment. The PPR antennae on the Surveyor transmit at 1.6 GHz or 2.3 GHz frequencies, which results in signal penetration depth of up to 920 mm.

Combined with LiDAR and CCTV information collected simultaneously, PPR surveys can provide actionable information with a safe, cost-effective method. Contact us to find out how PPR can meet your needs.