Three dimensional mapping of corrosion pits in cast iron pipe using the remote field effect
: The remote field effect is an electromagnetic method for inspecting pipes and tubing. It has recently been commercialised as a technique for inspecting gray cast iron and ductile iron water mains. How-ever, commercial tools provide information on pits depths in the pipe and overall wall loss. Models of the mechanical behaviour of cast iron pipe also require information on pit width and length. This paper discusses remote field effect apparatus and experimental techniques used in the laboratory to produce three dimensional electromagnetic field maps. The maps shown in the paper indicate that sizing corrosion pits in three dimensions is possible using the remote field effect. Further research needs are also discussed.
The phantom exciter: high resolution measurements of RFEC slit defect interactions
In order to obtain a better understanding of defect interactions associated with the Remote Field Eddy Current technique, a new exciter/detector geometry has been used. The Phantom Exciter geometry uses a single through-wall transmission and allows high resolution measurements to be made in the region of a defect. Strong response to axial slits in nonferrous pipes due to eddy current interaction has been demonstrated. Magnetic interactions in ferrous pipe has lead to good responses to circumferential slits
On the estimation of frost loads
Frost load is an important loading condition to consider for the design of buried pipes. Though frost loads can be much greater than earth loads, it is not presently possible to estimate frost loads except using heuristic arguments. This paper describes the development of simplified methods to estimate frost load. Important variables are identified that can explain how the effects of frost loading can be mitigated. Sensitivity analyses are presented to highlight the importance of the different variables involved in the simplified methods. Frost loads measured in a field case study are compared with calculated frost loads in trenches with clay and sand backfills. Key words: frost load, frost depth, buried pipe, trench backfills, trench width.