Q : What is the max. temperature surface that I can use the sensors of the MsS unit?

A : In principle, the MsS could be operated up to Curie temperature of the ferromagnetic       material (for example, in Steel, up to 770º C, in Nickel, up to 354º C).       At SwRI, we did test the L-wave mode MsS on a pipe sample whose temperature was       raised up to about 450º C while keeping the MsS ribbon coils and permanent bias       magnets under 80º C.       As expected, the sensor performed well (in fact, the sensitivity was found to increase       with the temperature within the temperature range investigated).       As described in my previous e-mail, the ribbon coils can't be used directly over a high       temperature pipe beyond the maximum of 105º C so that the ribbon coil used for piping       inspection can be used up to 105ºC.       On high temperature piping, we recommend that the MsS be operated over an insulation       layer.       For example, approximately 1-cm-thick insulation will allow the use of the MsS and ribbon       coil on 315ºC pipe.       Although we have not done much R&D for high temperature application, we would do the       following to inspect high temperature piping:       (1) bond nickel strip on the pipe using high temperature adhesive (nickel should good for       up to 300ºC -- Qurie temperature of the nickel is 354ºC over which nickel loses magneto-       strictive properties and wouldn't be useful for guided wave generation and detection).       (2) place an approximately 1-cm-thick insulation layer over the nickel       (3) install Ms sensor over the insulation and operate the sensor in torsional wave mode.       One factor which is not certain presently is the residual magnetization state of the nickel       strip and the actual Ms sensitivity obtainable at that temperature.       If someone wants to know, we will have to conduct actual experimental investigation.