Rebar detectors - Can they be used for refractory which is 95% alumina

[QCJT]

Our client doubts if we have achieved a necessary level of insulation inside a header, so we need to measure it's thickness somehow. Thickness measurement of two layers of dried refractory without destroying its integrity seems impossible. So we decided to try to use rebar detectors to measure cover of the stainless steel anchors inside the cast refractory. If that is of proper thickness then same applies to the rest. I'm not sure however if the rebar detectors (such as Profometer's scanlog) are able to work on 95% alumina content refractory.
Besides an opinion about the above I'd appreciate recommendations on how to measure thickness of the refractory in the header.

 

[Ron]

Stainless steels are generally non-magnetic or only slightly so (austenitic stainless steels). So for that reason, they probably won't work. The 95% aluminina refractory could be calibrated for, but you're dealing with a very weak signal at best for the steel.

Check with Olson Instruments in Colorado. They can do some things with one-side thickness measurements in concrete.

 

[QCJT]

Thank you Ron.

I realise that anything working on magnetic fields won't work in our application but I was hoping that something working on Echo is available. We are already in contact with several companies and I'll try Olson Instruments too (or rather their distributors in Europe).

JT

 

[Zambo]

You don't mention the type of refractory or the thickness. From your post it looks as if it is not some kind of brick or block product, is it a castable refractory material? Is there any stainless steel mesh installed in the thickness of the refractory?

Are there any nozzles, manways etc which give you a chance to make some direct measurements?

It is not impossible to repair a refractory lining so destructive testing and then repair should be possible. It will be difficult to drill, measure and patch back but that might be your best option.