Is the piping already fabricated? You can spark test welds before or after frp is applied. Need a conductive backing for this. If the frp is not applied, can pressurize with helium and use sniffer to detect leaks. Good luck.
Our company designs,engineers,and fabricates chemical process equipment worldwide including dual laminate piping systems, is such a piping system we have a standard practice of the first exterior over lay to be a layer of carbon fibers followed with 2 layers of 1 1/2 oz. fiberglass matt and this first overlay resin matrix has a conductive added to it such as carbon powder, the type and percentage is important, also the resin matrix must be agitated during fabrication otherwise the percentage of carbon will vary and not achieve the results for conductivity, also its important to note that "back-up" strips are used behind each weld so during spark testing you can get a conductive back-up, you also must be careful in the amount voltage used during the spark test otherwise you may "blow" a hole thru to the thermoplastic pipe.
