Typical glass content testing (LOI) is done in accordance with the ASTM D2584, the test is used to obtain the so-called glass-resin ratio of the pipe wall laminate by measurement of the ignition loss of a cured reinforced sample. Samples, cut from pipe, contained in a crucible are heated in a dedicated oven to 550-650°C and the resin is burned off. The remains of the samples after burning of the resin contain only glass fibers. A comparison of the sample weights before and after the LOI tests allows the determination of the glass resin ratio. At this stage after the LOI test also the fiber architecture of the pipe wall laminate can be studied by peeling off the sample layer by layer.