To demonstrate the leak sealing pressure containment capacity of a composite repair system, ISO 24817 requires that 9 short term pressure tests are performed on pipe spools containing a through wall defect. From this test data, ISO 24817 defines the statistical analysis to determine the lower confidence limit of the energy release rate, γLCL. This energy release rate (which is effectively a measure of the adhesion strength of the repair system) is a function of the pipework material, the surface preparation procedure and the composite repair system.

The following case study summarises the pressure testing and analysis performed to determine the γLCL for the Futurewrap Glass/LT repair system on carbon steel pipework where the surface preparation is to Sa2.5.
The 9 short term pressure tests were performed on 6 inch pipe spools, material API 5L grade B. These test spools had a 10 mm diameter through wall defect drilled through the pipe wall. The pipe spools were grit blasted to Sa2.5, see Figure 1.

Artificial defects (2 mm thin plastic sheet) of diameter 15, 25 and 35 mm respectively were placed over the through wall defect, see Figure 2.