This work addresses pure collapse experimental tests conducted with DNVGL-450 seamless pipe samples with D/t ratio equal 7.7 and 8.6. Interesting results were achieved, showing that the pipes presented a significant plastic deformation before collapse. There is a limited amount of available technical publications addressing real scale tests with thicker pipes, D/t < 20, that makes the results available quite important for the better understanding of thicker pipes. FEM was conducted and a good correlation with experimental test results were obtained. The experimental and numerical results were correlated with the DNVGL-ST-F101 pure collapse limit state equation, one of the main the rule used in the design of ultra-deep-water subsea pipelines. Conclusions and recommendations for future work based on the results achieved are presented.