Full-scale depressurization of a section of a riser platform. Measurements and comparison with simulations

摘要

Full-scale depressurization tests have been carried out on a riser platform in order to measure outer surface temperatures in the depressurized section of the platform. The tests are performed primarily to find out if the occurring steel temperatures are acceptable during depressurization, and secondly to obtain full-scale experimental data for comparison with the simulation code PIA. Blow-down from two initial pressure levels were tested, 88 and 70 bar. The test section volume was depressurized through a 25 mm nozzle and a pressure of 8 bar was obtained after about 11 and 9 min, respectively. The results of the measurements show that the maximum surface temperature drop is about 9℃ at an initial pressure of 88 bar and 6℃ at an initial pressure of 70 bar. The lowest outer surface temperature registered was -4℃. The depressurization tests were also simulated using the finite difference code PIA, and the results for outer wall temperatures are in close agreement with the measurements. Comparisons between heat transfer coefficients used in the simulation code and estimated heat transfer coefficients from the measurements are also in good agreement.