Vol.10, No3, 2010, pp.187-192
UDC  621.51-192

Fitness for service analysis can be an answer to questions about possible safe operation when a flaw is detected either during service or scheduled shutdown. In some cases repair may not be an option due to the lack of resources, access within the original shutdown window, lack of repair part, or the risk of further damage during the repair itself. However, the methodologies and numerical tools are developed, engineers have to face difficulties during the analysis of old parts due to the lack of reliable information about the material, load history or environmental effects. In the present case a crack is found in a giant, more than 20 years old, gas compressor, between one of the inlet valve seats and the cooling pipe row. A failure analysis of a cracked cylinder of the compressor was made using complex numerical and experimental methods. The operating parameters and probable lifetime (due to crack propagation) on reduced pressure are given based on the results of the investigations.

Keywords: ammonia compressor, crack, finite element method, temporary repair, integrity and life assessment