The effect of pressure and temperature on microbial communities of marine environments contaminated with petroleum hydrocarbons is understudied. This study aims to reveal the responses of marine bacterial communities to low temperature, high pressure, and contamination with petroleum hydrocarbons using seawater samples collected near an offshore Brazilian platform. Microcosms containing only seawater and those containing seawater contaminated with 1% crude oil were subjected to three different treatments of temperature and pressure as follows: (1) 22°C/0.1 MPa; (2) 4°C/0.1 MPa; and (3) 4°C/22 MPa. The effect of depressurization followed by repressurization on bacterial communities was also evaluated (4°C/22 MPaD). The structure and composition of the bacterial communities in the different microcosms were analyzed by PCR‐DGGE and DNA sequencing, respectively. Contamination with oil influenced the structure of the bacterial communities in microcosms incubated either at 4°C or 22°C and at low pressure. Incubation at low temperature and high pressure greatly influenced the structure of bacterial communities even in the absence of oil contamination. The 4°C/22 MPa and 4°C/22 MPaD treatments resulted in similar DGGE profiles. DNA sequencing (after 40 days of incubation) revealed that the diversity and relative abundance of bacterial genera were related to the presence or absence of oil contamination in the nonpressurized treatments. In contrast, the variation in the relative abundances of bacterial genera in the 4°C/22 MPa‐microcosms either contaminated or not with crude oil was less evident. The highest relative abundance of the phylum Bacteroidetes was observed in the 4°C/22 MPa treatment.

Studies on sandwich pipes, which comprise two concentric high strength steel tubes and a suitable annular material have shown good results due to their improved strength under external pressure and therefore they have been indicated as a good alternative for application in brazilian pre-salt scenario as gas and oil exportation pipelines. After installation on seabed a sandwich pipe can undergo mechanical damage caused by possible impacts of an anchor or some dropped heavy objects. When this happens, its strength under external pressure can be significantly reduced. This paper presents a numerical and experimental study of the reduced strength under external pressure (initiation pressure) of a damaged sandwich pipe. To this end, small scale sandwich pipe models were manufactured using steel tubes and PVDF in the annular space. Mechanical damages were simulated on the external surface of the models to collapse them under external pressure. The test results were compared to a three dimensional FE model simulating both the initiation pressure and the propagation pressure of the tested samples. A parametric study was carried out to analyze the sandwich pipe performance under damaged conditions.