Hydrogen permeation through welded joints of S690QL steels at cathodic polarisation in sea water in the presence of SRB

The paper presents results of investigations performed by Devanatban-Stacbursky method of hydrogen permeation in sea water with sulphate reducing bacteria and for comparison in sterile conditions. The investigations were carried out for specimens of S690QL steel subjected to beat treatment simulating welding process and producing structures corresponding to structures occurring in beat affected zone. Cooling time in the range of temperature 800 - 500°C was 20, 60 and 100 s. Higher hydrogen concentration on the entry side of the specimen for all variants of welding beat cycles simulation was found in the presence of bacteria than in sterile conditions. In these last conditions differences between particular specimens are minimal especially in potential limits from +100 to -300 mV vs. Zinc electrode.