Port authorities are interested in the behavior of the civil engineering elements of port infrastructure, particularly with respect to the financial, technical, safety and environmental decisions to be taken during the life-time of the structures. It therefore follows that to avoid unexpected large-scale rehabilitation measures as a consequence of neglected periodic maintenance, a systematical planning and budgeting of maintenance activities is necessary. Life Cycle Management (LCM), and its precursor Whole Life Costing (WLC), will contribute to a realistic approach of maintenance policy, including decision-making, planning, budgeting and funding of inspection and repair activities during the life-time of port structures. PIANC PTC-II Working Group 31 (WG31) was constituted in 1993 to review and offer guidance on the use of LCM for new and existing structures in ports and published the LCM Report in 1998. In accordance with the LCM Report, the significance and outline of LCM, the outline and example of WLC and the case study of LCM are presented.
Intergranular corrosion (IGC) and intergranular stress corrosion cracking (IGSCC) of the recrystallized Alloy 182 weld metal containing 0.05%C have been investigated. Cold rolled Alloy 182 was recrystallized by electric furnace heating or by YAG (Yttrium-Aluminum-Garnet) laser irradiation. IGC resistance and IGSCC resistance were evaluated by Streicher test (JIS G 0572) and by Crevied Bent Beam test in the 288°C hot water respectively. It was observed that the 60% cold rolled Alloy 182 is occupied by the recrystallized gains after the electric furance heating at 800 to 900°C, and the recrystallized Alloy 182 is excellent in IGC resistance. By YAG laser irradiation, surface recrystallized layer of about 400 to 500μm thickness can be formed on the cold rolled Alloy 182. Corrosion resistance of the surface recrystallized Alloy 182 is also excellent, because of the granular Cr-rich carbides distribution in the recrystallized grains.
Surfaces of the copper tubes after the four-year field test have been investigated by the optical microscope, SEM, EDS and EPMA. The upper side of a half-cut tube has many greenish-blue corrosion products. Optical micrographs revealed that there are many moundless pits in the centers of these corrosion products. These moundless pits were classified into two types. One type is “open type” which has an open entrance of the pit, another is “closed type” which is totally covered with a thin film on the entrance of the pit. The thin film on the closed type pit is fragile, so cracks are found on the films of some closed type pits. This observation suggests that the open type pit is formed as a result of breaking the thin film of closed type pit. EPMA analysis revealed that the film was mostly composed of Si. The lower side of a half-cut tube was totally covered with greenish-yellow corrosion products. EDS analysis revealed the presence of iron in these corrosion products. Pitting corrosion has not been observed on the surface of the lower side covered with the greenish-yellow corrosion products. These facts indicate that iron contributes to the prevention of the moundless pits.
Corrosion tests were conducted to select materials for the decomposition reactor using the SCWO process for organic wastes from nuclear plant. Examination conditions were determined, as Condition 1:400°C, 28.5MPa in 2%H2SO4 solution with 2%H2O2 and Condition 2:450°C, 30MPa in 1.2%H2SO4 solution with 2%H2O2, assuming the decomposition of ion exchange resin that generates sulfate ion. Firstly, in order to select candidate materials, short-period screening tests were carried out on various high corrosion resistance materials under Condition 1. Then, long-period corrosion tests were carried out for Ta, Ti and Ti alloys under Condition 2 to estimate the corrosion rate and to evaluate the applicability. The results of these tests indicate that the corrosion resistance of Ti alloys is sufficient to be applied as reactor materials for the organic waste decomposition systems using SCWO process. The structure and materials of pilot plant of SCWO for organic waste decomposition was determined from corrosion test results.
In the previous paper, two types of corrosion tests (so-called erosion-corrosion and flow velocity difference induced corrosion) were conducted on various beryllium-copper-nickel alloys. Of the alloys tested, the 30CuNi and Be30CuNi alloys performed the best. However, a 70CuNi and a Be70CuNi alloy showed a performance comparable to the level of 30CuNi, provided the flow velocity over the alloy surface was maintained within a certain velocity range. The anti-fouling performance of the above alloys was determined by using mussels as a model foulant. As a result the 70CuNi and the Be70CuNi alloys showed the best anti-fouling performance even though it was less soluble than pure Cu metal or BeCu alloy. This is due to the fact that mussels avoided regions that contained high concentrations of copper ions, located in the gaps of the corrosion products film in those alloys. Thus, the 70CuNi and the Be70CuNi alloys were judged to be the most useful alloy, since it had an excellent anti-fouling property as well as satisfactory anti-corrosion properties.