01/20.2022
01/20.2022
01/20.2022
01/20.2022
01/20.2022
01/20.2022
01/20.2022
01/20.2022
01/10.2022
01/10.2022
12/30.2021
12/24.2021
Before well repairing operation, it is often necessary to install the jack-up very close to the existing spudcan pits, which called footprints. The spudcan is prone to slide towards the footprint in this process, which can lead to damage of legs, jacking system and the hull structure. RPD (Rack Phase Difference) system can monitor the rack vertical phase difference of adjacent chord of truss type leg. In this paper, the RPD calculation principle is studied and an available analysis method of critical RPD applicable to spudcan sliding condition is obtained. The method can provide useful guidance to the designers and operators.
12/24.2021
This paper is to introduce the latest rule change proposal on improving the global elastic buckling requirements of Common Structural Rules for Bulk Carriers and Oil Tankers(CSR January 2020) of International Association of Classification Societies(IACS), which are carried out by IACS PT PH43. Based on general elastic orthotropic plate buckling theory, a set of new formulae regarding global elastic buckling capacity is proposed to replace the corresponding ones based on one-dimensional beam theory in CSR January 2020. Since the second order effect item of the stiffener bending moment is highly dependent on the new global elastic buckling capacity formula, the set of general stiffened panel ultimate capacity interactive formulae in CSR is recalibrated considering the effects due to Poisson correction, lateral pressure etc. Finally, a series of typical ship stiffened panels and some specially selected panels with slender stiffeners are calculated and compared with corresponding NLFEM results, which gives good agreement and verifies the correctness of the proposal. The rule change proposal has been incorporated in CSR January 2021 which takes into effect on July 1 2021.
12/24.2021
随着世界能源结构的调整及环保法令的不断收紧，LNG作为货物运输和船用燃料逐渐增多。中国作为造船大国向造船强国迈进过程中逐渐涉猎LNG运输船和LNG燃料动力船的建造项目，在此过程中，C型独立罐式船型存在自身优势，订单最多应用最广泛，首当其冲成为国内船企争相建造的船型，然由于缺乏实际建造经验，往往会遇到诸多实际生产施工问题，蒙受巨大损失。本文结合作者实际经历的几个LNG船建造检验项目积累经验，梳理了C罐船型建造过程中难度最大的罐体制造和船上安装重点和注意事项，为国内有意向进军LNG运输船和LNG燃料动力船的造船企业提供了参考，为保证LNG运输船和LNG燃料动力船建造质量提供了重要指导。
12/21.2021
As aft stern tube bearing
damages were reported quite often over the past years, which may pose threats to the safe operation of the
ships in the worst cases, shaft alignment has become a more heated topic than
ever before in the
industry. Root cause behind the damages is of interest to all parties involved.
In this regard, concerns have been paid to the “uncertainties” in the shaft
alignment process i.e. from the early shaft alignment design to final execution
of shaft alignment onboard and their contributions to the damage are discussed
as well in the paper. The uncertainties emphasized in the paper as sensitive
and crucial to the shaft alignment behavior are, to the best practice and
knowledge of CCS, identified and elaborated in a practical and effective way. The
uncertainties are mainly focused on: -the propeller hydrodynamic loads -alignment procedures for one stern tube bearing arrangement shafting -instability of viscosity of EALs (Environmentally acceptable
lubricants) against pressure
It is noted it is rather difficult
to get some uncertainties quantified precisely even with advanced computer
programs for the time being. One of the
best solutions to cope with the uncertainties is to improve the safety margin
in the early design stage by
reducing the mismatch angle between bearing surface and shaft. With the above in mind, a robust design of aft stern tube bearing,
e.g. optimized double slope bearing, as a countermeasure is presented in the late part of
the paper.
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