This study examined the effectiveness of short-term, home-based occupational therapy guided by the Occupational Therapy Intervention Process Model for improving activities of daily living [ADL] with eight frail, older adults living in assistive living. A multi-method research approach was utilized to collect both quantitative and descriptive, qualitative data in the form of a retrospective examination of the participants' clinical records. The quantitative component was a within-subjects, repeated-measures analysis of participants' Assessment of Motor and Process Skills [AMPS] ADL motor and ADL process ability measures that revealed statistically significant improvement in ADL motor, but not ADL process abilities. The qualitative component was a content analysis of the clinical records. ADL baselines, goals, interventions and outcomes documented were analyzed. Improvement was noted in 77% of the written ADL goals. Results are discussed and recommendations were given for future research and documentation to improve the profession's ability to support evidence-based practice.
The paper describes a forensic investigation performed on severely corroded(pitted) chains recovered from a FSO mooring system in West Africa. During theinvestigation, it became apparent that a similar phenomenon had beenexperienced by JIP participants operating at other locations in West Africa, indicating that it may be a common problem deserving attention. The tentativeconclusion of the present investigation is that the large pits most likely canbe attributed to Microbiologically Influenced Corrosion (MIC). Subsequent pulltests of the chains to determine their residual strength gave surprisingly goodresults. Despite the large reduction in cross-sectional area, the effectivebreaking loads of the tested samples were found to be around 80-90% of thecatalogue minimum breaking load (MBL). The results also showed the chain linksto be resilient in strength. Introduction This paper summarizes some of the on-going work by the SCORCH JIP oncorroded/pitted chain links that were recovered from a Floating StorageOffloading (FSO) system based in West Africa. Although these links were inservice for only seven years, they experienced severe pitting corrosion (Figure 1) not noted previously in any available records. In some cases the pittingcaused a reduction in cross-sectional area of 35%. The chain links, whichexhibited strong signs of corrosion, were donated by the operator to the JIPfor research. They were shipped to Vicinay Cadenas in Spain for examination andtesting. This was performed according to the SCORCH JIP examination procedure. It is designed to gather all information required to perform a scientificanalysis in order to explain the observed corrosion. The FSO and its mooring system were installed in shallow water offshore WestAfrica in 1997. The external turret mooring system used a 6-leg all-chaindesign. The mooring chains were not isolated from the vessel hull, and thusmight have had some limited coverage by the Impressed Current CathodicProtection (ICCP) system on the vessel. The mooring legs consist of foursections, provided by three different vendors (numbered 1 to 3), as illustratedin Figure 2. Initially, there were three segments, a top and a bottom sectionprovided by the same vendor, with a catenary inflection weight (CIW) insertedto increase clearance and avoid clashing with the bow. Section 2 hangs from theCIW, serving as a clump weight. Section 3 was inserted between the CIW and theground chain when the FSO was relocated to a slightly deeper water depth. Allthree types of chain are 76mm in diameter. An early hypothesis theorized thatthe dissimilarity of the three materials was the root cause of the observedsevere pitting corrosion. The present investigation disproves thishypothesis During the annual chain survey in 2005, some visible corrosion on the chainsimmediately above waterline was noted. To determine the extent of metal loss, rope men were sent down to measure those chain links in air using a caliper. The survey showed that the in-air links had lost some cross-sectional area, apparently due to the well-known splash-zone effect [5]. Their remaining areaswere still within allowable limits at that time. During inspection in 2007, pitting corrosion was observed for the first time during a diver inspectionafter heavy marine growth was removed (see Figure 3). However, the extent andseverity of the problem was not evident at the time. In 2009, a decision wasmade to change out the mooring system. When all chains were recovered to terrafirma and marine growth was removed, it was found that the condition of thesubmerged chains was as poor as the splash-zone chains, although the damage wasof a different form.
For years operators have reported accelerated rates of corrosion in wire rope and chain in warmer waters. Mooring design codes specify corrosion endurance of these components predominantly based on experience from the colder waters of the North Sea. The scope of the SCORCH JIP was to investigate and characterize corrosion of steel chain and wire rope moorings for a wide range of operating Floating Production Units (FPUs) and Floating Production Storage and Offtake vessels (FPSOs) in warm waters. A database was compiled of detailed corrosion measurements of in-service and retired mooring chains and wire ropes from about 30 FPUs operating in warm waters off Asia, Africa and the Americas. A set of standardized procedures were developed for forensic examinations of retrieved chain and wire rope, including photogrammetry and laboratory measurements that allowed 3D reconstruction and statistical analysis of corroded surfaces. The database was complemented by destructive tensile tests of a number of samples in order to correlate the observed degradation with residual breaking load. The SCORCH JIP also investigated the impact of sea temperature, water velocity, depth and oxygenation, steel grade and chain and wire rope construction through over 750 sample and full-scale tests spanning 3.5 years at sites around Australia. Additional laboratory tests were conducted into Microbiologically Influenced Corrosion (MIC) and the combined effect of corrosion and wear of mooring chains. The SCORCH JIP has produced a series of findings with long-lasting implications for the industry, including detailed investigations of factors in corrosion such MIC, chain pitting, chain wear, wire rope blocking compound efficacy, and the effect of environmental and operating conditions. The SCORCH JIP has produced tabulated predictions for corrosion in varying temperatures, at positions in the mooring line and for nutrient levels that could encourage MIC. The predictions are underpinned by a large number of field experiments and results from operating FPUs, and are supplemented by detailed operational guidance and recommendations for maximizing mooring corrosion endurance.
The drag coefficient for long-slender structures that is typically provided in design guidance has been determined from test specimens of sufficient length that they are unaffected by the aspect ratio (L/D), whereby they are considered to be of “infinite” length. However, it is apparent from the literature that aspect ratio does have a significant non-linear effect at short L/D ratios. DNV provides guidance on the aspect ratio effect on the drag coefficient of a cylinder, for which no experimental source data has been cited. The DNV design guidance has wide usage in the offshore industry and merits critical evaluation. This paper critically reviews the literature and presents the results of a series of tow tank experiments performed by the authors. A series of tow tank tests of a surface-piercing cylinder has been undertaken using a range of aspect ratios as well as testing the effect of various end conditions, where the effects of VIV and ventilation has been deemed insignificant. Correlation of the various data sets of the literature and the experimental test programme provides the basis for developing an alternate design guidance curve for the effect of aspect ratio on the drag coefficient of cylinders.
Forensic investigations on severely corroded (pitted) chains recovered from the mooring systems of two FPUs in West Africa and Indonesia are described. During the course of the SCORCH JIP, it became apparent that a similar phenomenon had been experienced by other JIP participants indicating that it may be a common problem deserving attention. The conclusion of the present investigation is that the large pits most likely can be attributed to Microbiologically Influenced Corrosion (MIC). Where pitting occurred, the pit depth growth rate was found in instances to be up to 10 times the uniform corrosion rate, with pits distributed approximately uniformly but randomly around the link and the bar circumference. Destructive tensile tests of the samples indicated residual strength that was at worst 25% below as-manufactured estimated As-new Breaking Load (ABL). The correlation of loss of strength with loss of metallic area due to uniform and pitting corrosion indicated that breaking load cannot be treated simplistically, and requires more sophisticated consideration of the pit geometry and its location with respect to areas of high stress within the link.
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