scholarly journals MARINE EXPOSURE TESTS OF COCONUT TIMBER

CORD ◽  
1987 ◽  
Vol 3 (01) ◽  
pp. 34
Author(s):  
R. N. Palomar
Keyword(s):  
Sea Water ◽  
Coal Tar ◽  
Untreated Wood ◽  
Double Diffusion ◽  
Marine Structures ◽  
Sodium Dichromate ◽  
Diffusion Treatment ◽  
Pressure Method ◽  
Copper Arsenate ◽  
Hard Samples

Marine exposure tests of sawn coconut lumber were carried out for three years to determine the resistance, of treated coconut timber to marine borers.   The test panels measuzing 50 mm x 100 mm x 450 mm, were installed in sea water between October, 1981 and September, 1984. Results showed three promising treatments. These were the vacuum/pressure method using chromated copper arsenate, the modifted double diffusion treatment employing mixture of copper adphate, sodium dichromate and arsenic pentoxide, and the hot and cold bath treatment with coal tar creosote. The specimens treated by these preservative systems showed trace or slight sur­face infestation while the untreated wood panels indicated from deep and extensive infestation to failure due to attack of marine borers.   The perfomance of the treated medium density specimens appeared to be inferior than the hard samples indicating that only the latter materials should be used for marine structures.

The evolution of under-ice melt ponds, or double diffusion at the freezing point

1974 ◽  
Vol 64 (3) ◽  
pp. 507-528 ◽  
Author(s):  
Seelye Martin ◽  
Peter Kauffman
Keyword(s):  
Fresh Water ◽  
Sea Water ◽  
Freezing Point ◽  
Salt Water ◽  
Ice Sheet ◽  
Water Layer ◽  
Double Diffusion ◽  
Theoretical Models ◽  
Interfacial Region ◽  
Ice Melt

In an experimental and theoretical study, we model a phenomenon observed in the summer Arctic, where a fresh-water layer at a temperature of 0°C floats both over a sea-water layer at its freezing point and under an ice layer. Our results show that the ice growth in this system takes place in three phases. First, because the fresh-water density decreases upon supercooling, the rapid diffusion of heat relative to salt from the fresh to the salt water causes a density inversion and thereby generates a high Rayleigh number convection in the fresh water. In this convection, supercooled water rises to the ice layer, where it nucleates into thin vertical interlocking ice crystals. When these sheets grow down to the interface, supercooling ceases. Second, the presence of the vertical ice sheets both constrains the temperatureTand salinitysto lie on the freezing curve and allows them to diffuse in the vertical. In the interfacial region, the combination of these processes generates a lateral crystal growth, which continues until a horizontal ice sheet forms. Third, because of theTandsgradients in the sea water below this ice sheet, the horizontal sheet both migrates upwards and increases in thickness. From one-dimensional theoretical models of the first two phases, we find that the heat-transfer rates are 5–10 times those calculated for classic thermal diffusion.

Report on Thermoplastic Coal Tar Base Linings—A Report of NACE Unit Committee T-6A on Organic Coatings And Linings for Resistance to Chemical Corrosion, Prepared by Task Group T-6A-16 on Coal Tar Coatings*

CORROSION ◽  
1958 ◽  
Vol 14 (7) ◽  
pp. 35-37 ◽  
Keyword(s):  
Sea Water ◽  
Coal Tar ◽  
Chemical Properties ◽  
Surface Preparation ◽  
Fats And Oils ◽  
Organic Coatings ◽  
Physical And Chemical Properties ◽  
Chemical Corrosion ◽  
Physical And Chemical ◽  
And Chemical Properties

Abstract The relative resistances to various chemical environments are given for thermoplastic coal tar base linings. Media to which these linings are exposed include 11 acids, 5 alkalies, 2 oxidizing agents, 3 fats and oils, 5 gases, 7 solvents, 12 salts, as well as to sodium hypochlorite and to tap, distilled and sea water. Physical and chemical properties are listed for both hot and cold applied coatings. The application of coal tar base linings is considered in detail with special attention paid to such matters as coverage, surface preparation, priming, and application methods. 5.4.3

Controlling the failure of marine structures attached to the bottom of the sea under dynamic loading

2017 ◽  
Vol 8 (5) ◽  
pp. 565-575
Author(s):  
Hossein Nematiyan Jelodar
Keyword(s):  
Dynamic Load ◽  
Water Waves ◽  
Sea Water ◽  
Steel Structure ◽  
Internal Force ◽  
Dynamic Responses ◽  
Sea Waves ◽  
Marine Structures ◽  
The Caspian Sea ◽  
Content Type

Purpose Analysis of designing and controlling the failure of marine structures attached to the bottom of the sea under dynamic load obtained from the sea waves is one of the main engineering challenges in recent years. The circumstances of the onshore marine structures have their own complexity and the difficulty due to the effect of hydrodynamic factors and dynamic responses which are dominant in the marine environment. The paper aims to discuss these issues. Design/methodology/approach The structure elements are composed of the metal pipe with a length of 5 m, outside diameter of 20 cm and thickness of 1.5 mm. the failure control with a safety factor of 2 indicates the absence of the above marine structure failure. It has been diagnosed to be trustworthy and reliable. Findings In this study, the control of marine steel structure failure with the height of 60 m under the dynamic load of the sea water waves having sinusoidal shape in the Caspian Sea has been studied and analyzed. Originality/value In this paper, the minimum and maximum internal force and movement in six directions of freedom were obtained for each element. To analyze and control the failure, the combination of stresses caused by static and dynamic loads has been used. According to the regulation of 10-360-AISC, the control was conducted.

scholarly journals Effect of Natural Zeolite-Pozzolan on Compressive Strength of Oil-Polluted Concrete Marine Structures

2017 ◽  
Vol 2 (12) ◽  
pp. 623 ◽  
Author(s):  
Hamid Shahrabadi ◽  
Sina Sayareh ◽  
Hamed Sarkardeh
Keyword(s):  
Compressive Strength ◽  
Fresh Water ◽  
Natural Zeolite ◽  
Sea Water ◽  
Oil Pollution ◽  
Mix Design ◽  
Marine Structures ◽  
Natural Pozzolan ◽  
Fixed Amount ◽  
Strength Tests

Oil pollution into the concrete composed materials, leads to decrease the compressive strength of the constructed structure. In the present study, effect of using a natural pozzolan named Zeolite on concrete structures was tested in different marine conditions. A fixed amount of oil equal to 2% of sand weight was added as the pollution into the concrete composed materials. Natural Zeolite was added into the concrete instead of cement to the mix design with weight percentages of 10, 15 and 20. After preparing and curing, concrete specimens were placed into the three different conditions: fresh water, tidal, and sea water environments. Results of compressive strength tests showed that replacement of natural Zeolite instead of cement significantly increased compressive strength in comparison with control specimens, in all environments. Adding 20% natural Zeolite increased the compressive strength to its highest values about 60-85% higher than control specimens.

scholarly journals Katabatic wind influence on meltwater supply to fuel glacier–substrate interactions at the grounding line, Terra Nova Bay, East Antarctica

1999 ◽  
Vol 28 ◽  
pp. 272-276 ◽  
Author(s):  
A. Bouzette ◽  
R. Souchez
Keyword(s):  
Sea Water ◽  
Double Diffusion ◽  
Katabatic Wind ◽  
Local Production ◽  
Ice Shelf ◽  
Rock Outcrops ◽  
Katabatic Winds ◽  
Terra Nova Bay ◽  
Grounding Line ◽  
Wind Influence

AbstractThe co-isotopic composition, both in δDand in δ18O, of interbedded debris-rich and clear ice layers, thought to have been formed at the grounding line of Hells Gate Ice Shelf, indicates freezing by a double-diffusion effect between continental meltwater and sea water within a subglacial sediment. A source of meltwater is required to sustain the process, since the temperature of the bed is below the freshwater melting point. The most likely source is a surficially frozen meltwater lake.Rock outcrops, kept mostly snow-free by the action of katabatic winds, absorb solar radiation so local production of liquid water becomes possible in an area with year-round subfreezing air-temperature conditions. The meltwater accumulated in a marginal lake can eventually reach the subglacial substratum near a pinning point where the ice is relatively thin and fractured.

scholarly journals The Preservation of Fibre Ropes for Use in Sea-Water

1936 ◽  
Vol 20 (3) ◽  
pp. 643-654 ◽  
Author(s):  
W. R. G. Atkins ◽  
J. Purser
Keyword(s):  
Heavy Oil ◽  
Copper Sulphate ◽  
Untreated Control ◽  
Sea Water ◽  
Coal Tar ◽  
Tidal Basin ◽  
Initial Strength ◽  
Copper Oleate ◽  
Bacterial Decay ◽  
One Year

1. For the preservation of ropes the importance of the preservative against bacterial decay being also an internal lubricant for the rope fibres must be remembered.2. Tests have been carried out for one year in sea-water, which was much contaminated by sewage at times, under Plymouth Pier and in cleaner water of a tidal basin outside Plymouth Sound Breakwater for 10½ months, using 2-inch and 0-6-inch ropes respectively; the latter was manila, the former were manila, hemp, sisal and coir.3. The preservatives included cutch, cutch bichromate, cutch ammonia copper sulphate, coal tar distillates, including those of the Coalite process, also hardwood and softwood tars. The tars and tar oils were tried alone and mixed with copper soaps, naphthenate (Cuprinol and Shell products), oleate and resinate, also zinc and iron naphthenates (Cuprinol). The naphthenates and oleate are good lubricants.4. Very good results were obtained with green Cuprinol containing tar and with 10 per cent copper oleate in a light coal tar; slightly inferior were 10 per cent copper resinate in Coalite heavy oil or in creosote oil as now used largely in Plymouth; also 10 per cent copper oleate with 20 per cent of Coalite tar in Coalite neutral oil, b.p. 100–245° C, which i s a very cheap solvent. All these maintained the thin manila rope at or above 70 per cent of its initial strength after 10½ months; the untreated control was down to 13 per cent.

scholarly journals The vapour pressure and osmotic equivalence of sea water

1954 ◽  
Vol 33 (2) ◽  
pp. 449-455 ◽  
Author(s):  
R. A. Robinson
Keyword(s):  
Sodium Chloride ◽  
Vapour Pressure ◽  
Chloride Solution ◽  
Sea Water ◽  
Complex Solution ◽  
Sodium Potassium ◽  
Sodium Chloride Solutions ◽  
Pressure Method ◽  
Pressure Lowering ◽  
Calcium Magnesium

Sea water is a complex solution in which the principal ions are sodium, potassium, calcium, magnesium, chloride and sulphate. The vapour pressure (V.P.) of such a solution can be calculated approximately by making the assumption that each salt contributes to the vapour pressure lowering in amount proportional to its concentration, but such a calculation would ignore the interactions between the various ions. The theory of these interactions has been worked out only for very dilute solutions and it is, therefore, better to rely on direct experimental determinations. Measurements have now been made by the isopiestic vapour-pressure method (Robinson & Sinclair, 1934), in which samples of sea water are equilibrated with sodium chloride solutions until they have the same vapour pressure. The results are expressed in terms of chlorinities of sea water and molalities (moles per kilogram of H2O) of sodium chloride solution which have the same vapour pressure. It is hoped that the results will be of use to physiologists who have occasion to make up salt solutions equivalent to sea water.

scholarly journals Salinity and Isotope Analysis of Some Multi-Year Landfast Sea-Ice Cores, Northern Ellesmere Island, Canada

1988 ◽  
Vol 10 ◽  
pp. 63-67 ◽  
Author(s):  
Martin O. Jeffries ◽  
H. Roy Krouse
Keyword(s):  
Sea Ice ◽  
Sea Water ◽  
Growth Models ◽  
Isotope Analysis ◽  
Ice Cores ◽  
Double Diffusion ◽  
Ellesmere Island ◽  
Ice Growth ◽  
Water Stratification ◽  
Landfast Sea Ice

The salinity and isotope (18O, 3H) content of multi-year landfast sea-ice (MLSI) cores from northern Ellesmere Island, Canada, are examined. Salinity ranges from 0.01‰ to 4.54‰, and δ18O ranges from −23.8‰ to +0.7‰. Salinity and δ18O are linearly related, and tritium values generally exceed natural background levels. The results are evidence of ice growth associated with fresh-water / sea-water stratification below the ice. Salinity variations are cyclic and indicate a mean annual bottom accretion rate of 0.33–0.5 m a−1. Rather than signifying downward percolation of melt water from the surface, the ice δ values are a proxy measure of variations in salinity and 18O content of the water below the ice. Annual salinity layers are preserved in the absence of significant brine movement and ice deformation. The fast-ice environment appears to favour the maintenance of water stratification and growth of annual layers. It is suggested that ice growth in this environment is somewhat independent of thermodynamic sea-ice growth models; instead, ice growth by a double-diffusion process might account for the growth of MLSI beyond thicknesses normally encountered in undeformed multi-year pack-ice floes.

scholarly journals Marine ice recycling at the southern McMurdo Ice Shelf, Antarctica

2015 ◽  
Vol 61 (228) ◽  
pp. 689-701 ◽  
Author(s):  
Inka Koch ◽  
Sean Fitzsimons ◽  
Denis Samyn ◽  
Jean-Louis Tison
Keyword(s):  
Sea Water ◽  
Freezing Point ◽  
Diffusion Mechanism ◽  
Double Diffusion ◽  
Water Source ◽  
Water Masses ◽  
Ice Crystal ◽  
Ice Shelf ◽  
Frazil Ice ◽  
Water Composition

AbstractMarine ice accretes at the base of ice shelves, often infilling open structural weaknesses and increasing ice-shelf stability. However, the timing and location of marine ice formation remain poorly understood. This study determines marine ice source water composition and origin by examining marine ice crystal morphology, water isotope and solute chemistry in ice samples collected from the southern McMurdo Ice Shelf (SMIS), Antarctica. The measured co-isotopic record together with the output of a freezing model for frazil crystals indicate a spatio-temporally varying water source of sea water and relatively fresher water, such as melted meteoric or marine ice. This is in agreement with the occurrence of primarily banded and granular ice crystal facies typical for frazil ice crystals that nucleate in a supercooled mixture of water masses. We propose that marine ice exposed at the surface of SMIS, which experiences summer melt, is routed to the ice-shelf base via the tide crack. Here frazil crystals nucleate in a double diffusion mechanism of heat and salt between two water masses at their salinity-dependent freezing point. Recycling of previously formed marine ice facilitates ice-shelf self-sustenance in a warming climate.

Coal Tar Creosote Studies (Part 1–A Method for the Accelerated Evaluation Of Marine Wood Preservatives)

CORROSION ◽  
1958 ◽  
Vol 14 (6) ◽  
pp. 53-59
Author(s):  
T. R. SWEENEY ◽  
T. R. PRICE ◽  
R. A. SAUNDERS ◽  
SIGMUND M. MILLER ◽  
F. G. WALTON SMITH
Keyword(s):  
Sea Water ◽  
High Surface ◽  
Coal Tar ◽  
Average Molecular Weight ◽  
Volume Ratio ◽  
Test Method ◽  
Infrared Spectrophotometry ◽  
Differential Diffusion ◽  
Ordinary Temperature ◽  
Accelerated Leaching

Abstract A method is presented for comparing the marine borer resistance of creosoted wood with that of wood treated with fractions of creosote obtained by distillation, solvent extraction, etc. The test method is accelerated by the use of test panels having a high surface-volume ratio and by leaching replicates of panels prior to exposure to borer attack The mechanism of leaching in sea water and in accelerated leaching medium was studied by subjecting creosoted panels to four different treatments. The rate of leaching of material from the panels and the change in composition of the residual or leached creosote brought about by the differential diffusion of constituents from the wood were studied. Changes in composition were studied by means of distillation, average molecular weight and oxygen determinations, and infrared spectrophotometry. The standard accelerated leaching of creosoted panels brings about a differential loss of creosote constituents comparable to the loss of constituents occurring during leaching in sea water, but at a more rapid rate. The material remaining in creosoted panels after nine months of leaching at ordinary temperature had almost the same distillation pattern as the material remaining after one day of leaching at 80 C, both leachings being conducted in flowing water. Upon extrapolation, this correspondence equates 16 days of accelerated leaching with 12 years of leaching at ordinary temperature. 2.3.2

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