همایش ملی صنایع دریایی ایران
سال:1392 | دوره:16 |تعداد مقالات:12

THE AIM OF THIS ARTICLE IS TO INVESTIGATE THE MAIN STAGES OF DESIGNING OFFSHORE OIL/GAS PIPELINE SYSTEMS. TO PERFORM THE WORK, DESIGN STEPS DIVIDED INTO THREE MAIN CATEGORIES INCLUDING FLOW ASSURANCE, MATERIAL SELECTION AND MECHANICAL DESIGN. THEN, MAIN OBTAINED DATA FROM EACH SECTION SUCH AS INTERNAL DIAMETER, WALL THICKNESS, MATERIAL GRADE, MAXIMUM OPERATING PRESSURE/TEMPERATURE WERE SPECIFIED. IN ORDER TO OPTIMIZE AND FINALIZE THE CALCULATED PARAMETERS, INTERACTION BETWEEN MATERIAL SELECTION AND FLOW ASSURANCE SECTIONS WITH MECHANICAL DESIGN SECTION WERE CONSIDERED. IN THIS REGARD, PARTICULAR ATTENTION ON PIPELINE MECHANICAL DESIGN SUB-SECTIONS SUCH AS WALL THICKNESS CALCULATION, STABILITY CALCULATION, THERMAL EXPANSION, FREE SPAN AND PIPELINE INSTALLATION ANALYSIS AS WELL AS RISER AND SPOOL STRESS ANALYSIS WAS PERFORMED. IN ORDER TO HAVE BETTER VIEW ABOUT DESIGN STAGES AND RELEVANT INTERACTIONS, A CASE STUDY WAS RUN FOR 18" CLADDED INFIELD OFFSHORE PIPELINE SYSTEM LOCATED IN PHASE1 OF SOUTH PARS FIELD AND OBTAINED RESULTS WERE VERIFIED.

THIS PAPER DISCUSSES ABOUT AN OPTIMUM HYDRODYNAMIC SHAPE OF STERN OF SUBMARINE IN MINIMUM RESISTANCE POINT OF VIEW. SUBMARINES HAVE TWO MAJOR CATEGORIES FOR HYDRODYNAMIC SHAPE: TEAR DROP SHAPE AND CYLINDRIC MIDDLE BODY SHAPE. HERE, SUBMARINE WITH PARALLEL (CYLINDRICAL) MIDDLE BODY ARE STUDIED BECAUSE, THE MOST OF NAVAL SUBMARINES AND ROVS HAVE CYLINDRIC MIDDLE BODY SHAPE. EVERY HULL SHAPE, HAVE THREE PARTS: BOW, CYLINDER AND STERN. THIS PAPER WANTS TO PROPOSE AN OPTIMUM STERN SHAPE BY CFD METHOD AND FLOW VISION SOFTWARE. MAJOR PARAMETER IN HYDRODYNAMIC DESIGN OF STERN IS WAKE FIELD (VARIATION OF FLUID VELOCITY) AND RESISTANCE. THE FOCUS OF THIS PAPER IS ON THE RESISTANCE AT FULLY SUBMERGE MODE WITHOUT FREE SURFACE EFFECTS.FIRSTLY, ALL AVAILABLE EQUATIONS FOR THE STERN SHAPE OF SUBMARINE ARE PRESENTED. SECONDLY, FOR ALL EQUATIONS OF SHAPES, CFD ANALYSIS HAS BEEN DONE. IN ALL MODELS, THE VELOCITY, DIMENSIONS OF DOMAIN, DIAMETER, BOW SHAPE AND THE TOTAL LENGTH (BOW, MIDDLE AND STERN LENGTH) ARE CONSTANT.

ONE OF THE GREATEST TECHNOLOGICAL CHANGES AND DEVELOPMENTS IN INTERNATIONAL TRANSPORTATION IS THE FOUNDATION AND PREVALENCE OF CONTAINERS IN THIS AREA. NOWADAYS, OPERATORS OF TRANSPORTATION AND TRADE USE CONTAINERS BECAUSE OF THEIR HIGH STRENGTH, THE ABILITY TO STORE THEM ON TOP OF EACH OTHER ON THE SHIP, ITS WATER PROOF MATERIAL, NO NEED FOR A COVERED STORAGE ROOM, THE FACT THAT IT CAN EASILY AND QUICKLY BE LOADED ONTO A SHIP, TRUCK, OR TRAIN, FAST TRANSPORTATION, MINIMUM CARGO DAMAGE DURING CARGO OPERATION & TRANSPORTATION, ITS SECURITY AGAINST THIEVES, THEY ARE REUSABLE, PACKAGES CAN BE SORTED LIKE TRAYS, AND THEY CAN BE USED ON REFRIGERATED SHIPS SINCE EACH CONTAINER HAS A SET OF GOODS WITH A PACKING LIST AND THE ACCUMULATION OF THESE GOODS IN ONE LARGE PACKAGE DECREASES THE NUMBER OF PACKING LISTS AND AT THE SAME TIME DECREASES THE NUMBER OF CUSTOMS DOCUMENTS. CONSIDERING THIS TOPIC, THE DANGERS RELATED TO THE SHIP’S STABILITY WHILE LOADING AND DISCHARGING CONTAINERS IN PORTS WILL BE REVIEWED AND SOLUTIONS WILL BE BROUGHT UP.THE RESULTS OF THIS STUDY CAN HELP PORT AND SHIP WORKERS DECREASE THESE DANGERS WHILE LOADING AND DISCHARGING CONTAINERS IN PORTS.

THE OBJECTIVE OF PRESENT PAPER IS TO ANNOUNCE AN APPROPRIATE UNIDIRECTIONAL WAVE SPECTRUM MODEL FOR CHABAHAR BAY AT THE NORTH OF OMAN SEA. PRIMITIVE INVESTIGATIONS HAD BEEN CONDUCTED ON THE FIELD DATA, SHOWING THAT THEY MAY SUFFER UNPHYSICAL DATA. HENCE, IN THE FIRST STEP, USING KNOWN METHODS THE ERRORS WERE DISCOVERED AND MODIFIED. THEN, THE RESEARCH IS CONCENTRATED ON APPRAISAL OF STANDARD WAVE SPECTRUM MODELS IN THE REGION. WAVE SPECTRUM MODELS SUCH AS JONSOWAP, PM, OCHI-HUBBLE AND ITTC INDICATED THAT CONSIDERING STANDARD COEFFICIENT, OCHI-HUBBLE SPECTRUM IS NOT APPROPRIATE FOR FIELD SPECTRUMS WITH TWO PEAKS. ALSO IT WAS SEEN THAT ITTC MODEL DEMONSTRATES A GREAT FIT WITH FIELD SPECTRUMS THAT HAVE ONE PEAK. THEN BY USING GRG NONLINERA METHOD COEFFICIENTS WERE PROPOSED FOR ITTC AND OCHI- HUBBLE MODELS IN ORDER TO INCREASE THEIR ACCURACY.

CONSOLIDATION SETTLEMENT ANALYSIS IS A NECESSARY PART OF THE DESIGN PROCESS FOR SUCTION CAISSONS. HOWEVER IT IS A COMPLEX TASK SINCE SOIL VOLUME IMPORTANT FOR SETTLEMENT ANALYSES IS MAINLY AFFECTED BY THE INSTALLATION PROCESS. CONSOLIDATION SETTLEMENTS HAVE BEEN FOUND TO BE THE CRITICAL DESIGN CRITERION IN SEVERAL PARTICULAR SUBSEA PROJECTS. THEREFORE PERFORMING ADEQUATE AND COMPREHENSIVE ANALYSIS SEEMS INEVITABLE. THE FINITE ELEMENT METHOD (FEM) HAS BEEN USED TO CONSIDER THE CONSOLIDATION PROCESS AFTER COMPLETED INSTALLATION OF THE SUCTION CAISSON. STUDYING OF SHEAR STRENGTH INCREASE WITH TIME ALONG THE SKIRTS HAS BEEN DONE. DURING CONSOLIDATION SETTLEMENT, DISSIPATION OF EXCESS PORE PRESSURE RESULT IN HIGHER EFFECTIVE STRESSES. CONSEQUENTLY THE MODELED CAISSON UNDRAINED SHEAR STRENGTH INCREASES. ADEQUATE MODELING OF THE CHANGES IN THE INTERFACE ZONES ADJACENT TO THE CAISSON WALLS DURING CONSOLIDATION IS VITAL FOR CORRECT PREDICTION OF LONG TERM SETTLEMENTS. MODELED UNDRAINED SHEAR STRENGTH HAVE HUGE IMPACT ON THE ANALYSIS RESULTS DUE TO DIFFERENT MOBILIZATION OF THE SURROUNDING SOIL. APPROPRIATE EVALUATION OF SOIL STRUCTURE INTERACTION IS ESSENTIAL TO ASSESS THE RELIABILITY OF THE ANALYSIS. THE RESULTS WERE FOUND TO BE REASONABLE WITH RESPECT TO FINAL CONSOLIDATION SETTLEMENTS AND DEVELOPMENT OF MOBILIZED SHEAR STRENGTH WITH TIME.

BECAUSE OF REDUCED FUEL CONSUMPTION, INCREASING OF THE FUEL COSTS AND GROWING OF THE ENVIRONMENTAL CONCERNS, REDUCED ENVIRONMENTAL POLLUTION AND INCREASE IN LIFE OF A VESSEL’S PROPULSION SYSTEM, LED ENERGY CONSUMPTION TO BECOME ONE OF THE MOST IMPORTANT SUBJECTS OF THE MODERN AND DEVELOPED COUNTRIES AND HYBRID SYSTEM HAS BEEN APPLIED ON VESSELS. USE OF TWO OR MORE ENERGY SOURCES IS THE MAIN PROPERTY OF A HYBRID SYSTEM. DIFFERENT COMBINATIONS OF INTERNAL COMBUSTION ENGINES (ICE), STEAM TURBINE (ST), GAS TURBINE (GT), FUEL PILES WITH ELECTRIC MOTOR (EM) CAN BE USED FOR DIFFERENT TRANSPORTATION VEHICLES. A HYBRID VESSEL SYSTEM CAN BE EITHER COMBINATION OF DE AND EM OR GT AND EM. SO EACH ONE OF CODLOD/ CODLAD/ CODLOG/ OR CODLAG SYSTEMS CAN BE CALLED A HYBRID SYSTEM. A FRIGATE (AS A VESSEL) NEEDS DIFFERENT SPEEDS IN DIFFERENT POSITIONS, CASES AND SITUATIONS. EVERY SITUATION NEEDS DIFFERENT MODES FOR A VESSEL. SO THE TYPICAL HYBRID OPERATION MODES (PTI BOOSTER MODE, GENERATOR MODE (OR PTO-MODE), ELECTRICAL MODE AND ELECTRICAL CROSS-CONNECTION MODE (ELECTRIC SHAFT) WILL BE INTRODUCED.

IN THIS PAPER, A THREE DIMENSIONAL NUMERICAL MODELLING IS PRESENTED TO OBTAIN STRUCTURAL RESPONSE OF TWO TYPES OF WOVEN FABRICS SUBJECTED TO HIGH VELOCITY IMPACT LOADING. THE KEVLAR AND E-GLASS FIBERS ARE VERY PROMISING MATERIAL IN MARINE INDUSTRIES DUE TO UNIQUE MECHANICAL PROPERTIES SUCH AS IMPACT ENERGY ABSORPTION AND HIGH STRENGTH TO WEIGHT RATIO. USING FINITE ELEMENT PACKAGE OF ANSYS EXPLICIT DYNAMIC 15, THE PERFORMANCE OF KEVLAR FABRIC LAYER AGAINST OF HIGH VELOCITY IMPACT OF SPHERICAL PROJECTILE IN COMPARISON OF E-GLASS FABRIC LAYER IS INVESTIGATED. THE FOCUS OF THIS PAPER IS INVESTIGATING THE EFFECTS OF FABRIC TYPE AND BOUNDARY CONDITIONS ON THE IMPACT RESPONSE OF WOVEN FABRIC USED IN MARINE OPERATIONS. THREE TYPES OF BOUNDARY CONDITIONS ARE APPLIED TO THE SIMULATED FABRIC MODELS AND STRUCTURAL MANNER AND VELOCITY REDUCTION OF PROJECTILE AFTER IMPACT IS INVESTIGATED. FOR ACCURATE SIMULATION OF INTERACTIONS OF YARNS IN FABRIC, DYNAMIC FRICTION BETWEEN YARNS IS CONSIDERED. FINITE ELEMENT ANALYSIS IS APPLIED FOR MODELS PRIOR TO INITIATION OF FAILURE IN WOVEN FABRICS. RESULTS SHOW THAT THE HIGH VELOCITY IMPACT PERFORMANCE OF KEVLAR WOVEN FABRIC IS VERY DIFFERENT FROM E-GLASS WOVEN FABRIC.

THIS PAPER PRESENTS SOME OF THE BASIS AND CONCEPTS OF SUBMARINE SHAPE DESIGN. USUALLY, THERE ARE SOME QUESTIONS ABOUT THE ORIGINS AND REASONS OF THE SELECTION OF OVERALL HYDRODYNAMIC SHAPE, THE DIAMETER AND LENGTH, THE BOW AND STERN SHAPE. THIS PAPER USES CFD METHOD FOR ANALYSIS OF SIX DIFFERENT MODEL OF SUBMARINE. THE RESISTANCE COEFFICIENTS OF EACH SHAPE ARE PRESENTED AND COMPARED SO THAT COULD UNDERSTAND THE REASON OF SUBMARINE SHAPE SELECTION WITH TAPERED STERN AND CURVED BOW. THE FOCUS OF THIS PAPER IS ON THE CYLINDRICAL MIDDLE BODY SUBMARINE SUCH AS THE MOST OF NAVAL SUBMARINES AND ROVS.DETERMINATION OF DIAMETER AND LENGTH OF SUBMARINE IS RELATED TO THE L/D RATIO THAT IS SOMEWHAT DISCUSSED HERE BY CFD MODELING.THE OUTLOOK OF THIS PAPER IS ON THE NAVAL SUBMARINES, AND SOME USEFUL NOTES ARE PRESENTED IN THIS FIELD.THE TOOLS OF CFD MODELING IS FLOW VISION (V.2.3) SOFTWARE THAT IS KNOWN AS A SKILLED SOFTWARE IN CFD MODELING.

IN CURRENT STUDY, NUMERICAL AND EXPERIMENTAL INVESTIGATIONS ABOUT WATER ENTRY PROBLEM WERE CONDUCTED FOR A SYMMETRICAL WEDGE. THE WATER ENTRY PROBLEM FOR DIFFERENT GEOMETRIES IS ONE OF THE CLASSICAL METHODS FOR DETERMINATION OF PRESSURE DISTRIBUTION AND LOADS AROUND THE HULL OF MARINE VEHICLES. THESE DATA CAN BE USED FOR OPTIMUM STRUCTURAL DESIGN OF VESSELS PARTICULARLY FOR HIGH-SPEED CRAFTS, WHICH ARE VERY SENSITIVE ABOUT THE WEIGHT. IN ADDITION, THE QUANTITY OF LOAD CAN BE CONSIDERED IN THE EQUATION OF MOTION FOR ANALYZING THE SEAKEEPING PERFORMANCE OF SUCH VESSELS.IN THIS RESEARCH, THE NUMERICAL ANALYSIS OF FREE FALLING WEDGE WITH 30O DEADRISE WITH CONSTANT WEIGHT WAS DONE AND FOR VALIDATION OF RESULTS, IT WAS FOLLOWED BY EXPERIMENTAL TESTS. THE OUTPUTS OF THIS STUDY CONSIST OF SOME GRAPHS FOR COMPARISON OF TRENDS FOR PRESSURES RESPECT TO IMPACT TIME, WHICH CAN BE USED FOR SIGNIFICATION OF LOADS ON HULLS DURING THE WATER ENTRY PHASE.

CORROSION HAS LONG BEEN ONE OF THE BIGGEST PROBLEMS IN THE MARITIME, OIL AND GAS INDUSTRIES. CORROSION NOT ONLY CAUSE HIGH REPAIR COSTS, BUT ALSO TO STOP PRODUCTION AT THE TIME OF REPAIR AND SAFETY ISSUES ARE THE ENORMOUS DAMAGE IT CREATES.CONSTRUCTION AND OPERATION OF OFFSHORE PRODUCTION FACILITIES IS TREMENDOUSLY EXPENSIVE. THE CONSEQUENCES OF AN OFFSHORE CORROSION FAILURE CAN BE DEVASTATING. FOR THESE REASONS, CATHODIC PROTECTION HAS BECOME A UNIVERSALLY APPLIED TECHNIQUE FOR MITIGATING CORROSION ON SUBSEA PIPELINE AND PRODUCTION FACILITIES. NEWLY DEVELOPED SURVEY METHODS, COMBINED WITH INNOVATIVE DESIGN SOFTWARE AND LOW COST HARDWARE, ARE HELPING TAKE THE PAIN OUT OF ASSET LIFE EXTENSION FOR MANY OPERATORS WORLDWIDE. THE PURPOSE OF THIS PAPER IS TO PRESENT AN OVERVIEW OF SUBSEA CATHODIC PROTECTION AND CORROSION CONTROL SURVEY TECHNIQUES IN USE TODAY FOR MONITORING AND MAINTENANCE OF OFFSHORE PIPELINES AND PLATFORMS.

THIS PAPER PRESENTS SOME OF THE EQUATIONS OF THE BARE HULL FORM OF THE SUBMARINES. DESIGN OF OVERALL HYDRODYNAMIC SHAPE, IS AN IMPORTANT START POINT OF SUBMARINE DESIGN PROCESS, SPECIALLY IN HYDRODYNAMICS AND GENERAL ARRANGEMENT. THIS PAPER HAS COLLECTED THE MOST FAMOUS OF THESE EQUATIONS THAT ARE COMMON PRACTICE IN REAL NAVAL SUBMARINES AND ROVS. IN NAVAL ARCHITECTURE DESIGN, THERE ARE SOME MAIN CRITERIA FOR SELECTING AN OPTIMUM HULL FORM FOR A SUBMARINE, THAT IS HINTED IN THIS PAPER. THIS PAPER IS A REVIEW STUDY.

IN CURRENT RESEARCH TWO EXISTING PILE THROUGH LEG JACKET PLATFORMS OF FOROUZAN OIL AND GAS ZONE ARE MODELED WITH SKIRT PILES IN SACS SOFTWARE TO COMPARE THEIR STRUCTURAL BEHAVIOR, WEIGHT, CONSTRUCTABILITY, MAINTAINABILITY, REMOVAL COSTS AND OTHER PARAMETERS TO FIND WHICH DESIGN METHOD IS MORE BENEFICIAL FOR FOROUZAN OIL AND GAS ZONE. MODELING AND ANALYSIS ARE DONE BASED ON ORIGINAL JACKETS DESIGN CRITERIA AND SPECIFICATION TO REACH MORE REALISTIC RESULTS. SELECTING DESIGN AND FABRICATION METHOD IN OFFSHORE PROJECTS ARE CLOSELY RELATED TO CONTRACTORS’ EQUIPMENT AND EXPERIENCE AND ALSO EACH METHOD HAS ITS OWN BENEFICIAL AND ADVANTAGEOUS POINTS WHICH CAN LEAD TO USE THEM IN SPECIFIC PROJECTS. THESE METHODS DISCUSSED COMPREHENSIVELY IN CURRENT PAPER HOWEVER FOR THIS PARTICULAR SITE AND ITS ENVIRONMENT, THE ANALYSES INDICATE THAT USING SKIRT PILE METHOD MAY RESULT IN MORE OPTIMIZED AND LIGHTER STRUCTURES WHICH ARE EASIER TO INSTALL AND REMOVE AND MORE STRUCTURAL BENEFITS AND LOWER COSTS CAN BE ATTAINED IN THIS ZONE.