Observed Wave Actions on Norwegian Semi-Submersible and TLP Decks

2018 ◽  
Author(s):  
Arne Kvitrud ◽  
Anders H. Løland
Keyword(s):  
Physical Appearance ◽  
Weather Conditions ◽  
Wave Impact ◽  
Drilling Rig ◽  
Common Causes ◽  
Horizontal Wave

Waves have impacted decks on Norwegian semi-submersibles (semis) and TLPs several times. However, it did not get necessary attention before two accidents in 2015. In 2015, a wave impact caused a fatality and four injured on the semi-submersible drilling rig COSLInnovator. The same year, a wave washed away gratings on Scarabeo 8, causing a man to fall 13.5m to the sea. When examining our records, we found 29 reported incidents related to waves in deck on 17 platforms from 2000–2017. 27 of the wave actions were mainly directed upward and the remaining two were mainly horizontal wave hits. We describe each incident and the circumstances. We discuss common causes related to weather conditions and the physical appearance of the platforms. Further, we summarise design and operational precautions taken by the industry.

Prediction of Wave-in-Deck Forces on Fixed Jacket-Type Structures Based on CFD Calculations

2008 ◽  
Author(s):  
Benedicte Brodtkorb
Keyword(s):  
Initial Phase ◽  
Central Element ◽  
Load Level ◽  
Impact Loads ◽  
Extreme Waves ◽  
Original Design ◽  
Wave Impact ◽  
Cfd Simulations ◽  
Simplified Method ◽  
Horizontal Wave

The original design requirement for positive air gap is no longer fulfilled for a number of jacket-type structures still in production. When extreme waves impact the deck, the total loads on the structure are increased significantly, so accurate prediction of wave-in-deck forces is a central element in structural reassessment. Simplified methods for evaluating maximum horizontal and vertical loads are useful in an initial phase. In this study, we compare numerical prediction using CFD with the simplified API method for horizontal wave-in-deck load. The global wave impact loads for 0° head-on and 45° oblique waves are calculated for various deck configurations, all heavily equipped (solid). The effect of current is also addressed. In the case of no current, we found that the CFD simulations generally display a reasonable load level compared with the API load method. However, the CFD calculations indicate that the simplified method should be used with care for situations with large upwelling of water and decks with multiple deck girders. A simplified method for predicting vertical wave-in-deck loads on solid decks is developed. The method, first published in DNV-RP-C205, aims to be useful in an initial phase of reassessment.

Investigation and Prediction of Wave Impact Loads on Ship Appendage Shapes

2007 ◽  
Author(s):  
Anne M. Fullerton ◽  
Thomas C. Fu ◽  
David E. Hess
Keyword(s):  
Wave Height ◽  
Impact Force ◽  
Design Guidelines ◽  
Impact Loads ◽  
Wave Steepness ◽  
Wave Impact ◽  
Ship Structures ◽  
Impact Forces ◽  
Hull Structure ◽  
Horizontal Wave

Navy fleet problems with damage to hatches and other appendages after operation in high sea states suggest that wave impact loads may be greater than the current design guidelines of 1000 pounds per square foot (48 kilopascal) (Ship Specification Section 100, General Requirements for Hull Structure and Guidance Manual for Temporary Alterations, NAVSEA S9070-AA-MME-010/SSN, SSBN). These large impact forces not only cause damage to ships and ship structures, they can also endanger the ship’s crew. To design robust marine structures, accurate estimates of all encountered loads are necessary, including the wave impact forces, which are complex and involve wave breaking, making them difficult to estimate numerically. An experiment to investigate wave impact loads was performed at the Naval Surface Warfare Center, Carderock Division in 2005. During this experiment, the horizontal and vertical loads of regular, non-breaking waves on a 12 inch (0.305 m) square plate and a 19.75 inch (0.5 m) diameter horizontal cylinder were measured while varying incident wave height, wavelength, wave steepness, plate angle and immersion level of the plate and cylinder. Wave heights of up to 1.5 feet (0.46 m) were tested, with wavelenghs of up to 30 feet (9.1 m). In all cases, the horizontal wave impact force increased with wave steepness. For some angles, the horizontal wave impact force increased with greater submergence. A feed-forward neural network (FFNN) developed by Applied Simulation Technologies was used to predict the horizontal forces measured during the experiment based on the values of wave height, wavelength, wave steepness, plate angle and immersion level of the plate and cyclinder. A FFNN is a computational method used to develop nonlinear equation systems that use input variables to predict output variables. Predictions of forces from the FFNN compare well with the experimental data, and may be useful in future design of ships and ship structures.

Study on the Influence of Heat Wave and Cold Wave Characteristics and Vulnerable Areas in Busan, Ulsan and Gyeongsangnam-do

2020 ◽  
Author(s):  
Miyeong Jo ◽  
Jiyeun Ye ◽  
Jihye Yun ◽  
Jaeeun You ◽  
Juyeong Kim ◽  
...  
Keyword(s):  
Heat Wave ◽  
Heat Waves ◽  
Weather Conditions ◽  
Cold Weather ◽  
Current Status ◽  
Maximum Temperature ◽  
Cold Wave ◽  
Observation Data ◽  
Physical Damage ◽  
Wave Impact

<p>The frequency of extreme weather phenomena such as heat wave and cold wave has increased recently, and the intensity of weather has been strengthened, resulting in human and physical damage. The Republic of Korea has been working to reduce damage since 2018 by including heat and cold waves in natural disasters. The Korea Meteorological Administration (KMA) also provides impact-based forecasts, which requires research that suits local characteristics. In this study, weather observation data related to the summer heat wave in Busan, Ulsan and South Gyeongsang Province was analyzed to determine the weather conditions for the heat wave. In addition, in relation to the heat wave impact-based forecast that was provided regularly in 2019, the heat threshold was applied by comparing the current status of the heat-related patients with the maximum temperature, the number of consecutive days of the heat wave and the current status of the heat-related patients. The impacts of heat waves in different fields were analyzed, including livestock waste, fisheries food damage, and heat damage by crops. The cold wave also analyzed the number of days of cold wave in Busan, Ulsan, and South Gyeongsang Province by comparing the lowest temperature with the current status of cold-related patients. The impacts of cold weather conditions such as wind direction, wind speed and the number of consecutive days of the cold wave were also analyzed. Further, for regular provision of cold wave impact-based forecast to be implemented in 2020, the impacts of each cold wave vulnerable areas suitable for Busan, Ulsan, and South Gyeongsang Province were analyzed and referred to when applying cold wave thresholds.</p>

Processing method and governing parameters for horizontal wave impact loads on a semi-submersible

2020 ◽  
Vol 69 ◽  
pp. 102673 ◽  
Author(s):  
Yinghao Guo ◽  
Longfei Xiao ◽  
Xiaoqing Teng ◽  
Yufeng Kou ◽  
Jiancheng Liu
Keyword(s):  
Processing Method ◽  
Impact Loads ◽  
Wave Impact ◽  
Horizontal Wave

scholarly journals Analysis of the road accident rate in Lubelszczyzna and Podkarpacie

2018 ◽  
Vol 19 (6) ◽  
pp. 322-326
Author(s):  
Edyta Zielińska
Keyword(s):  
Traffic Safety ◽  
Weather Conditions ◽  
Road Accident ◽  
National Average ◽  
The South ◽  
Accident Rate ◽  
Traffic Incidents ◽  
The Road ◽  
South Eastern ◽  
Common Causes

The article assesses two provinces of the south-eastern Poland, i.e. Lublin Province and Podkarpackie, taking into account the number of accidents, persons injured and the persons who caused the accident. In addition, the most common causes of such negative traffic incidents, i.e. speeding or weather conditions, are listed. For better evaluation of the safety on the roads of Lubelszczyzna and Podkarpacie, the road accident rate in the said provinces was compared with the national average. Also, the actions taken to improve the traffic safety on Polish roads were presented.

Experimental and Numerical Study of Horizontal Wave Impact Loads for a Semi-Submersible Drilling Unit

2019 ◽  
Author(s):  
Joo-Sung Kim ◽  
Seon Oh Yoo ◽  
Hyun Joe Kim ◽  
Jong Hun Lee ◽  
So Lyoung Han ◽  
...  
Keyword(s):  
Cfd Simulation ◽  
Numerical Study ◽  
Vertical Direction ◽  
Maximum Pressure ◽  
Impact Loads ◽  
Wave Impact ◽  
Vertical Side ◽  
Horizontal Wave ◽  
Drilling Unit ◽  
Run Up

Abstract A semi-submersible drilling unit model was tested to estimate horizontal wave impact loads on vertical side of deckbox following the procedure recommended by DNVGL OTG-14. The present model test data show that there is clear difference in the relationships between upwell and horizontal wave impact pressure between near column/pontoon and around centerline. Near column and pontoon, not only is the maximum pressure much lower but the pressure increases more smoothly to its maximum value, compared to those of centerline. CFD simulations with focusing breaking waves have been made to examine the effect of wave-body interaction on horizontal wave impact on deck-box. The present CFD simulation results clearly show that the flows in front of column are strongly accelerated in vertical direction by blocking effect of column and pontoon, eventually producing strong run-up jets. The run-up jets in the present study are so strong that the direct impact of the incoming breaker on the wall does not occur, which leads to much smaller peak pressures, compared to those of centerline.

scholarly journals Wave Impact Pressures on Stepped Revetments

2018 ◽  
Vol 6 (4) ◽  
pp. 156 ◽  
Author(s):  
Nils Kerpen ◽  
Talia Schoonees ◽  
Torsten Schlurmann
Keyword(s):  
Probability Distribution ◽  
Vertical Axis ◽  
Step Height ◽  
Impact Loads ◽  
Wave Impact ◽  
Wave Flume ◽  
Horizontal Wave ◽  
Normal Probability Distribution ◽  
Log Normal ◽  
The Impact

The wave impacts on horizontal and vertical step fronts of stepped revetments is investigated by means of hydraulic model tests conducted with wave spectra in a wave flume. Wave impacts on revetments with relative step heights of 0.3 < Hm0/Sh < 3.5 and a constant slope of 1:2 are analyzed with respect to (1) the probability distribution of the impacts, (2) the time evolution of impacts including a classification of load cases, and (3) a special distribution of the position of the maximum impact. The validity of the approved log-normal probability distribution for the largest wave impacts is experimentally verified for stepped revetments. The wave impact properties for stepped revetments are compared with those of vertical seawalls, showing that their impact rising times are within the same range. The impact duration for stepped revetments is shorter and decreases with increasing step height. Maximum horizontal wave impact loads are about two times larger than the corresponding maximum vertical wave impact loads. Horizontal and vertical impact loads increase with a decreasing step height. Data are compared with findings from literature for stepped revetments and vertical walls. A prediction formula is provided to calculate the maximum horizontal wave impact at stepped revetments along its vertical axis.

Airgap and Wave in Deck Impact Statistics

2016 ◽  
Author(s):  
Øistein Hagen ◽  
Thomas B. Johannessen ◽  
Jørn Birknes-Berg
Keyword(s):  
Structural Reliability ◽  
Gap Analysis ◽  
Impact Load ◽  
Wave Theory ◽  
Limit States ◽  
Wave Impact ◽  
Weakly Nonlinear ◽  
Horizontal Wave ◽  
Wave Heights ◽  
Simple Limit

As offshore reservoirs are depleted, the seabed may subside. Bottom fixed installations which have previously had sufficient clearance between the deck and the sea surface may be in a situation where wave impact with the deck must be considered at relevant probability levels. Some statistical aspects associated with the calculation of a deck impact load with a prescribed probability of occurrence are the subject of the present paper. The Short Crest JIP addressed the distribution of the crest height in extreme sea states, the properties of the largest crests and the deck impact loading on a closed deck. It was concluded that the largest waves in the sea may be in the process of breaking and thus have properties which deviate significantly from estimates found from weakly nonlinear irregular or regular wave theory. The present paper addresses findings from the Short Crest JIP regarding • long-term analysis of wave heights and crest, including the effect of wave breaking • air gap analysis for jacket, TLP and semisubmersible using 2nd order time domain simulations over the platform area • statistics for horizontal wave-in-deck impacts for short crested sea versus for long crested sea • structural reliability analysis of jackets for some simple limit states that are governed by loads caused by impact of extreme crests

DEEP- WATER RESERVOIR APPRAISAL IN THE PHILIPPINES: AN INNOVATIVE EXTENDED TEST

1989 ◽  
Vol 29 (1) ◽  
pp. 11
Author(s):  
D. McGuinness ◽  
J. Branson
Keyword(s):  
History Matching ◽  
Water Reservoir ◽  
Weather Conditions ◽  
The Philippines ◽  
Drilling Rig ◽  
Bottom Hole ◽  
Acceptable Model ◽  
Bottom Hole Flowing Pressure ◽  
Economic Analyses ◽  
Geological Complexity

The extended test arrangement for the Galoc Field, offshore Philippines, consisted of a semi- submersible drilling rig having a conventional spread mooring to which was connected a storage tanker. The tanker was moored stern to the rig by a disconnectable hawser. At its bow, two anchor lines, also disconnectable, were laid in N/S quadrature symmetrically disposed about the NE/SW tanker orientation. The tanker was thus free to depart from the location, either to discharge its stored oil or to stand by/take cover in the event of heavy weather conditions exceeding the capacity to stay on location.At each lifting, a bottom- hole flowing pressure survey was conducted immediately prior to shut- in. When the well was shut in to disconnect the tanker, the pressure survey incorporated the pressure build- up and subsequently, after reconnection, the pressure drawdown transients. The data batches were collected on digital tapes for analysis.With only three wells in the structure proper, the geological complexity of the reservoir setting did not permit a definitive interpretation of reservoir behaviour during the extended test. However, the use of generic descriptions of submarine fan turbidite deposits, in com- bination with the results obtained from the three wells and history- matching attempts in reproducing the extended test behaviour, did result in a good level of confidence that we had derived an acceptable model of the Galoc Field. The forecast production profiles derived for the various development schemes were thus considered to be reliable enough for comparative economic analyses of the development options.

scholarly journals Desert Related Death

2021 ◽  
Vol 18 (21) ◽  
pp. 11272
Author(s):  
Mohammed Madadin ◽  
Rozanna Al-Abdulrahman ◽  
Shatha Alahmed ◽  
Rana Alabdulqader ◽  
Lama Alshehri ◽  
...  
Keyword(s):  
Cause Of Death ◽  
Forensic Medicine ◽  
Causes Of Death ◽  
Case Reports ◽  
Weather Conditions ◽  
Narrative Review ◽  
Safety Regulations ◽  
Common Causes ◽  
Environmental Causes ◽  
Death Causes

Introduction: Desert death is defined as any death that occurs in the desert and could be attributed to a list of causes including environmental, animal related, undetermined, and other causes. Death in the desert seems to be obscure and little discussed in the field of forensic medicine, despite its importance, and there is only limited literature available on this broad topic. This narrative review aims to identify the most common causes of desert death and its medicolegal implications. Desert death causes: Environmental causes of death could be a result of temperature and lightening-related causes. Moreover, a variety of animals found in deserts are considered to be threatening and fatal, in addition to other and undetermined causes. Medicolegal implications of desert death: Likely to arise from the difficulties faced in finding the cause of death are the identification of the victim and the postmortem injuries that occur. Conclusion: Desert death is a broad topic with great medicolegal significance. More information and case reports need to be added in the literature. Guidelines for people about the danger of going to deserts in specific weather conditions should be implemented. Safety regulations must be taken into account at all times.

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