SY/T 10035-2000 Specification for towing and positioning of drilling platforms
Some standard content:
ICS75 180 10
Registration No.: 6957—2000
Offshore Oil and Gas Industry Standard of the People's Republic of ChinaSY/T10035-2000
MODU Towing and Positioning Operation Rule2000-0410Promulgated
State Administration of Petroleum and Chemical Industry
2000-10-01Implementation
SY/T10035—2000
Policy Statement
1Scope
2Referenced Standards
3Definitions and Symbols
4Operation Conditions
Operation Plan
Structure and Stability
7System and Equipment||tt| |8 Towing operations
9 Positioning operations·
Appendix A (Standard Appendix) Basic requirements for the operation plan Appendix R (Suggestive Appendix)
Drilling platform towing and positioning operation procedures
References
Acknowledgments (Suggestive Appendix)
SY/T10035—2000
In the past decade, my country's offshore oil exploration and development business has developed rapidly and has become one of the industries with the most foreign cooperation. Considering the above reasons, this standard is not only compatible with the relevant specifications of China Classification Society (CCS) (including the relevant specifications of the former China Ship Inspection Bureau), but also adopts the Norwegian Classification Society (DNV) specification "RULES FOR LANNING AND EXECUTION OF FARINE OPERA-TIONS
—DNV1996.
The TOWING chapter in the DNV specification is the only standard on the operability of towing operations in the classification society specifications that we can find at present. Some applicable contents were adopted during the preparation. The applicability of various sea areas in my country was considered during the conversion of the clauses. This standard was issued on April 10, 2000 and implemented on October 1, 2000. Appendix A of this standard is the appendix of the standard.
Appendix B and Appendix C of this standard are the appendices of the reminder. This standard was proposed and managed by China National Offshore Oil Corporation. The drafting unit of this standard is China National Offshore Oil Southern Drilling Company. The main drafters of this standard are Mou Yongjian and Bie Shunwu. The chief examiners of this standard are Li Dingzhou and Kong Fuhua. SY/T1UUS5—2UUU
Policy Statement
Offshore oil and gas industry standard publications are only for general issues: For specific situations, please refer to national and local laws and regulations
Offshore oil and gas industry standard publications do not undertake to provide employers, manufacturers or suppliers with advance notice and training on health, safety and hazard prevention for their employees and other on-site operators, nor do they assume any responsibility under national and local regulations: The content of any offshore oil and gas industry standard publication cannot be interpreted by implication or other means as granting any right to manufacture, sell or use any method, equipment or product involving patent rights, nor does it assume any responsibility for any person who infringes on patent rights. Generally, offshore oil and gas industry standards are reviewed, revised, re-approved or revoked at least once a year: Sometimes, this review cycle can be extended to one year, but not more than two years at most. Therefore, the validity period of a publication shall not exceed one year from the date of publication, unless an extension of validity period is authorized. The status of the publication can be obtained from the Secretariat of the Offshore Oil and Gas Industry Standardization Technical Committee (telephone 010-84522162, the address is the Standardization Office of the Offshore Oil Production Research Center, Box 235, Beijing, 101149) or the Offshore Oil and Gas Industry Standardization Technical Committee (telephone 01064665361, the address is the Science and Technology Office of the Offshore Oil Corporation, No. 25, Dongjing Xin Building, Sanyuanqiao, Beijing, 100027).
The purpose of publishing offshore oil and gas industry standards is to promote proven and good engineering techniques and operating practices. It is not intended to eliminate the need to make correct judgments on when and where to apply these techniques and practices. The formulation and publication of offshore oil and gas industry standards are not intended to restrict anyone from adopting any other techniques and practices in any way. This standard can be used by anyone who is willing to adopt it. The Offshore Oil and Gas Industry Standardization Technical Committee and its authorized issuing units have made unremitting efforts to ensure the accuracy and reliability of the data contained therein. However, the Offshore Oil and Gas Industry Standardization Technical Committee and its authorized issuing units do not represent, guarantee or warrant the standards they publish, and hereby expressly state that they do not bear any obligations or responsibilities for losses or damages caused by the use of these standards, for the use of standards that may conflict with any national and local regulations, and for the consequences of infringement of any patent rights caused by the use of these standards.
1 Scope
Offshore Oil and Gas Industry Standard of the People's Republic of China Drilling Platform Towing and Positioning Operation Rule
MODU Towing and Positioning Operation RuleSY/T10035—2000
This standard specifies the basic requirements for the towing and positioning operations of offshore mobile drilling platforms. This standard applies to the towing and positioning operations of offshore mobile drilling platforms in my country for the exploration and development of offshore oil and gas resources. 2 Referenced standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest versions of the following standards. "Technical Rules for Mandatory Inspection of Seagoing Vessels"-
-1992 Ministry of Communications of the People's Republic of China
"Safety Rules for Mobile Offshore Platforms"
3 Definitions and Symbols
This standard adopts the following definitions.
-1992 Ministry of Communications of the People's Republic of China
3.1 Mobile Offshore Drilling Unit MODU (Mobile Offshore Drilling Unit) refers to an offshore mobile device that conducts drilling or other drilling-related operations for the purpose of exploring or exploiting marine oil and gas resources, and is referred to as a drilling platform or platform in this standard.
3.2 Operation conditions mainly include:
a) Towing - refers to the state or process in which the platform is towed by a tugboat as a towed object and transferred from a certain geographical location to another geographical location. Usually, a semi-submersible platform refers to the operation period from the last anchor leaving the bottom at the original well position (ship position) to the first anchor at the new well position (ship position); a self-elevating platform refers to the operation period when the hull is in a floating state: it refers to the state or process in which the platform relies on its own propulsion device to move from a certain geographical location to another geographical location;
c) Beginning of towing d) Towing/Transit to site refers to the operation of the platform starting to leave its original position after being towed; it refers to the operation process of the platform entering the well site and approaching and positioning to the predetermined position; Note: In the process of entering the well site, towing/shifting and in-position operations are intertwined. e) Positioning refers to the process of laying anchors or inserting piles at the predetermined position of the platform. For semi-submersible platforms, it refers to the process from the first anchor to the end of adjusting the pre-tension and calibrating the ship's position. For self-elevating platforms, it refers to the process from the pile foot entering the mud to the lifting of the ship to the ballast position;
) Operation limit (Operation limitation) A certain specified operation critical point of the platform. When the critical point is reached, the platform may be irreversibly damaged, that is, it cannot be restored to a safe and controlled state. 3.3 Type of towing refers to the form in which the tugboat is connected to the platform during the towing operation. It includes the following types: Approved by the State Administration of Petroleum and Chemical Industry on April 10, 2000, when the operating conditions or process exceed this critical point, it will be implemented on October 1, 2000. SY/T10035-2000
a) Single towing (Single tug towine) refers to the form in which a tugboat tows the platform,Usually the tugboat's main towline is connected to the platform's bridge cable. b) Series towing (Serestutawirg) refers to the form of towing the platform by connecting two tugboats bow and stern in a single connection, and the rear tugboat's main towline is connected to the platform's bridge cable;
c) Parallel towing (Paraleltugs1nwing) refers to the form of towing the platform side by side in which the main towlines of two or more tugboats are respectively connected to two parallel cables and/or other chains (cables) used as towlines; > Side towing (ieixelu Lnw) refers to the towing method in which the towline is tied to the left or right side of the platform; e) Bow and slr towing (Bow and slr mugslnwinz) refers to the towing method in which one tugboat tows the platform's lying part, and several tugboats tow the platform's left or right stern part.
34 Distance of lowing/trarisat is divided into:
a) Short distance towing/transit - refers to towing or transit operation with a distance of less than 100 nmile (including 1(X0) nmile)
b) Mid distance towing/transit - refers to towing or transit operation with a distance of 100 nmile ~ 300 nmile (including 300 nmile). In some standards, short and medium distance towing/transit operation is also called Freldmove:
Long distance towing - refers to towing operation with a distance of more than 3 rule, also called ocean towing in some standards.
35 Navigation area (Toing sca arra)
Can be divided into:
a) Open sea (0pr:n sra) refers to every area beyond 12n mile offshore: b) Offshore (Offshore) - refers to every area within 12 uile and 3(n mle offshore: c) Inshore - refers to the sea area within 12n mile (including 12nmile) offshore, also known as inland sea or sheltered sea area, 36 Workboat
Can be divided into:
a) Towing tug - refers to the general term for the main tug and the auxiliary tug: b) Main towing tug refers to the ship engaged in towing platform navigation during towing operations: c) Auxiliary tug tup refers to a ship that is engaged in personnel and cargo transportation, escort, clearing, and assisting platform lifting, throwing and positioning operations during navigation operations, and is required to be equipped with towing capabilities under specific conditions: d) Escort ship (Escortg) refers to a ship that is specialized in escort, clearing and has towing capabilities during towing operations, and is a type of auxiliary tugboat.
3 7 Towing group (Towing nperation gmup) refers to a temporary on-site command organization formed to implement towing/positioning operations, responsible for the implementation and safety of the operation: The towing leader is the towing group leader, and is called the towing master (TowMaster) in some standards. 38 Depth of towing Eire ralegory refers to the vertical distance from the lowest point of the suspension line of the towing cable in the water (the vertical point) to the point where the towing cable is tied, also known as the anchor angle. 39 Anchor mooning includes: a) Pretension: refers to the initial tension of the anchor chain when the horizontal displacement of the platform is zero; b) Soaking anchor: refers to the anchor staying on the seabed for a period of time before the anchor is tested for damage after being thrown, so that the anchor can be more effectively absorbed by the bottom. 4 Operating conditions 41 Requirements 41 The operating manual of the platform should clearly specify the types of operations allowed under different weather and weather conditions, and provide typical environmental condition models.
412 Operation time
SY/T 10035—2000
1. Wind speed and wave height not exceeding the design requirements of the platform: a meteorological forecast of stable weather and sea conditions that meet the operation requirements for at least three days after the start of voyage must be obtained. 42. Environmental conditions restrictions
421. When the wind force exceeds Beaufort 7 or the combined wave height exceeds four meters, the semi-submersible platform should not carry out operations such as anchoring, towing and positioning.
4.22. When the combined wave height exceeds one meter or the surge height exceeds - meters, the self-elevating platform should not carry out lifting operations. 423. In the presence of ice or when the water temperature is below 3000 degrees Celsius, the platform should not carry out lifting, mooring, towing and positioning operations. If such operations are carried out, a risk assessment should be carried out before the operation. 4 3 Weather forecast
431 Collection of meteorological data
4311 Regular weather forecasts should be received before and during towing operations: 4312 Weather forecast information should come from the National Meteorological Bureau or local meteorological stations. During unstable weather periods, weather forecast information should be sought or consulted with meteorological forecast agencies: 4313 Weather forecast procedures should take into account the characteristics and continuity of operations: 4.314 Atmospheric forecasts should be in written form: 432 Weather forecast content
432.1 Atmospheric situation and trend forecast A general description and weather forecast for the next 12h, 24h, 48h and 72h, including: a) wind speed and direction; h) significant wave/height, maximum wave/swell height, average/maximum periodic wave/swell height; c) weather, occupation, precipitation, ice, etc.; d) wind and tide: e) visibility: 9h steam temperature: 10h; air pressure: 12h. In addition to the above content, the weather forecast should also clearly give the definition of each forecast parameter, such as the time-specific period of wind speed (average or maximum), etc.
4.322 If the estimated operation time may exceed 72h, the weather outlook after 72h should also be provided: 433 Weekly forecast plan
4331 Before and during the operation, at least two weather forecasts should be received every day: 4332 In case of severe weather or unstable weather, more than one weather forecast should be received every day. 4 3 4 Risk assessment
Evaluate the operation risk according to the worst case weather forecast: The credibility of unstable weather forecast is low, so it is particularly important to do risk assessment before the operation: 5 Operation plan
511 Requirements
511 General principles
How to measure the average wind speed? The time for measuring the maximum wind speed is 2m, and the time for measuring the maximum wind speed is 38: The operation plan should be based on the meteorological and sea conditions in the unfavorable season and formulate response measures, including the strong winds and waves caused by the heat wave in winter and the early cold current in the sea area, wind marks and freezing in the sea area, etc.
SY/T10035—2000
5.1.1.1 The operation plan shall follow the principle of safety first (including the principle of failure protection) and be formulated in accordance with relevant standards and specifications and previous practical operation experience. For details, see Appendix Ac5.1.1.2 The operation limits shall be clearly stated in the towing operation plan. 5.1.1.3 The operation shall be carried out using proven applicable technologies and equipment. 5.1.2 Personnel and responsibilities
5.1.2.1 The towing leader shall be a person who has the captain's qualification and has platform work experience or has participated in at least five platform towing operations. In long-distance towing, the towing leader shall have the qualification of a Class A first-class ship captain. 5.1.2.2 The number of people on board during towing shall not exceed the rated number approved by the competent authority. 5.1.2.3 For platforms with self-propelled capabilities, their senior crew members shall have the corresponding certificates of competency. 5.1.2.4 A clear division of labor shall be made for operations related to towing. 5.1.3 Life material reserves
Life materials such as fuel, fresh water and food can be equipped according to the following standards a) When the towing time is within 10 days, the equipped quantity = daily consumption × 10 × 200%; b) When the towing time is 10 days to 20 days, the equipped quantity = daily consumption × planned days × 175% c) When the towing time exceeds 20 days, the equipped quantity = daily consumption × planned days × 150% 5.1.4 Loading quantity
The planned loading quantity shall meet the requirements of 6.1.1.1 of this standard, and additional work boats shall be added when necessary. 5.2 Towing method
5.2.1 Requirements
5.2.1.1 The main tugboat and auxiliary tugboat shall be equipped according to the needs of the operation, and the escort ship shall be equipped when necessary, see 7.4.1 and 7.4.2 of this standard. If the auxiliary tugboat is required to assist in the lifting, throwing and positioning operations, its horsepower should meet the corresponding operation requirements. 5.2.1.2 The appropriate towing method should be selected based on the towing distance, the platform's self-propulsion ability and towing resistance (mainly referring to the platform ship type), the weather and hydrological conditions in the navigation area, and the requirements of the platform operation manual. 5.2.2 Choice
5.2.2.1 Single towing should usually be given priority. 5.2.2.2 One of the following situations
may be considered for tandem towing or parallel towing! a) The horsepower of a single lean tugboat among the provided tugboats cannot meet the towing requirements b) It is expected to shorten the towing time
c) The platform has no propulsion system or the system cannot work properly. 5.2.2.3 Tandem towing or parallel towing should not be used in the following situations: a) The sea conditions in the navigation area are severe;
b) The navigation area requires escort ships to clear the way (such as fishing boat operation area). 5.2.2.4 When adopting the parallel towing form, the force of the platform's dragon whisker cable should be distributed symmetrically along the center line of the ship, and special attention should be paid to the coordination of the two tugboats:
5 When the platform enters and leaves the port, navigates in narrow waterways, or the self-elevating platform is in position at sea, the front and rear towing form should be used. 5.2.2.5
5.2.2.6 When entering the dock, the tethered towing method should be adopted. 5.2.2.7 When the self-propelled method is adopted for displacement, the requirements are the same as those for the single towing method. 5.3 Towing
5.3.1 Operation cycle
③ Failure protection means that the system can still remain in a stable and controlled state in case of failure. ① Usually, the horsepower of the escort ship equipped with a self-elevating platform should not be less than 2.795kw (3,800hp); the horsepower of the escort ship equipped with a semi-submersible platform should not be less than 4,780kw (6.500hp). Generally, when operating in the South China Sea, the lifting and throwing operation with an anchor chain length of more than 850m should be carried out by a workboat with a power of 5.884kw (8,000hp) or more. 4
SY/T10035—2000
5.3.1.1 The operation cycle should take into account the time delay caused by unpredictable accidents. 5.3.1.2 For operations of less than 12 hours, the start and end interfaces should be clearly specified. If the time of unexpected delay is not taken into account, the operation cycle can be calculated as twice the estimated operation time, but it should not be less than six hours at least. 5.3.2 Route
5.3.2.1 The route design should be based on the previous environmental condition statistics and/or weather forecast or experience. 5.3.2.2 The water depth of the route should keep the keel of the platform and tugboat at least five meters away from the seabed. 5.3.2.3 The width of the channel should generally be not less than three times the platform width.
5.3.2.4 If the tugboat and platform need to turn around when entering the site, the appropriate turning water area should be selected according to the weather and sea conditions and the towing length. 5.3.2.5 If the forecast weather and sea conditions may exceed the operational limit, a temporary sheltered anchorage or stake point should be set in the planned route. Environmental conditions (especially seabed conditions) information should be obtained when selecting a temporary sheltered anchorage or stake point. 5.3.3 Communication
5.3.3.1 A communication network plan should be formulated between the platform and the land, the tugboat and the land, and the platform and the tugboat, and the main and auxiliary communication tools and priority communication lines should be specified.
5.3.3.2 A description of the information flow planned to be implemented during the operation should be given. Important information should be transmitted on a dedicated line/channel; the VHF/UHF channels selected for use should avoid interference with internal and external communications. 5.3.4 Emergency plan
5.3.4.1 Safety measures and emergency plans during towing should be formulated according to the environmental conditions of the navigation area. 5.3.4.2 The platform shall be equipped with the following emergency equipment for temporary repair and plugging: a) 200kg quick-drying cement b) 200kg sand c) 10k concrete curing agent d) wood (including 40mm×300mm specifications): e) adhesive f) wooden wedge g) wooden plug h) angle steel i) plate steel i) steel cable t) portable submersible pump (can be kept on standby on the platform or tugboat). 5.4 Positioning 5.4.1 Requirements 5.4.1.1 If the environmental conditions at the well site are complex, it is advisable to select an appropriate speed to enable the platform to arrive during the day and to allow sufficient daytime operation time for the platform to complete the positioning operation.
5.4.1.2 For the requirements of the gyre waters, please refer to 5.3.2.4. 5.4.2 Determination of platform direction
5.4.2.1 The selection of platform direction shall be based on the dominant wind and current. For the platform with a white lift type, the crosswind and/or crosscurrent direction shall be used as the platform direction. Usually, the semi-submersible platform shall adopt the side wind and/or side head wind. 5.4.2.2 While giving priority to the platform environmental load and motion characteristics, the platform shall be protected to the maximum extent for safe operations such as drilling, berthing of three-purpose work boats, and helicopter take-off and landing.
5.4.3 Anchoring
5.4.3.1 For the platform that relies on the mooring system for positioning, the selected anchoring method shall be adapted to the load characteristics of the platform under specific environmental conditions. The mooring system shall be able to provide roughly the same restoring force (storm resistance) in all directions. 5.4.3.2 The length of the anchor chain (cable) shall not only meet the operational needs of the platform, but also take into account the operational limitations of the workboat and the influence of the seabed conditions. The calculation formula for the length of the anchor chain (cable) is: Where: L—the length of the anchor chain (cable).m; underwater length, m
5—the length of the vertical section of the anchor chain, m: SY/T 10035—2000
54.33 The length of the catenary should be calculated according to the safest working tension of the anchor chain (cable) and the water depth, using the core chain formula, so that the platform's deviation under extreme environmental conditions does not exceed the allowable range of the operation. The catenary length is
where:
The depth from the lower guide wheel to the seabed, m
S=V(d(2F/wd)
F—The maximum safe working tension of the chain (cable).kg;-The weight of each meter of anchor chain (cable) in seawater, up/m (The buoyancy coefficient of the anchor chain in water is 0.87. The buoyancy coefficient of the wire rope is 0.83~ 0.85). 543.4 The length of the horizontal bottom section should be selected according to the sea protection conditions to provide sufficient anchor chain grip, generally 100m~200m. The anchor key friction coefficient under various bottom conditions is shown in Table 1i. The friction coefficient of the anchor chain wall is used to calculate the total grip of the anchor chain. The dynamic friction coefficient is used to calculate the grip of the anchor chain during adjustment and sliding. 644 Insertion of peaches 5441 White lifting platform pile planting The seabed data of the lifting site should be obtained in advance. If necessary, core analysis should be carried out: 5442 Pile shoe platforms are usually suitable for hard soil, coral areas or other uneven seabeds. For soft beds, the insertion depth should be more than 18m-
5443 Sinking platforms are suitable for seabeds with small mud shear values (slope ≤ 1.5°), and should not be used in seabeds with coral areas and large gravels. 6 Structure and stability
61 Stability requirements
611 Stability and reserve buoyancy
6111 During towing, it should be ensured that the tugboat and the towing vessel have sufficient stability and reserve buoyancy: far During towing, it should be confirmed that the tugboat has sufficient stability under extreme environmental load conditions. 6112 The intact stability and damage stability should comply with the requirements of the corresponding ship classification rules, and supporting documents should be provided. 6113 The calculation of damage stability should take into account the operation procedures, environmental loads and dynamic response, continuous operation time and the consequences of possible damage.
61.14 Pay attention to the following possible reasons for water selection: 6
a) Impact loads and falling objects caused by the workboat: h) System failure;
() Misoperation:
d) Climate deterioration:
SY/T 10035—2000
6:15 The stability values do not include the temporary righting effect of components that are occasionally immersed in water (such as pipes hanging on the edge of the ship). 6116 The drainage facilities should be set up to drain the water level to an acceptable level. Otherwise, they should be measured and the influence of H should be considered in the calculation of stability.
612 Temporary closing facilities
6-21 Temporary closing facilities (such as hatch covers, flanges, exits, etc.) are susceptible to crushing or dynamic impact. They should be designed to be suitable for similar actions/loads and verified, and their reliability should also be confirmed: 6122 All manholes between buoyancy compartments should be kept closed during operations. 6123 Tank blue water. The draft and the parameters such as heel and drift should be regularly observed and recorded during the disturbance. 613 Stability calculation
6 131 When calculating the stability and buoyancy of the vessel, the variable factors in the vessel should be taken into account, including the weight of the variable load, the position of the center of gravity, the density of the liquid contained and the density of seawater.
6132 The number of free surface tanks should be minimized. If there are free surface tanks,61 4 Watertight integrity
6141 The number of openings in watertight bulkheads and center plates should be kept to a minimum. 6142 All access points, pipelines, ventilation and cables that penetrate watertight decks, external walls and bulkheads should be kept watertight and intact. 62 Structural strength
621 Overall strength
6211 For a unit that has been classified, the total deadweight of the unit should be within the permissible range according to the maximum deadweight recommended by the classification society (calculated based on the allowable shear and bending).
62 12 For a unit that has not been classified, the overall strength of the unit under towing should be calculated according to the original design standard of the unit, and supporting documents should be provided. 622 Upper strength
6221 The local strength of the unit should be verified. The actual condition of the unit, such as corrosion, damage, modification, etc., should be taken into account during the calculation. 6222 If the permissible load on the deck is indicated by a "load diagram", the limit load, load position and number of loads acting simultaneously are to be clearly indicated. In addition, it is to be stated whether the specified load includes dynamic load and design/load factor. The adopted load and material factor are to be mentioned here.
6223 The load-bearing structure of heavy cargo exceeding 101 placed adjacent to the deck is to be strength-verified. 7 Systems and Equipment
71 General
711 All systems and equipment of tugboats and platforms related to towing operations are to be inspected before towing to confirm that they comply with the design standards, certificate validity period and other general conditions, are in good condition and are suitable for the planned operations. 712 The operating manual of the tugboat and platform is to specify the following contents : a) Design standards:
b) Operational limits:
Detailed description of the systems or equipment used for towing. 7.13 The platform and tugboat shall comply with the requirements of Chapter 12 Life-saving Equipment, Chapter 13 Radio Communication Equipment, Chapter 14 Navigation Equipment and Chapter 15 Signal Equipment of the "Technical Rules for the Mandatory Inspection of Seagoing Vessels" (1992), as well as Chapter 8 Life-saving Equipment and Chapter 10 Navigation Equipment of the "Safety Rules for Offshore Mobile Platforms (1992)". The towing team members shall be familiar with the relevant contents. 7
7.2 Towing power facilities
7.2.1 Requirements
SY/T10035-2000
7.2.1.1 The towing power facilities shall be configured in accordance with the requirements of the classification society in order to effectively control the towed platform. 7.2.1.2 When configuring or using the following accessories, the effects of towing meteorological conditions on structural strength and operational requirements are to be considered: a) Towing eye plate (tow hook) of the towed platform; b) Chain guide (cable) hole of the towed platform; c) Arrangement of towing cables; d) Fiber bridge cables that may be used; e) Bridge (steel) cables: f) Dragon whisker chain (cable)/single chain; g) Triangular eye plate; h) Shackle; i) Towing electric ring: i) Towing cable segment or clevis; k) Towing cable recovery device.
7.2.2 Main towline
7.2.2.1 The minimum breaking strength (Minimum Break Lnad or MBL) of the main towline shall be selected according to the following formula: When BP ≤ 981 kN (100 t))
MBL? Towline ≥ 3 BP
MBL main towing cable ≥ 2BP (and ≥ 2
when BP>981kN(100)
7.2.2.2 The length of the main towing cable is determined according to the power of the tugboat, see Table 20 Table 2
943/kN/300)
Required minimum length of main towing cable
Tugboat power kw/Hp
≥14700/19992
≥7350/9996
≥2205/2,999bzxZ.net
7.2.3 Triangular cable
Minimum length of main towing cable m
7.2.3.1 The triangular cable consists of a dragon whisker cable (chain), a bridge cable and connecting parts, and is used to connect the main towing cable and the platform. 7.2.3.2 The triangular cable shall be configured according to the following requirements a) The length of the dragon beard cable (chain) shall be such that the two dragon beard cables (chains) form an angle of ≤60° b) In order to prevent wear, a section of chain shall be installed at the friction part where the dragon beard cable (chain) connects to the platform towing eye plate or towing fixed hook, and the length of the part extending from the ship's navigation fairlead hole to the connecting shackle shall be no less than meters:
c) In order to facilitate the towing and untowing operations, a 15m~60m bridge cable can be used to connect the main towing cable and the dragon beard cable (chain). For platforms other than China Classification Society (CCS), in addition to meeting the requirements of 5.1, they shall also meet the corresponding specifications of their classification society. 6DNV specifications for main towing cable MBL requirements:
MBL=4BP
MBL=0.8BP+16/BP
MBL=2.2BP
252 The triangular cable should be configured according to the following requirements a) The length of the dragon beard cable (chain) should make the two dragon beard cables (chains) form an angle of ≤60° b) In order to prevent wear, a section of chain should be installed at the friction part where the dragon beard cable (chain) connects to the platform towing eye plate or towing fixed hook, and the length of the part extending from the ship's navigation fairlead hole to the connecting shackle should be no less than meters:
c) In order to facilitate the towing and untowing operations, a 15m~60m bridge cable can be used to connect the main towing cable and the dragon beard cable (chain). For non-China Classification System (CCS) platforms, in addition to meeting the requirements of 5.1, they should also meet the corresponding specifications of their classification society. 6 DNV specifications for main towing cable MBL requirements:
MBL=4BP
MBL=0.8BP+16/BP
MBL=2.2BP
252 The triangular cable should be configured according to the following requirements a) The length of the dragon beard cable (chain) should make the two dragon beard cables (chains) form an angle of ≤60° b) In order to prevent wear, a section of chain should be installed at the friction part where the dragon beard cable (chain) connects to the platform towing eye plate or towing fixed hook, and the length of the part extending from the ship's navigation fairlead hole to the connecting shackle should be no less than meters:
c) In order to facilitate the towing and untowing operations, a 15m~60m bridge cable can be used to connect the main towing cable and the dragon beard cable (chain). For non-China Classification System (CCS) platforms, in addition to meeting the requirements of 5.1, they should also meet the corresponding specifications of their classification society. 6 DNV specifications for main towing cable MBL requirements:
MBL=4BP
MBL=0.8BP+16/BP
MBL=2.2BP
25
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