On DP vessel classification.pdf
- 1. On the DP1 Seaworker’s Class Reinstatement Dr. Danilo A. Navarro G. DP Systems commissioning specialist navdanilo@gmail.com
- 2. STEP 1: Determining vessel class compatibility from the equipment actually installed DYNAMIC POSITIONING SYSTEM ARCHITECTURE OF DP1 SEAWORKER VESSEL
- 3. Is the DP1 Seaworker a Class 1 Vessel? According to IMO MSC Circ. 645 (1994) and IMO MSC 1./Circ. 1580 (2017): YES, The DP1 Seaworker is a Class 1 DP Vessel. In light of above, is mandatory check thoroughly particular rules of the classification society to be choice by ship owner for the DP1 Seaworker Class reinstatement. However, according to ABS Guide for Dynamic Positioning System(July,2014), The DP1 Seaworker must have 2 wind sensor and 2 gyrocompass to meet Class 1 DP vessel classification requirements. The DP1 Seaworker also accomplishes particular rules of prestigious classification societies(Germanishe Lloyd, Bureau Veritas and Polish Register of Shipping among others) for Class 1 DP vessel classification.
- 4. What type of application may be the DP1 Seaworker used for? As stablished IMO MSC Circ.645, the equipment class of the vessel required for a particular operation should be agreed between the company and the customer based on a risk analysis of the consequence of a loss of position and/or heading. Otherwise, the Administration or Coastal State may decide the equipment class for the particular operation. There are equipment and redundancy conditions that would allow the DP1 Seaworker to be used in some class 2 application. However, IMCA M 103 shall be check thoroughly. However, according to IMCA M 103 (Dicember,2007), The DP1 Seaworker would be qualified as PIPELAY or CABLELAY VESSEL (if it is expected to work NOT close to offshore installations), as ROV SUPPORT VESSEL, OR as OCEANOGRAPHICS and SURVEY VESSEL.
- 5. May be the DP1 Seaworker upgrade to Class 2? Due mainly to redundancy conditions related to current equipment hardware , it is hard to achieve the DP1 Seaworker upgrade to class 2. Here are some TIPs. 1) Power system: Among others, POWER DISTRIBUTION SYSTEM must be redundant, and the system of DP1 Seaworker is not. Also, there must be a POWER MANAGEMENT SYSTEM, and there is not. 2) Thruster: thruster arrangement must be redundant and this may be costly prohibitive. 3) Control System: There must be 2 redundant control computer. Although already this hardware is on the DP1 Seaworker, it shall be verify and if necessary reprogram all the redundancy functions. This work rely on system’s manufacturer. 4) Sensors: Control computers of the DP1 Seaworker’s DP system are instrumented to manage up to 7 serial or NMEA sensors. But may be necessary to verify if software version can support them. Otherwise will be necessary system’s manufacturer intervention. 5) Consequence analyzer: the DP1 Seaworker’s DP system software possess it. 6) Failure Mode and Effect Analysis - FMEA: All failure modes and their effects should be considered in a formal FMEA study
- 6. Next step: to meet requisites for class 1 “the start point” to the DP1 Seaworker’s Class Reinstatement for the Coastal Authorities and General Customers, is to get the Class Certificate from a Classification Society 1) Posses and maintain an appropriate DP class issued by a Classification Society 2) The FMEA(Failure Mode and Effect Analysis ) of the DP System 3) Annual DP trials 4) DP Capability Plots 5) DP Footprint Plots Owner of DP vessel should be able to demonstrate to customer and authorities that their vessel comply with relevant IMO guidelines and classification societies rules. Aim for this, ship owner shall possess the following certificates.
- 7. The following pages gives a support to the facts presented here
- 8. On Vessels with Dynamic Positioning Systems Maritime Safety Committee. MSC Circ. 645. Guidelines for Vessel with Dynamic Positioning Systems July, 1994. Maritime Safety Committee. MSC 1./ Circ. 1580. Guidelines for Vessel and Units with Dynamic Positioning Systems June, 2017. IMO MSC Circ. 645 (1994) and IMO MSC 1./Circ. 1580 (2017) recommend design CRITERIA, necessary EQUIPMENT, operating REQUERIMENTS and a TEST & DOCUMENTATION system for dynamic positioning systems to reduce the risk to personnel, the vessel, other vessel or structures, subsea installations and the environment, while performing operations under dynamic positioning control.
- 9. DP Vessel Classification IMO MSC Circ. 645 (1994) and IMO MSC 1./Circ. 1580 (2017) are the principal internationally accepted references on which are based the DP rules and guidelines. These publication have become accepted as a world industry standard for vessel classification. About classification, IMO guidelines introduce the concept of the single point failure and redundant operations which allow for the continuance of position and heading ability after any single point failure. The necessary redundancy level for the components and systems are determined by the consequence of the loss of vessel position and/or heading. IMO MSC.1/Circ. 1580 has categorized DP Systems into 3 Equipment Classes based on redundancy and protection.
- 10. IMO Classes of DP Systems Class 1(Redundancy is not mandatory) A loss of position and/or heading may occur in the event of a single fault. Class 2(Redundancy is required for) A loss of position and/or heading will not occur in the event of a single fault in any active(generators, thrusters, switchboards, etc.) or static component(cables, pipes, manual valves, etc.) Class 3(Redundancy is required for) A loss of position and/or heading will not occur in the event of a single fault in any active or static component; or in all components in any one watertight compartment, from fire or flooding; or in all components in any one fire sub-division, from fire or flooding.
- 11. DP Vessel and Classification Societies The main classification societies have used the IMO principles of equipment and redundancy requirements as the basis of their on DP rules. Classification society rules differ and evolve and none is direct copy of IMO MSC Circ. 645 and/or IMO MSC 1./Circ. 1580. Rules for Classification and Construction-Ship Technology Dynamic Positioning System Requirements for Vessels and Units with Dynamic Positioning (DP) Systems Rules and Regulations for the Classification of Ships Dynamic Positioning System
- 12. DP class equivalent notation Note that some one of the classifier societies don’t have DP – 0 class.
- 13. Class Redundancy Requirements The need for redundancy will be indicated by a variety of means, but the concept have become accepted as a world industry standard is the “single point of failure” introduced by IMO: Redundant operation allows for the continuance of position and heading ability after any single point failure. Class 2 DP systems General Arrangement According to IMO MSC Circ. 645, vessels of equipment Class 1 will not be fully redundant in every area, but Vessels of equipment Class 2 have full redundancy in equipment and systems.
- 14. Class Redundancy Requirements According to IMO MSC Circ. 645, Class 3-designated vessels are capable of maintaining position and heading after the loss of all components in any watertight compartment or fire subdivision. In Class 3 a single-point failure might be the loss of one complete compartment. Class 3 DP systems General Arrangement
- 16. ABS Class Redundancy Requirements
- 17. PRS Class Redundancy Requirements
- 19. Which Class have to be a DP Vessel? The equipment class of the vessel required for a particular operation should be agreed between the company and the customer based on a risk analysis of the consequence of a loss of position and/or heading. Otherwise, the Administration or Coastal State may decide the equipment class for the particular operation. The International Marine Contractors Association IMCA M 103 Guidelines for The Design & Operation of Dynamically Positioned Vessels February, 1999 IMCA M 103 (1999) is a good reference for DP vessels class determination because it is a practical amalgamation of currents regulations, operations procedures and good practice based on interpretation of IMO MSC Circ. 645 (1994) and based on DP Vessels operations current experiences.
- 20. Which Class have to be a DP Vessel? According to the vessels operations, IMCA M 103(1999) recommends vessels should keep the following classification. 1. DIVING SUPPORT VESSELS, FLOATING PRODUCTIONS UNITS, ACCOMMODATIONS VESSELS, CRANE VESSELS, DRILLING VESSELS(on the basis that hydrocarbons can be present) and PIPELAY VESSELS(if they are expected to work close to offshore installations) are expected to be at least DP equipment class 2. 2. SHUTTLE TANKERS are expected have redundancy for no know single failure mode should cause a position excursion which necessitates emergency release of the loading and/or mooring hawser if used. Redundancy have to reduce the effect of failure mode and have to improve safe working limits. 3. ROV SUPPORT VESSELS are expected have redundancy for no know single failure mode should cause a position loss that could result in contact with another vessel, mooring line or offshore structure. Redundancy have to reduce the effect of failure mode and have to improve safe working limits.