Answer

Question One: An Inert Gas System

1. Outline design of an Inert Gas System suitable for a VLCC

Tankers transporting oil contains oil of varied gradings and characteristic. This variation in internal chemical composition has the potential to explode and result in losses. The explosion process is normally caused by mixing of air with flammable gases contained in the tanker (Siswantoro et al. 2020). In order to minimize property damage and life loss during transportation of oil, Inert Gas System (IGS) is fitted to the vessel to manage gases produced during the voyage. Very Large Cruise Carrier (VLCC) is fitted with IGS which is a complex system for oil transporting tankers in enhancing safety and reducing all forms of risk and losses that may be incurred. Inert gases on the other hand are collection of unreactive gases with oxygen composition which is below 8% and reduces combustion of flammable gases produced by oil. Diagram 1.1 below shows an outline of IGS.

Diagram 1.1: Inert Gas System outline (Source: Anish 2021)

1. Key Components of an Inert Gas System and the Function of Each System

The IGS has a number of components that helps to ensure it meets its functions (Audi et al., 2021). The following are list of the components and functions performed.

• The exhaust gases inlet: This section allows movement of inert gases to the engine because of the presence of flue gases.
• Inert gases separation valve: The component controls intake of inert gases when the system is operational or non-operational.
• Souring Tower: Flue gases ascend the tower as they are cooled purified and moisturized to produce colorless smoke.
• Demister: Functions as moisture absorbent of flue gases because of polypropene used.
• Gas Fan: Turbine propelled blower propel gas in the system as the electric fun is used for adding gases to the system.
• Pressure Regulator: Atmosphere and oil composition results in pressure variations. Pressure regulator reduces the ration and enhances cooling.
• Deck Seal: Maintains a single directional flow of gases from fans to the cargo. They are moisturized to enhance gas movement.
• Mechanical Valve: Performs the same function as deck seal.
• Isolating Valve: Separates the engine room components from the deck components using the valve.
• Pressure Vacuum Breaker: Control excess or low pressure of cargo tanks. It is equipped with flame trap to protect explosion during loading or discharge.
• Cargo Tanks Isolating valves: Different cargo holes are equipped with separating valves. Flow of Inert gases in the holds is regulated by the valves.
• Mast Riser: functions as pressure controller of inert gases during loading and is left open for pressurization control.
• Security Alarm Unit: This unit is equipped with different safety inputs for tank and machinery safety.

1. Question 1. It is intended to carry out Crude Oil Washing during discharge of the cargo. Discuss the precautions and hazards associated with Crude Oil Washing

Crude Oil Washing (COW) is a process of washing oil tankers on voyage using oil rather than water. However, COW practices present a number of hazards that requires safe considerations to ensure safe execution of activities. The first precaution is associated with the supervision process of COW (Milković et al., 2021). According to outlined precautions, the Chief Officer is mandated to prepare COW washing plan before arrival of the vessel. The second precaution is on discharge techniques stating that the vessel must be inspected to ensure proper drainage trim at the beginning of discharge. The discharge process should not take place without inert gas system. The third consideration is on prior request to the port to ensure conditions for discharge are attained and in line with the discharge activities

Refence to COW manual during the discharge is another essential precaution carried out during washing process. The discharge and washing must be carried out using directives from Operations and Equipment manual. Advance notice prior to docking is another requirement by the vessel master to seek permission at the port. Additional consultations should be carried out before commencing the washing process. Other precautions for COW include observation of safety measures for COW operations, pressure test prior to docking and ensuring that tanks atmosphere is washed using crude oil. 

Question Three

1. Chemical Tankers for the Carriage of Noxious Liquid Substance (NLS) in Bulk

Ship loaded with noxious substances in bulk have the potential to cause havoc in the environment. Controlling such havoc is regulated by different certificates of operation. The resolution 18 (22) according to Procedure and Arrangement manual provides that a ship loaded with noxious liquid substance in bulk should have international pollution prevention certificate (“Noxious Substances – Maritimeknowhow”, 2021). This certificate is issued with reference to regulation 10 of the MARPOL 73/78 seeking to regulate pollution caused by noxious liquid substance. Additionally, certificate of Fitness for the Carriage of Dangerous Chemicals is given with considerations to the Bulk Chemical Code for all chemical tankers.

According to the certificate issued, the legislation is under MARPOL 73/78 and is a requirement for all ships carrying Noxious Liquid Substance (NLS) in bulk. The issued certificate is expected to last five year from the date of issuance and is subject to termination in events of content changes and unauthorized ownership transfer to other vessels as stated in Regulation 12.  This certificate has no extension and is issued following initial surveys prior to release of the vessel to the service. Request for this certificate is usually by the vessel owner followed by administrative adherence from authorized organizations. Additional inspections are carried out by authorized organization to evaluate operations adherence to the certificate.

Resolution 18 (22) is a standard for all procedures and arrangements offload all NSL as outlined in Procedure and Arrangement Manual (PA Manual). The manual offers guidelines for NSL or water found in the substances from the washing process. The NSL            applies four classification of liquid substances carried on board. Classes contained in PA Manual are A, B, C, and D with reference to Annex 2, Regulation 5 of MARPOL 73/78 (“Noxious Substances – Maritimeknowhow”, 2021). Standards for pumping, loading and pipping system of NLS vessels are offered in the manual as a measure of control. Regardless of the vessel used, the manual states that Procedures for Arrangement shall be provided by port administration.

Compression of NLS Certificates and PA Manual

Both NSL certificate and PA Manual adherence is offered from a given authority. Taking for instance, NSL Certificate is issue and administered by administration or authorizing body and the same practice is applied in PA Manual which is administered by authority. Secondly, there is arising similarity in the two documents on their major goals to reduce loss and pollution at the sea possibly arising from carriage of NLS that can lead to havoc. An outstanding example of this is commitment to control loading and discharge of liquid substances in the tankers as well as washing requirements outlined in each case. 

Contrast in NSL Certificate and PA Manual

The NSL Certificate has validity period and is subject to expiry and renewal according to the issuing authority requirements. The certificate has a five-year validity upon which fresh application by vessel owner is required. Contrary to the Certificate, PA Manual is a standard of operation procedures outlined tor each vessel according cargo requirements and port specifications and available handling equipment. The manual therefore lacks expiry dates and is continuously used in ensuring safety of bulk NSL tankers and reduction of pollution. The next difference observed from manual and certificate is that certificate is issued upon a vessel attaining specification while the manual, being standard operating procedures, offers guidelines for pumping, loading and washing of NLS vessels and tanker (Seo et al., 2020). The manual can thus be concluding as a guide of activities carried out by NSL ship as the certificate offers regulatory measures used to observe adherence to MARPOL 73/78 and the Annex.

1. Five typical items with regards to (CoF, P&A, type of cargo, compatibility, segmentation

Loading vessels with bulk NLS is extremely hazardous and therefore requires prior planning to avoid possible losses that may be incurred. The prior planning required evaluation of cargo volume, characteristic and other composition details to determine best handling methods (Lihong et al., 2021). At the begging of loading, precautions should be taken on the volume and class of liquid chemical cargo being loaded and the loading rate permitted at the port. Other precautions include verification to ensure that all ship personnel are ready for the voyage and a completed shore checklist for all requirements. Additional requirements are precautions for managing vapor pressure cargo, clearance by shore piping inspection and use of compressed gas in the vessel.

Bulk liquid chemical cargo has specific requirement according to the Certificate of Fitness (CoF) directives. Prior to loading of the tanker, CoF outlines that the correct chemical naming should be provided together with weight and contamination extent in parts per million (ppm). Further requirements include gravity declaration, temperature details and compatibility of reactive chemicals in adjacent tankers. The certificate seeks to establish tank coating characteristic and corrosive impacts that are likely to damage the ship and result in serous environmental losses. Additional information inspected is electrostatic generation report from material used and fire and explosive data in an event of accidents. Complete report on a ship will lead to issuance of International Certificate of Fitness for bulk liquid chemical cargo.

Transportation of different bulk liquid chemical substance requires appropriate planning and arrangements prior to commencement of the voyage. The firs planning executed is the cargo loading plan that takes into considerations six aspects. The first aspect deals with tank capacity and provisions for expansion while the second aspect evaluates the tank coating material for safety of carriage. Other considerations are given to adjacent cargo impact, planning on temperature control measures and tank cleanliness evaluation. Other considers are on loading and discharge plan used in the vessel together with cargo stowage plan for parcel distribution.

 Some ships prepare to transport different types of liquid chemical substances that can easily react with each other. In such case, segmentation is applied while taking special considerations to their compatibility. Since there are unseen precautions of possible reaction and explosion from the process, there is need to have a proper planning in segmentation and compatibility properties of the tanker before commencing the journey.

To begin with, evaluation is given to compatibility properties with water where colling is required but the chemical is reactive to water. Planning in this process is creation of segmentation that reduces water contact to the liquid chemical on voyage. The next consideration is on compatibility to coating materials used in tankers. Prior to lading of liquid chemical substance, precautions should be observed to check coating chemical substance suitability and temperature limits that can be accommodate in the tanker. Last precaution is on compatibility of edible oils as the liquid chemical substance. Before loading of the tanker, toxic chemicals should be labelled with BCH and IBC coding standards and their segmentations should never be adjacent edible oils as provided in Federation of Oils, Seed and Fats Association (FOSFA).

Question 4. How to Minimize Unfortunate Event of a spill Occurring During Loading Light Crude

Unfortunate oil spill is the accidental spillage that takes place when loading of a light crude oil tanker fails. In an event of accidental oil spill, consequences are faced to both human and the environment. Among notable consequences of oil spillage is death of sea animals and birds. In order to address consequences faced when there is an oil spillage MARPOL 73/78 under considerations to Annex 2 provides guidelines for reporting and control measures to be undertaken according to the specifications of vessel in question. On the other hand, this section and chapter provides reporting procedures for unintentional oil spillage encountered during loading.

How Unfortunate Event of oil Spill Occur when Loading Light Crude Oil

Oil spill events occurs as a result of accidents faced during discharge or loading of crude oil tankers. The major causes of such spills are not normally known and can only be blamed on negligence which eventually translates to a serious havoc (Sing et al., 2020). Release of oil whether through leakages or unintentional loading failure can lead to release of large volumes of oil on the water surface. Spilled oil on the water surface has the potential to spread to other regions that are far from the actual point of the incident. Addressing such issues, therefore, requires application of specified measures to reduce damage caused to the sea and possible explosions.

Steps to Minimize Impacts of Oil Spillage

When oil spills occur, chances are not taken to minimize the spread of oil in other areas. One step to ensure release incident is reduced is by vessel servicing activities carried out prior to loading. Activities undertaken includes evaluation of the status of the tanker prior to loading to ensure there are no leakages. The next step is by reducing possibilities of overflow, shutting bilge pump while loading and opening after loading and use of absorbent and staying closer to the stash. When the spill has already taken place, prompt cleaning needs to be conducted to ensure the spread is minimized. A swift reporting action also need to be taken to alert the authorities in case of any emergency response need to reduce the extent of the damage.

Reporting Procedure for Oil Spillage

Reporting of unfortunate oil spillage is a mandatory step required by the local authority to determine response measures to be used. In reporting a spill, the master begins by notifying the relevant authority based in the central reporting center. The reporting center officer will then require disclosure of information pertaining master’s name, location and name of the carrier vessel. Additional details will include location where the spill has taken place and cause of the incident together with type of material released and extent of the spread. The authority shall then send surveyors to analyze the spill and provide a detailed report on the extent and risk level that is likely to be faced when the spill is left uncontrolled. The reporting process will contain specification on the immediate medium affected by the spill and number of casualties if any. The report needs to state in there have been evacuation and other related details that may be used to offer emergency services.