Tanker Operations PDF

A double-hull tanker contains void space that can be used for segregated ballast Ullage measurements are taken from the top of the liquid to an above-deck datum usually at the top of the ullage hole A net barrel is equivalent to 42 gallons at 60*F Piping that routes cargo from the main to indiv...

A double-hull tanker contains void space that can be used for segregated ballast Ullage measurements are taken from the top of the liquid to an above-deck datum usually at the top of the ullage hole A net barrel is equivalent to 42 gallons at 60*F Piping that routes cargo from the main to individual tanks is known as a branch line Which characteristics are advantages of gate valves as compared? “Precise flow control and no resistance to the flow of cargo when opened LEL is the smallest percentage of vapor in the air that will allow for an ignitable mixture The valve typically found on the discharge side of a cargo pump on a tank vessel that is designed to permit flow in one direction will usually be a Check Valve The maximum amount of resistance to flow in a liquid is Viscosity The grounding of the Torrey Canyon led to the ratification of MARPOL 73/78 1 Metric ton = 2,204.4lbs Vessel cargo pipelines should be pressure tested annually A single fitting installed in a pipeline that either blanks it off or allows full flow of passage is a spectacle flange Manufacturers create the SDS Closed Gauging is a method of gauging that does not allow the atmosphere to exit the tank When the probe of an electric Gauging tape is in contact with oil, the horn will sound continuously Miscibility is the measure of the tendency of two liquids to form a uniform blend The lowest temperature at which a LIQUID will give off sufficient vapors to ignite and burn is Fire Point Jumperhoses may be used to crossover from one system to another Hydrostatic pressure is the force exerted by a fluid due to the force of gravity According to ARFA, an LR1 vessel has a deadweight tonnage of 80k-160k The threshold limit value for short-term exposure is the concentration of a substance to which workers can be exposed to for a short period of time Less Than 15 Minutes The Autoignition Temperature is a temperature at which no spark or flame is required to ignite a gas or vapor During cargo transfer operations, a static accumulation may arise in cargo due to the following except: A lightning storm in the vicinity of a vessel conducting cargo operations Vessels typically associated with pumprooms are crude oil tankers The fitting at the end of a cargo line that allows suction to be taken close to the bottom of a tank is a bell-mouth Explain the advantages and disadvantages of a double hull tanker: Double hull tankers significantly reduce the risk of pollution incidents and allow for easier cleaning of tanks  but corrode faster, crack easier, and are more expensive in terms of contraction and maintenance Explain the terms Purging and Gas-freeing: Purging introduces inert gas to an already inert tank to reduce the amount of hydrocarbons to less than 2% such that fresh air will not create a flammable atmosphere. Gas-freeing introduces fresh air into the tank; other vapors are expelled from the tank Describe what a crossover aboard an oil tanker is and why they might be needed: Crossovers are required to cross over between different cargo systems or segregations aboard tankers. This may be done via Jumperhoses or a Mix Master Explain P/V Valves and their typical location: P/V Valves protect tanks from over or under pressurization. These valves reset after operation and each tank has one, typically at the top Explain the basics of a metritape gauging system: A stainless steel core is covered in an insulator with a bare srtip exposed. Wire is wrapped around the core but does not touch it until it is squeezed. It has no moving parts and is not affected by steam or foam. Cargo hoses are pressure tested annually Inert Gas systems should be capable of delivering gas with less than 8% O2 Regulations require full propeller immersion When discharging oil, first consideration is getting the bow up When stripping, excessive air in the suction line may cause loss of suction Pipeline valves will not increase friction of liquid flowing to a pump and cause a loss of suction head Segregated ballast can be loaded mechanically What is required to prevent elctrostatic build up in tanks when using a crude oil washing system? The source tank for cleaning machines must have at least one metre decanted from it Petroleum cargo tanks should not be topped off in cold weather because a subsequent rise in temperature will cause cargo to overflow Reduction in number of pumps is not an advantage of deepwell pumps When tank cleaning with a portable machine, the weight of the machine is suspended by the supply hose which supports itself What is not a requirement for safe and effective use of crude oil washing systems? Use portable washing machines to reach areas obscured by structural members in tanks After dirty ballast is transferred, it should be allowed to settle prior to being discharged throught the oily water separator When cleaning a tank by butterworth process, you should pump out the slops in cargo tanks when the process has started  When cleaning tanks with portable machines, how is the machine grounded? The water supply hoses contain internal wires that act as conductors Functions aboard a tanker must be supervised by a designated PIC for the tanker/tank barge The most likely time for oil pollution to occur is when final topping off is occuring Power Packs supply high pressure hydraulic oil to operate hydraulic pumps Topping off occurs at the end of operations Mooring lines on working drums should have about 3-4 wraps Your vessel is taking on cargo oil when a small leak develops at the connection between the shore hoses and the manifold. You order pumping stopped. Before you resume, you should replace the gasket at the connection Centrifugal pumps are not self priming and decreasing speed will decrease discharge pressure Cargo pumps are generally located aft, near the centerline in a tank What may cause a centrifugal pump to cavitate? Practically/Theoretically? : Cavitation happenes when pressure in the suction line falls below the vapor pressure of the cargo. This may be caused by loss of prime or the speed of the pump Expalin the Inert Gas system from generation to delivery. Identify general requirements in systems capabilities as well: Generation begins in a boiler that creates exhaust. It travels to a scrubber that removes solids, corrosives, or excess water. The gas is also cooled as part of this process. Water is then removed via condensers and vortex separators.After the scrubber, it passess through a fresh air inlet by two fans that must be able to operate at 125% of all discharge capacity. There are systems in place like P/V valves and deck seals that prevent the back flow of gas. On discharge, oxygen must not be greater than 8%. Visual inspection should be performed how often pursuant to the VGP? What VGP mandates this? The VGP mandates daily inspections as per section 4.1.1 Describe how an eductor works: Educators are utilized in stripping and require drive fluid, typiclly from slops. They create low pressure on a suction line using the venturi effect.