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Cargo ops > Petroleum > Flashcards

Petroleum Flashcards

1
Q

What are the three main hazards of petroleum and how do they pose a risk to the ship?

A

Flammability (fires/explosions)
Density (gives off gasses heavier than air)
Toxicity ( harmful to humans)

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2
Q

What conditions are required for petroleum gasses to burn?

A

Petroleum gasses only burn when they are mixed with air in the right proportion. The gasses are flammable when the proportion of gasses to air is between the lower and upper flammable limits. ( usually around 1 and 10%)

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3
Q

What is the flashpoint?

A

When liquid petroleum products are heated the concentration of gas increases. The temperature at which the concentration reaches the lower flammable limit is the flashpoint.

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4
Q

What is a volatile liquid?

A

A liquid with a flashpoint of less than 60 degrees Celsius

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5
Q

What is a non-volatile liquid?

A

A liquid with a flashpoint of 60 degrees Celsius or above.

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6
Q

What is the LFL?

A

Lower flammable limit. Below this limit there is insufficient hydrocarbon gas in the mixture to support combustion. The mixture is lean.

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7
Q

What is the UFL?

A

Upper flammable limit. Above this limit the is insufficient oxygen in the mixture to support combustion. The mixture is too rich.

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8
Q

What is the flammable range?

A

The range of mixtures of hydrocarbon gas that will support combustion. Between the LFL and UFL.

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9
Q

What are some possible causes of explosion/combustion?

A
  • Direct heat
  • Mechanical sparks
  • Chemical energy
  • Electrical energy
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10
Q

What are some sources of direct heat on a ship?

A

Hot work
Smoking
Funnel sparks

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11
Q

What are some things on a ship that might cause mechanical sparks?

A

Dropped tools
Chipping
Badly secured anodes
Cigarette lighters

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12
Q

What are some sources of chemical energy on a ship?

A

Metallic smears
Spontaneous combustion
Auto ignition
Polyphoric iron sulphide - produced when H2S is present with rust.

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13
Q

What are some sources of electrical energy on a ship?

A

Electrical sparks
Electrical arching
Lightning
Static discharge

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14
Q

How can static charges be created on a ship?

A
  • The flow of liquids
  • The flow of fuels through fine filters
  • The movement of contaminants through a liquid (slop tanks)
  • Gas bubbles rising through a liquid
  • Static accumulator oils (insufficient conductivity to dissipate a charge)
  • The splashing of a liquid against a solid surface
  • Water droplets or oil being ejected from a nozzle during tank cleaning
  • Synthetic ropes rubbing on PVC gloves
  • Wet steam condensing
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15
Q

What are some objects that may need to be insulated to prevent static discharges?

A
  • Ship/shore couplings and flanges if more than one non-conductive pipe or hose in a string
  • Portable tank cleaning machines
  • Manual ullaging and sampling equipment
  • A metal object such as a sampling can, floating in a static accumulating liquid.
  • A loose metal object while it is falling in a tank.
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16
Q

What is a static accumulating liquid?

A

A liquid with a conductivity less that 50 pico siemens per metre

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17
Q

What is earthing?

A

A connection to the main structure of the ship

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18
Q

What is bonding?

A

Connecting two metal parts together to ensure electrical continuity.

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19
Q

What are some safety precautions that need to be taken aboard petroleum cargo vessels?

A
  • No smoking on deck
  • No hot work on deck
  • Use intrinsically safe equipment at all times
  • Limit the initial loading rate
  • Ensure there are no hot surfaces near cargo tanks
  • Anti-static additive
  • Ensure electrical continuity of hoses
  • Only use earthed and bonded equipment in cargo tanks.
  • Be careful of ullaging and sampling equipment
  • Ensure there are no loose conductive objects in cargo tanks
  • Avoid splash filling by using a filling line that terminates close to the bottom of the tank.
20
Q

What is toxicity?

A

Toxicity is a substances ability to harm humans. Toxic substances can cause damage through ingestion, inhalation, absorption and injection

21
Q

What is TLV?

A

Threshold Limit Value. The maximum concentration of cargo vapours in air which personnel can be exposed to without adverse effects. Measured in parts per million of volume of gas in air.

22
Q

What is TLV-TWA

A

Threshold limit value - time weighted average. The maximum concentration of cargo vapours in air that a person can be exposed to for a regular 8hr day/40hr week.

23
Q

What is TLV-STEL?

A

Threshold limit value - short term exposure limit. The max concentration of cargo vapours in air that personnel may be exposed to for 15 minutes. Max 4 times per day with an hour between each time.

24
Q

What is the TLV-C?

A

Threshold limit value - ceiling. The concentration of cargo vapours in air that must not be exceeded.

25
Q

What actions should be taken when approaching a loading or discharge port?

A
  • Check tank level gauges
  • Check tank level alarms
  • Check thermometers
  • Check remote system controls
  • Check high level alarms
  • Check tank overflow control alarms
  • Check safety of critical components of the cargo transfer system.
  • All hatches, lids + openings to cargo tanks which are not required to be open for a specific purpose should be closed securely
  • All drains should be closed and secured
  • All cargo and bunker lines not in use should be securely blanked and fully bolted at the manifold.
  • Any cargo pipeline systems not in use should be isolated
  • Ventilation system in pump room should be checked
  • Cargo deck lighting should be checked
26
Q

What checks should be carried out before cargo transfer operations?

A
  • A weather forecast should be obtained
  • Ensure ship and shore vapour systems are compatible
  • A cargo data sheet should be on board
  • If the cargo is liable to self reaction the inhibitor certificate should be on board.
  • The tanks to be loaded should be inspected by an independent surveyor and a certificate obtained if necessary
  • Tanks passed for loading should be secured with all cargo openings secured
  • When not in use all sea suctions connected to the ballast and cargo systems should be secured. Where required they may be sealed by shore authorities
27
Q

What is the order of events for a loading port?

A
  • Pre-load meeting
  • Survey and sampling
  • Line checking and manifold connection
  • Commence loading at agreed slow rate
  • Commence loading at agreed rate once checked
  • De- ballast in accordance with loading plan
  • Bulk loading and de-ballasting checks
  • Loading rate decreased and topping off commences
  • Final survey and sampling
28
Q

Who attends a pre-load meeting and what do they discuss?

A

The master , chief officer and terminal representative discuss:

  • Ship/shore safety checklist
  • Loading plan
  • Cargo distribution on arrival and departure
  • Quantities of cargo to be loaded
  • Ship/shore tanks to be loaded and discharged
  • Ship/shore lines to be used
  • Cargo transfer rate
  • Operating pressures and maximums
  • Temperatures
  • Venting system
  • Restrictions on loading
  • De-ballasting sequences, tank changeovers
  • Trim, draught, stability and stresses
  • Stopping times
  • Flow times
  • Emergency stop procedure
  • Communications
  • Other operations to be carried out during loading (stores, bunkering, repairs, hot work)
29
Q

Describe the process of survey and sampling and what is required to perform this safely.

A

Could be basic sampling or could involve a ‘chemist’ and a cargo surveyor depending on the type and grade of product to be loaded. Sometimes the chief officer is taken to the shore tanks and a sample drawn in their presence. Some terminals supply sampling equipment that is fitted at the vessels manifold. Sampling and survey requires:

  • Closed gauging and sampling equipment
  • Portable equipment
  • Safety precautions
  • Earthing/bonding of sampling device and gauges
  • Vapour locks
  • Flame arresters
  • Restricted gauging equipment
30
Q

Describe the process of line checking and manifold connection and state what is required for this to happen safely.

A
  • 1 ships officer to set up the lines ready for loading
  • Double check of the lines by another ships officer
  • Any overboard valves checked to ensure they’re closed and secured
  • Lines must be set up as per the loading plan
  • A responsible officer must be in charge of the operation
  • SOPEP equipment must be available
  • Fire gear laid out
  • The correct equipment must be used to ensure connection is adequate
  • Ensure correct lines are matched/connected to the right manifolds
  • There must be adequate communication between the ship and shore personnel
  • The international ship/shore connection must be in place
  • All scuppers must be plugged
  • Gaskets in good condition
  • Manifold valves checked for correct operation
  • Manifold valves on opposite side to loading secured
  • Manifold valves on opposite side to loading secured
  • Manifold valves should not be opened until shore confirms readiness
  • Manifold valves should be the last valves to be opened
  • Loading should start slowly so connection can be checked for leaks
  • When checks complete loading rates can be increased.
31
Q

Describe how loading is commenced safely.

A
  • The inert gas system is shut down and isolated.
  • Inert gas pressure in cargo tanks reduced to prevent overpressurisation
  • If ballast tanks are to be inerted during he operation the IG plant should only be made common with the tanks to be inerted to ensure no cargo vapours can enter the ballast system through the IG line.
  • All tank ports should be closed. Any gas displaced vented via high velocity vents, the mast riser, or direct to shore.
  • Terminal and shore checks must be completed
  • Initial loading rate slow
  • When cargo is confirmed to be going to the correct tanks and there are no leaks, loading rate can be increased.
  • Where de-ballasting is to shore tanks, the sequence and connections must be agreed with the terminal before commencing
  • The cargo plan must me followed
  • Ballast from cargo tanks must be replaced with inert gas
32
Q

What things should be regularly monitored during bulk loading operations?

A

There should be regular patrols of the deck and pump room, and regular checks over the side for pollution. Regular monitoring of:

  • Pumps
  • Ballast
  • Cargo levels
  • Pressures
  • Moorings
  • Weather conditions
  • Ship/shore communications
33
Q

What does the topping off process involve?

A
  • Ensure that sufficient personnel are available
  • Ensure that the terminal is advised
  • Either open the next tanks to reduce the loading rate or reduce the loading rate.
  • In the later stages of topping off the loading rate may be reduced further, sometimes carried out by gravity
  • On completion each tank must be checked and monitored for leaks
  • The number of valves that are required to be closed during topping off should be kept to a minimum.
  • Where possible, the segregation requirements of the cargo should be adhered to
  • Do not close all the valves against the flow
  • The time required for stopping pumps or shutting down the system should be known.
  • The quantity of oil in the pipeline should be known and allowed for.
  • Shore control valves should be closed before the ships manifold valves are closed.
  • On completion, the chief officer should check that the cargo system has been completely shut down, all tank openings are closed, and the p/v valves are set correctly.
34
Q

What should happen at the end of cargo operations?

A
  • Drain all lines
  • Shut down cargo system
  • Gauge and sample
  • Check P/V valves
  • Secure vessel for sea
35
Q

What are the four main pipeline systems?

A
  • Ring main
  • Direct line
  • Free flow
  • Cruciform/combined
36
Q

What are the advantages of the ring main pipeline system?

A
  • Versatility: Any cargo pump can discharge any tank

- Good segregation: Permits high degree of tank separation

37
Q

What are the disadvantages of the ring main pipeline system?

A
  • Expensive in construction and maintenance due to high no. of bends and joints required
  • Poor flow due to restrictions caused by bends
38
Q

What are the advantages of the direct line pipeline system?

A
  • Fast loading and discharging rates: there are fewer bends and joints ensuring a minimum loss of pressure during loading and allows good suction to the cargo pumps during discharge.
  • Relatively cheap construction
  • Line washing time reduced
39
Q

What are the disadvantages of the direct line pipeline system?

A
  • Little versatility when loading different grades

- Leaks can be difficult to control due to small number of valves required.

40
Q

What are the advantages of the free flow pipeline system?

A
  • Fast loading and discharging
  • Efficient tank draining
  • Easy operation
  • Low maintenance costs
  • Cheap to build
41
Q

What are the disadvantages of the free flow pipeline system?

A
  • High risk of contamination between tanks

- Vessel is limited to carrying a single grade

42
Q

What is crude oil washing?

A

When oil cargo is used to clean the tanks. When oil cargo is sprayed on the tanks walls and surfaces, the sediments sticking to the tanks are dissolved and can be pumped out as useful cargo.

43
Q

What are the advantages of crude oil washing?

A 
Increased cargo out-turn
Reduction in cost of cleaning prior to D/D
Less manual desludging
Environmentally friendly
Reduction in ballast tank cleaning
Less sea water to be discharged to refineries
Less corrosion in tanks
Reduction in dead freight
44
Q

What are the disadvantages of crude oil washing?

A 
Increase in port time
Cargo loss due to increased vapour generation
Increased workload for crew in port
Higher training costs for crew
Pollution potential
Higher capital cost for installation
Reduction in overall discharge rate
45
Q

Why could a COW system be shut down?

A
  • Inert gas plant failure
  • Failure of oxygen analysing equipment
  • Low inert gas pressure
  • High oxygen content of inert gas
  • Any pipeline leakage
  • Tank overflow
  • Pipeline joint blowout
  • Sounding of any alarm bells
  • Failure of tank gauging systems
  • Changing ullage in tanks not being discharged
  • Failure of communications
  • Difficulty in keeping the ship alongside
  • Bad weather
  • Any unsafe situation developing
  • Shore instructions/emergency

Cargo ops (2 decks)

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