Controlling Hydrocarbon Emissions from Tank Vessel Loading (1987) / Chapter Skim
Currently Skimming:
2 Current Practices on Tank Vessels
2 Current Practices on Tank Vessels
Pages 33-57
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 33... ...
They are generally unmanned except during loading and unloading when a Coast Guard certificated "tankerman" is required to perform operations. Tankships range upward in size and complexity to the extremes of maritime sophistication, with multiplecargo capability, closed-loading facilities, segregated ballast tanks, and inert-gas cargo blanketing systems to prevent fires and explosions.
|
From page 34... ...
The largest 50 companies operate about three-fourths of the fleet. The 3,968 inland tank barges have a total capacity of 52 million barrels and an average individual capacity of 14,500 barrels.
|
From page 35... ...
Tank barges range in length from less than 100 to several hundred feet. The simplest type, for petroleum and other liquids not considered I be highly dangerous, is a box divided by a longitudinal centerline bulkhead and several transverse bulkheads.
|
From page 36... ...
This type of arrangement is allowed only in Type III barges and barges designed for petroleum products. Double-skin tank barges have void spaces around the cargo tank sides and bottom.
|
From page 37... ...
Pump rooms are not necessary when deepwell pumps are fitted. On barges certified to carry cargoes with an open-cup flashpoint of 80°F or less, cargo tanks are fitted at their tops with pressure/vacuum (PV)
|
From page 38... ...
Lila Lid' alga aY Y Y Z Z Z Z jut am c`'a A, ~ A.) O O O O Z Z Z Z · · ~ ~ ° ~ ~ all > J _ > ala ~ O LIJ aD a: ale ~ Z Ma I [C C, ~ O O allla ~ LI Cta By CL ~ a~ ~: ~ <: ~lla ~ O a ~I a~ I a ~ ~ a ~ c~ c~ ~ O:\ id: Q r LL a_a > LU Z ~ ~a m ~ ~V ~ Z O ~ \ ° ~ ~ 0 c ~UD (D \~\ :: .
|
From page 39... ...
There are occasional loadings of kerosene and natural gasoline. Manning Requirements for Loading and Unloading Cargo transfer operations involving unmanned barges are under the control of tankermen, certificated by the Coast Guard to handle certain liquid cargoes in bulk.
|
From page 40... ...
On arrival at the dock, the barge is again inspected by both the loading foreman and the designated barge inspector, who also discuss loading procedures. A Coast Guard publication entitled A Manual for the Safe Handling of Flammable and Combustible Liqu i ds and Hazardous Products (U.
|
From page 41... ...
are extending to more tankships the requirements for inert gas systems and closed loading, and for ballast tanks separate from cargo tanks (the latter under requirements for segregated ballast tanks and clean ballast tanks)
|
From page 42... ...
Most combination carriers carry only crude oil when in petroleum service. Among the types of combination carriers are ore/oil carriers, bulk/ oil carriers, and product/bulk/oil carriers.
|
From page 43... ...
Cargo Tank and Pipeline Arrangements Figure 2-4 is a simple drawing of a complete direct pipeline system on a nonsegregated ballast tankship with a pumproom forward of the engine room. Only the three main centrifugal pumps are shown.
|
From page 44... ...
When many natural segregations are required, deepwell cargo pumps are installed in the cargo tanks. Crude Carriers Very large crude carriers (VLCC)
|
From page 45... ...
Deepwell cargo pumps are used extensively on chemical carriers or tankships carrying a great diversity of refined products. Each pump is installed in the cargo tank.
|
From page 46... ...
A vent line is installed in each cargo compartment so that vapors displaced during loading are released into the atmosphere. Similarly, when discharging, air or inert gas can enter the tank to replace the liquid discharged.
|
From page 47... ...
Ballast is carried in SBTs, CBTs, or cargo tanks. Ballast water, if placed in dirty cargo tanks, mixes with traces of the previous cargo clinging to the tanks and is called dirty ballast.
|
From page 48... ...
- A in: u]
|
From page 49... ...
Ballast water pumped into cargo tanks displaces the cargo vapors through the vent lines into the atmosphere. Coast Guard regulations governing departure from any U.S.
|
From page 50... ...
mi ~ m~ c m ~!
|
From page 51... ...
- Lou J ' 1 ~ -I ~ - )
|
From page 52... ...
Older and smaller tankships under 20,000 dwt not equipped with IG or not fitted with remote-reading ullage devices monitor cargo levels by looking into the cargo tank through ullage ports on the tops of the tank hatches (the ullage ports are fitted with flame screens, which are removed to permit viewing cargo levels)
|
From page 53... ...
Coast Guard examination for deck officer (as a third mate) or engine officer (as third assistant engineer)
|
From page 54... ...
Generally it takes about 6 hours to discharge the ballast from the cargo tanks. If the tanker has some or all of its ballast in segregated ballast tanks the delay for deballasting is reduced or eliminated entirely.
|
From page 55... ...
In COW operations, one or more of the tanks is washed with the crude oil cargo during discharge to minimize the amount of oil clingage in the cargo tanks. Cargo tanks selected to receive ballast water are usually crude oil washed during discharge.
|
From page 56... ...
On most crude oil tankships, the next incoming cargo is loaded on top of the slop oil that has been separated from the water. Slop should be discharged ashore to slop oil or dirty ballast receiving facilities.
|
From page 57... ...
Crude oil washing is also practiced on crude tankers with segregated ballast because it tends to improve overall efficiency. If additional cleaning is necessary for clean ballast, the vessel goes to sea and cleans the tanks with water.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.