94 PETROLEUM TECHNOLOGY, ECONOMICS, AND POLITICS
steam-driven models. In addition there were other developments
such as (1) the introduction of welded rather than screwed-in couplings; (2) the use of high carbon steel to replace lap-welded pipe;
and (3) the replacement of diesel equipment by electrically powered pumps. At the present time, the pipeline used for petroleum
transportation may be up to 48 inches in diameter and may cover
many thousands of miles.
Pipelines may be used to transport different types of crude oil
(batch transportation). When the different batches must be kept
separated to prevent mixing, slugs of kerosene, water, or occasionally inflatable rubber balls are used to separate the batches.
However, there is also the possibility that the batches can be transported through the pipelines without such separators. The properties of each batch may be such that mixing, other than to form
a narrow interface, is prevented. It is frequently necessary to pass
cylindrical steel cleaners through the pipelines, between pumping
stations, to maintain the pipeline clear of deposits.
Tank trucks are used for both lock and intermediate hauling from manufacturing and distance hauling from manufacturing and terminal points to individual domestic, commercial, and
industrial consumers that maintain storage tanks on their premises. Because of costs, most bulk deliveries by truck fall within a
radius of 300 miles.
Seagoing tankers (Figure 3.6), on the other hand, can be sent to
any destination where a port can accommodate them and can be
shifted to different routes according to need.
The seagoing tanker fleets that are owned, or used, by the
world's oil companies are also responsible for the movement of
a considerable portion of the world's crude oil. In fact, seagoing tankers form one of the most characteristic features associated with the transportation of petroleum. Many of these ships
are of such a size that there are few ports that can handle them.
Instead these large ships (VLCCs, very large crude carriers, and
ULCCs, ultra large crude carriers) spend their time sailing the
seas between different points, filling up and off-loading without
ever entering port. Special loading jetties, artificial islands, or
large buoys moored far offshore have been developed to load or
off-load these tankers.
In general, the larger the tanker the lower its unit cost of transportation. As a result, the size of tankers during the 1960s and
steam-driven models. In addition there were other developments
such as (1) the introduction of welded rather than screwed-in couplings; (2) the use of high carbon steel to replace lap-welded pipe;
and (3) the replacement of diesel equipment by electrically powered pumps. At the present time, the pipeline used for petroleum
transportation may be up to 48 inches in diameter and may cover
many thousands of miles.
Pipelines may be used to transport different types of crude oil
(batch transportation). When the different batches must be kept
separated to prevent mixing, slugs of kerosene, water, or occasionally inflatable rubber balls are used to separate the batches.
However, there is also the possibility that the batches can be transported through the pipelines without such separators. The properties of each batch may be such that mixing, other than to form
a narrow interface, is prevented. It is frequently necessary to pass
cylindrical steel cleaners through the pipelines, between pumping
stations, to maintain the pipeline clear of deposits.
Tank trucks are used for both lock and intermediate hauling from manufacturing and distance hauling from manufacturing and terminal points to individual domestic, commercial, and
industrial consumers that maintain storage tanks on their premises. Because of costs, most bulk deliveries by truck fall within a
radius of 300 miles.
Seagoing tankers (Figure 3.6), on the other hand, can be sent to
any destination where a port can accommodate them and can be
shifted to different routes according to need.
The seagoing tanker fleets that are owned, or used, by the
world's oil companies are also responsible for the movement of
a considerable portion of the world's crude oil. In fact, seagoing tankers form one of the most characteristic features associated with the transportation of petroleum. Many of these ships
are of such a size that there are few ports that can handle them.
Instead these large ships (VLCCs, very large crude carriers, and
ULCCs, ultra large crude carriers) spend their time sailing the
seas between different points, filling up and off-loading without
ever entering port. Special loading jetties, artificial islands, or
large buoys moored far offshore have been developed to load or
off-load these tankers.
In general, the larger the tanker the lower its unit cost of transportation. As a result, the size of tankers during the 1960s and