Tanker

When process tanks, road tankers, or rail tank cars are filled, material in the vapor space is forced out of the tank and lost to atmosphere. 

During loading and unloading of crude oil tankers, the specific gravity of the crude is measured to confirm it meets the specifications for the case where payment is made on a barrel basis, or when the volume is converted into weight if the transaction is based on a price per ton (Hayward et al., 1980). 

For the above reasons, gas Is typically economic to develop only if it can be used locally, i.e. if a local demand exists. The exception to this is where a sufficient quantity of gas exists to provide the economy of scale to make transportation of gas or liquefied gas attractive. As a guide, approximately 10 Tcf of recoverable gas would be required to justify building a liquefied natural gas (LNG) plant. Globally there are few such plants, but an example would be the LNG plant in Malaysia which liquefies gas and transports it by refrigerated tanker to Japan. The investment capital required for an LNG plant Is very large typically in the order of 10 billion. 

Sales gas, which is typically made up of methane (CH ) and small amounts of ethane (C2Hg), can be exported by refrigerated tanker rather than by pipeline and has to be compressed by a factor of 600 (and cooled to -150°C). This is then termed Liquefied Natural Gas (LNG). 

Where the distance to the customer is very large, or where a gas pipeline would have to cross too many countries, gas may be shipped as a liquid. Gas has to be chilled to -160°C in a LNG plant to keep it in liquid form, and is shipped in refrigerated tankers. To condition the gas for liquefaction any COj, HjS, water and heavier hydrocarbons must be removed, by the methods already discussed. The choice of how much propane and butane to leave in the LNG depends upon the heating requirements negotiated with the customer. 

The legs of the platform can be used as settling tanks or temporary storage facilities for crude oil where oil is exported via tankers, or to allow production to continue in the event of a pipeline shut down. The Brent D platform in the North Sea weighs more than 200,000 tonnes and can store over a million barrels of oil. Topside modules are either installed offshore by lift barges, or can be positioned before the platform is floated out. 

Crude oil and gas from offshore platforms are evacuated by pipeline or alternatively, in the case of oil, by tanker. Pipeline transport is the most common means of evacuating hydrocarbons, particularly where large volumes are concerned. Although a pipeline may seem a fairly basic piece of equipment, failure to design a line for the appropriate capacity, or to withstand operating conditions over the field life time, can prove very costly in terms of deferred oil production. 

In areas where seabed relief makes pipelines vulnerable or where pipelines cannot be justified on economic grounds, tankers are used to store and transport crude from production centres. The simplest method for evacuation is to pump stabilised crude from a processing facility directly to a tanker. 

In some cases two tankers are used either alternately loading and transporting, or with one tanker aoting as floating storage facility and the other shuttling to and from a shore terminal. 

Market forces determine the demand for a product, and the demand will be used to forecast the sales of hydrocarbons. This will be one of the factors considered by some governments when setting the production targets for the oil company. For example, much of the gas produced in the South China Sea is liquefied and exported by tanker to Japan for industrial and domestic use the contract agreed with the Japanese purchaser will drive the production levels set by the National Oil Company. 

CARP Recommended Practice for Acoustic Emission Testing of Pressurized Highway Tankers made of Fiberglass Reinforced Plastic with Bolsa Cores. (ASNT)... 

The extent and manner of NDE applied in different shipyards has been the subject of a recently completed exercise within LR. The exercise involved randomly selected shipyards building ship types which included oil tankers, bulk carriers, gas carriers, container ships, ro-ro and general cargo ships. The variation in extent of applied NDE that was observed is summarised in Table 1. 

During the construction of a ship the Surveyor monitors NDE results for completeness of testing and overall quality of welding. This role includes the evaluation of checkpoints taken specifically for classification purposes but also includes the monitoring of additional checkpoints taken for quality control purposes by the builder. In the case of tankers built to LR Class since 1994 and for bulk carriers built to Class since January 1996 the Surveyor will witness the actions listed as part of the ShipRight Construction Monitoring procedure that is now mandatory. 

In order to maintain Class and to comply with international legislation a ship must undergo surveys at prescribed intervals. Ships such as tankers and bulk carriers must comply with International Maritime Organisation resolutions which require a Class Enhanced Survey Programme. This programme includes Special Surveys at five yearly intervals with close-up visual inspection and thickness measurements to be made at specified locations, the number of which increases with the age of the ship. 

The onus for the organisation of any inspection programme beyond that required by Class rests with the owner or operator of the ship. Under certain circumstances, for example, when the propagation of cracks could lead to pollution through the loss of cargo, an owner of an oil tanker operating in US coasted waters may spend a considerable amount of money on preventative inspections. 

Condition Evaluation and Maintenance of Tanker Structures", Tanker Structure Cooperative Forum. 

Chlorine is stored and transported as a Hquefied gas in cylinders of 45.4-kg or 68-kg capacity that are under pressure and equipped with fusible-plug rehef devices. Quantities in the range of 15 to 90 t are transported in tank cars having special angle valves on the manhole cover on top of the vessel. Tank barges of the open-hopper type having several cylindrical uninsulated pressure vessels are used for amounts ranging from 600 to 1200 t. Road tankers are used for capacities of 15 to 20 t. 

Formic acid is commonly shipped in road or raH tankers or dmms. For storage of the 85% acid at lower temperatures, containers of stainless steel (ASTM grades 304, 316, or 321), high density polyethylene, polypropylene, or mbber-lined carbon steels can be used (34). For higher concentrations. Austenitic stainless steels (ASTM 316) are recommended. 

The use of natural gas as a hydrocarbon source depends on transportation. Over long distances and waterways, Hquefied natural gas (LNG) is dehvered in cryogenic tankers or tmcks (see Gas, natural Pipelines). In the United States, about 22% of the fossil-fuel energy used in 1990 was gas, but in Japan this percentage was much less. 

Butanes are shipped by pipeline, lad cat, sea tanker, barge, tank truck, and metal bottie throughout the wodd. All U.S. container shipments must meet... 

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