Mains underground

An anti-gas butterfly valve in a main underground ventilation airway at Spring Quarry. One of the 120" diameter induction fans can be seen in the background. 

Health problems are documented for gold miners who worked mainly underground with litUe exposure to elemental mercury in Australia, North America, South America, Europe, and Africa. Major problems examined included life expectancy, cancer frequency, and pleural diseases. Health problems of miners who worked mainly on the surface and with extensive exposure to elemental mercury owing to its use in amalgamating and extracting gold are reported extensively in Chapter 19. 

The Institute has many-year experience of investigations and developments in the field of NDT. These are, mainly, developments which allowed creation of a series of eddy current flaw detectors for various applications. The Institute has traditionally studied the physico-mechanical properties of materials, their stressed-strained state, fracture mechanics and developed on this basis the procedures and instruments which measure the properties and predict the behaviour of materials. Quite important are also developments of technologies and equipment for control of thickness and adhesion of thin protective coatings on various bases, corrosion control of underground pipelines by indirect method, acoustic emission control of hydrogen and corrosion cracking in structural materials, etc. 

The demand for gas is highly seasonal. Thus pipeline companies economi2e by si2ing production faciUties to accommodate less than the system s maximum wintertime demand. Underground storage faciUties are used to meet seasonal and daily demand peaks. In North America, gas is stored in three main types of underground formations depleted oil or gas fields, aquifers that originally contained water, and caverns formed by salt domes or mines. 

A vital part of the process system for each of the plants includes a turboexpander-compressor set. This turbomachinery string has two main functions. The first function reduces the pressure and temperature of the incoming gas to facilitate separation of the methane. The second function raises the pressure of the methane after it leaves the fractionation tower and is transferred directly to the customers through an underground pipeline. 

Natural gas is transmitted in pipelines first across the country under high pressure m transcontinental pipe lines to local gas utility companies. The gas utility company reduces the pressure and distributes the gas through underground mains, and again reduces pressure from the street main into the home. 

Industrial process applications where compressive strength is needed. Also used in underground pipework district heating mains. 

Coal tar enamel This is derived from the coking of coal and is further distilled to produce coal tar pitches. It is used for hot application on-site. It will crack and craze if exposed to sunlight but has been employed successfully for over 50 years for the protection of underground or immersed structures. The main use is now for the exteriors of buried or immersed pipelines. Different types of enamel are available to give various degrees of heat resistance. It is now generally used for pipelines below 155 mm diameter. 

Hard underground waters, mainly in the East and South of England, mostly from chalk, sandstone or limestone strata. 

A carefully planned network of shafts, drifts, and raises are the requisites of a producing underground mine. The word development stands for the preparation of this network. In normal development one can recognize four different kinds of rock excavation and they are shafts, drifts, raises and inclines. The main aim of provision of a shaft is to provide access to or a connection with underground. This access may be utilized for a variety of purposes hoisting rock and ore, personnel and material transport, ventilation, etc. Most modem shafts... 

In the U-pipe a heat (or cold) carrier is circulated to store or discharge thermal energy into or out of the underground. The storing process is mainly... 

The third cleanup program, also authorized by the RCRA, addresses contamination resulting from leaks and spills (mainly petroleum products) from underground storage tanks (USTs). This law has compelled cleanup activities at many UST sites. By February 1999, over 385,000 releases had been reported, 327,000 cleanup projects initiated, and 211,000 projects completed. 

Considering reducing the water mains pressure or isolating areas when not in use, if leaks and unaccountable losses are a problem from underground piping systems and so on... 

An American Salt Company plant and the Dow Chemical Company s Midland plant also benefit directly from each other s presence. Dow found that after recovering bromine from brine it had more salt left than it desired. American Salt needed salt. By locating next to Dow s plant it was able to buy this salt stream for less than it would cost to mine it or pump it from natural underground reservoirs. In turn, Dow was able to sell an unwanted stream that it would otherwise have had to pump back into the ground. The American Salt plant is typical of many satellite plants. These are plants that either use a by-product or a waste stream from another plant or are built mainly to supply a needed chemical to an adjacent plant. The nearby presence of another plant determines their location. 

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