Field erection

However, packaged boilers have a limited size range. Thus, field-erected boilers are stiU required for most large industrial and utiUty iastakations. 

Cone-Roof Tanks. Cone-roof tanks are cylindrical shells having a vertical axis of symmetry. The bottom is usually flat and the top made ia the form of a shallow cone. These are the most widely used tanks for storage of relatively large quantities of fluid because they are economic to build and the market supports a number of contractors capable of building them. They can be shop-fabricated ia small sizes but are most often field-erected. Cone-roof tanks typically have roof rafters and support columns except ia very small-diameter tanks when they are self-supporting (see Fig. 4b and c Table 3). 

Based on a sui vey in 1994 for storage tanks, the prices for field-erected tanks are for multiple-tank installations erected by the con-trac tor on foundations provided by the owner. Some cost information on tanks is given in various references cited in Sec. 25. Cost datavaiy considerably from one reference to another. 

In general, air conditioning equipment can be classified into two broad types central (sometimes called field erected) and unitary (or packaged). 

Dryer assembly Packaged unit Packaged unit Field-erected unit Field-erected unit... 

Types of Combustors The three main classes of facilities used to combust municipal refuse are mass burn, modular, and RDF-fired facilities. Mass-burn combustors are field erected and generally range in size from 50 to 1000 tons/day of refuse feed per unit (Fig. 25-64). Modular combustors burn waste with little more pre-... 

For package versus field erected boilers, field erected are usually selected when conservative design and high... 

Gear boxes are used on just about all large field erected cooling towers and many factory assembled towers- all of the propeller ty e fan, draw-through type. Almost all are right angle gear drives with the input shaft horizontal and the output... 

The flare tip and associated equipment shall be piece marked and the electrical terminals shall be ceded to facilitate field erection. 

Usually must be field erected except for very small sizes. 

Steam from a field-erected boiler almost always contains significantly less entrained water than the preceding figures because of the greater sophistication of steam separation devices. However, some caution is required because even dry steam from an efficient HP boiler may contain volatilized salts (such as chlorides and silica) through the process of steam stripping. 

They may be supplied as package (preengineered) boilers, job-built boilers (fully factory constructed and then cut into pieces for difficult access sites), or field-erected boilers. All very large WT boilers are field-erected but often arrive on-site in modular form. 

Smaller WT boilers are available as shop-assembled packaged units, whereas large boilers are constructed in sections and shipped to site for field erection. The largest field-erected boilers can provide steam, superheated to 1,100 °F (593 °C) and at pressures in excess of 2,900 psig. Some boilers operate at supercritical pressures (N.B. critical pressure is 3,208.2 psia). 

Shop-assembled, packaged boilers, developed during the 1940s were designed to meet the significant wartime era demand for high output, mainstream industrial use at lower cost than field-erected units. 

They tend to be bottom-supported and can be supplied either as packaged or modular (field-erected) units. Industrial boilers may be designed to bum cmshed coal (PF), oil, gas, or a combination of oil and gas with a solid fuel. 

These large industrial manufacturers (paper mills, steel works, oil refineries, petrochemical facilities, etc.) tend to employ either high capacity (200,000-800,000 lb/hr) packaged D-type boilers, or field-erected, two-drum, single gas-pass industrial power boilers, which produce steam at up to 1,800 psig. 

Typically, for any given pressure, industrial packaged boilers operate at higher heat-flux rates than field-erected boilers, This requires that the package boiler FW quality should be substantially better (i.e., lower overall TDS and lower levels of silica and sodium). Appropriate MU water pretreatment may, for example, necessitate the use of twin bed and mixed bed demineralization ion exchange, or RO and mixed bed (in addition to mechanical deaeration and other processes). 

A mle for all industrial WT boilers is that they should receive as good a quality of MU water to the FW system as local conditions dictate and the business can economically support. However it is not unusual in some parts of the world to find large field-erected industrial... 

In the McCoy table of recommended concentrations of boiler salines, the guidelines for pressures from 100 to 900 psi apply to conventional field-erected boilers with moderate rates of heat transfer, say, 50,000 Btu/hr/ft2. At high rates characteristic of packaged boilers, large amounts of insoluble material cannot be managed effectively by any dispersant presently available. 

Field erected steam boiler (Water-tube boiler) CS Steam generation (kg-h-1) 20,000 3.28 x 105 10,000-800,000 0.81... 

Liquids are most economically stored in bulk containers. When large quantities above 25,000 gal must be stored, the tanks should be constructed to the dimensions given by the American Petroleum Institute Standards (see Table 5-2). These tanks must be field-erected. For smaller quantities more economical shop-constructed tanks should be specified. Field fabrication is always more expensive than shop fabrication. A shop-constructed item, in general, must be less than 11.5 ft (3.5 m) in diameter, so that it can be shipped by truck or train. For any piece of equipment that must be shop-fabricated, or for which the cost of field construction is prohibitive, this limitation should be noted. When barges may be used for transportation, this limitation does not hold. 

Volume of each of 10 storage units=22,700 ft3 If each were 11.5 ft in diameter, they would be 218 ft high. This is impractical, so field-erected silos are necessary. Assuming L= 1.5 D, the diameter is 26.8 ft. 

Proper placing of equipment can result in large savings during the construction of the plant. For instance, large columns that are field-erected should be located at one end of the site so that they can be built, welded, and tested without interfering with the construction of the rest of the plant. 

ASIC EQUIPMENT AVERAGE (Mild steel equipment) High percentage of corrosion materials and other high unit cost equipment involving little field erection 12.5/7.5 11 5/6.7 10.8/6 10/5.5 9.2/5.2 8.5/5 8/4.8... 

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