Field fabrication

In general, 50.8- ana 63.4-mm (2- and 2V 2.- n) coils are the most economical for shop fabrication and 38.1- and 50.8-mm Wi- and 2-in) for field fabrication. The tube-side heat-transfer coefficient, high-pressure, or layout problems may lead to the use of smaller-size pipe. 

ME-0-JDOO5 Welding - Shop Field Fabricated Piping... 

Ducts are most often constructed of field-fabricated galvanized sheet steel, although other materials such as fibrous glass board, factory-fabricated round fibrous glass, spiral sheet metal, and flexible duct materials are becoming increasingly popular. Other duct construction materials include black steel, aluminum, stainless steel, plastic and plastic-coated steel, cement, asbestos, and copper. 

All pressure vessels should be tested, inspected, and marked in accordance with code requirements. FurUier inspection of field fabrication vessels may include Uie radiography of all seams and oUier pertinent tests. 

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. 

The suggested bulk material factors are applied to direct equipment costs, whereas the bulk labor factors apply to the corresponding bulk material item. Because the distributive factors are based on larger scale field built plants, FETC applies an additional factory fabrication adjustment to reflect a more modular construction approach requiring less field fabrication as would likely be the case with smaller plant configurations. This approach is illustrated in reference (18). 

In Jnly 2002, the US EPA issued a final rule amending 40 CFR 112 which inclnded differentiation of shop-fabricated from field-fabricated ASTs. The mle also includes new subparts outlining the requirements for varions classes of oil, revises the applicability of the regnlation, amends the requirements for completing SPCC Plans, and makes other modifications. 

Piping - field fabrication, erection, heat tracing, testing. 

Non-operating field leak tests or field pressure tests on piping and field fabricated equipment as required by the specifications. Disposing of test media in accordance with the Owner s instructions. Removal of test blinds. 

All the major process equipment, such as vessels, reactors, columns, furnaces, heat exchangers, coolers, pumps, compressors, motors, fans, turbines, filters, centrifuges, dryers, etc., including field fabrication and testing if necessary ... 

Tank Coils Pipe tank coils are made in a wide variety of configurations, depending upon the application and shape of the vessel. Helical and spiral coils are most commonly shop-fabricated, while the hairpin pattern is generally field-fabricated. The helical coils are used principally in process tanks and pressure vessels when large areas... 

Welding Filler Metal Wrong filler metal with poorer corrosion resistance (317L stainless steel) was used in alloy C-276 piping Product leakage at welds required shutdown and replacement of piping Check certification of weld filler metals used for field fabrication. For critical applications conduct chemical analysis on sample... 

Field fabricated for sizes above 5 MW total heat load. 

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