Materials. Construction. Site erection

Compressors are generally of gray cast iron, but some makes are fabricated from mild steel. 

Compressor pistons are of cast iron or aluminium, the latter following automobile practice. 

Piping for the smaller halocarbon installations is usually of copper, because of the cleanliness and the ease of fabrication and jointing. 

Some stainless steel pipe is used, mainly because of its cleanliness, although it is difficult to join. 

Most other piping will be of mild steel. For working temperatures below - 45°C, only low-carbon steels of high notch strength are used (mainly to BS.3603). 

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On the construction site of a process plant, pipework prefabrication and site erection were already well advanced when a number of significant surface defects on piping material came to light, potentially putting into doubt the integrity and safety of the... 

Generally, if the geometry of the shell is of a size that can be shop fabricated resulting in a minimum number of segments being shipped to its erection site, steei stacks will be the least expensive. This, of course, is a very general statement in that the plate thickness and unit price of material will be a much greater consideration for taller stacks (150 ft. and above) and those which are not constructed of plain carbon steel. 

The Atmospheric Nitrogen Corporation, now operating the largest direct synthetic ammonia plant in the United States, is preparing for the erection of a large plant for this process for the production of fertilizer materials at Hope-well, Virginia. Indeed it is reported that construction has already started on the Hopewell site and that much of the equipment has been ordered and the fabrication of some completed. This plant will mark the entrance of the direct synthetic ammonia process for fertilizer production in this country and it is expected that expansion will be rapid. 

If they are to be in steel, a common arrangement is for the EPCM contractor to carry out the basic design, and then engage a specialized construction contractor to do the detailed design, procure the material, produce the shop drawings, prefabricate and then to erect the structural steelwork on site. Secondary structures can include ... 

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