Piping maintenance

The cylinders are arranged on the main frame of the compressor to provide balanced crankshaft power loading (when possible), access for maintenance, piping convenience, and floor space to suit plant layout. Common designations by position of the cylinder are... 

Examples will cover maintenance inspection such as corrosion detection in piping and tanks, but also routine weld inspection. The need for acceptance criteria for weld defects adapted for modern NDT techniques will be highlighted, because these form (in many cases) the key to benefit. 

In addition, NDT plays an important part in industrial maintenance. During plant shutdowns for instance, many thousands of ultrasonic wall thickness measurements are taken on piping, vessels, furnace tubes etc. All these thickness readings have to go into extensive data bases, and this process is, thanks to modem computers and data loggers, ever more automated. 

Corrosion of reactors used for functionalization and ia pipes and valves along transferlines for sulfuric acid is a problem that results ia maintenance shutdowns. Sufficient agitation is needed to keep the resia beads fluidized duting sulfonation. As for copolymer kettles, transfer lines should be sufficiently large to allow reasonably rapid transfer of Hquids and resia slurries. 

Storage areas for maintenance, janitorial, and other service organizations must be provided. Safety items such as fire extinguishers, firehose cabinets, safety hoops on permanent ladders, guard rads, shielding for acid pumps, clearance for electric panel boards, etc, are needed. Manholes and cleanouts for sewer pipes within the facility as well as in the landscape and parking areas should be provided. 

Corrosion. Anticorrosion measures have become standard ia pipeline desiga, coastmctioa, and maintenance ia the oil and gas iadustries the principal measures are appHcation of corrosion-preventive coatings and cathodic protection for exterior protection and chemical additives for iaterior protectioa. Pipe for pipelines may be bought with a variety of coatiags, such as tar, fiber glass, felt and heavy paper, epoxy, polyethylene, etc, either pre-apphed or coated and wrapped on the job with special machines as the pipe is lowered iato the treach. An electric detector is used to determine if a coatiag gap (hoHday) exists bare spots are coated before the pipe is laid (see Corrosion and corrosion control). 

Figure 12 shows the plan and elevation views of a process unit piping (9). A dmm is supported off the piperack. Heat exchangers are located far enough back from the support columns so that they are accessible and their shell covers can be removed. Pumps are located underneath the piperack, but sufficient room is provided for maintenance equipment to access the motors and to remove the pump if necessary. The motor is always oriented away from the process equipment and located on that side of the piperack. Instmment valve drops are shown supported from the columns. The instmment trays themselves mn on the outside of the support columns. Flat turns are only made from the outside position of the piperack. Nozzle-to-nozzle pipe mns are made whenever possible. Larger lines are located on the outside of the piperack. Connections to nozzles above the rack are made from the top... 

Pressure Vessels and Piping. Some of the most critical components of a chemical plant involve pressure vessels. A thorough knowledge of the American Society of Mechanical Engineers (ASME) Pressure Vessel Code (75) is essential for design and maintenance of chemical plants. Some states have their own codes, which usually conform closely to the ASME version (see High pressure technology Tanks and pressure vessels). 

Another option is the dry-pit design (Fig. 7c). This pump is installed in a dry pit and coimected to a weU via a pipe. Because the dry pit is usually dug out wider than the wet pit, Tenough room is available for pump maintenance, troubleshooting, and repair without pulling the pump to the surface for servicing. 

An axially spHt pump typically has a volute, and offers the advantage of easy maintenance because of quick upper-half casing and rotor removal that is similar to a single-stage version. The piping, attached to the no22les located at the lower half of the casing, remains undisturbed. 

Reduced Emissions and Waste Minimization. Reducing harmful emissions and minimizing wastes within a process by inclusion of additional reaction and separation steps and catalyst modification may be substantially better than end-of-pipe cleanup or even simply improving maintenance, housekeeping, and process control practices. SO2 and NO reduction to their elemental products in fluid catalytic cracking units exemplifies the use of such a strategy (11). 

Isolation A means for pressure-isolating control valves, pumps, and other piping hardware for instaUation and maintenance is another... 

Maintenance shops—electric, piping, sheet metal, machine, welding. Raw-material and finished-product handling equipment—elevators, hoists. 

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