Pipe fittings resistances

Fittings, pipe, resistances, 95, 98-100 Fixed bed solid catalysis, 596 name reactor, 573 Flash conditions, 375-377 example, 378... 

Austenitic-ferritic type with general corrosion resistance similar to type 316 but with better resistance to stress-corrosion cracking capable of age hardening. Valves, valve fittings, piping, pump parts. 

Unplasticized polyvinyl chloride pipes and fittings - Chemical resistance with respect to fluids. 

The flow resistance of pipe fittings (elbows, tees, etc) and valves is expressed in terms of either an equivalent length of straight pipe or velocity head loss (head loss = Kv /2g ). Most handbooks and manufacturers pubHcations dealing with fluid flow incorporate either tables of equivalent lengths for fittings and valves or K values for velocity head loss. Inasmuch as the velocity in the equipment is generally much lower than in the pipe, a pressure loss equal to at least one velocity head occurs when the fluid is accelerated to the pipe velocity. 

Pipe fittings require quite high tensile and creep resistance they are thus molded from compounds that have less melt flow than for thin-waHed housings. Plasticized compounds are injection-molded into a variety of parts requiring elastomeric properties. 

Storage and Handling. The acid should never be allowed to stand in a line completely sealed between two closed valves or check valves. Excessive pressure caused by thermal expansion of the Hquid can cause leaks or pipe mptures. AH lubricants and packing materials in contact with chlorosulfuric acid must be chemically resistant to the acid. Elanged connections are recommended over screwed fittings and flange guards should be used. 

Friction Head This is the pressure required to overcome the resistance to flow in pipe and fittings. It is dealt with in detail in Sec. 5. 

Plain-end pipe used for socket-weld joints (Fig. 10-126) is available in all sizes, but fittings and valves with socket-weld ends are limited to sizes 3 in and smaller, for which the extra cost of the socket is outweighed by much easier alignment and less skill needed in welding. The joint is not so resistant to bending stress as the butt-welded joint but is otherwise equal, except that for some fluids the crevice between the pipe and the socket may promote corrosion. ANSI B16.il—1973,... 

Polypropylene Polypropylene (PP) pipe and fittings have excellent resistance to most common organic and mineral acids and their salts, strong and weak alkahes, and many organic chemicals. They are available in sizes V2 through 6 in, in Schedules 40 and 80, but are not covered as such by ASTM specifications. 

The largest single use area for UPVC is for pipes and fittings. One particular area here is in chemical plant. It is of course necessary to check that all of the components of the PVC compound will be resistant to any of the chemicals with which the plant is liable to come into contact (at the appropriate temperatures) and also that additives will not be leached out by these chemicals. Particular uses are in acid recovery plant and in plant for handling hydrocarbons. 

By virtue of its chemical and thermal resistances, borosilicate glass has superior resistance to thermal stresses and shocks, and is used in the manufacture of a variety of items for process plants. Examples are pipe up to 60 cm in diameter and 300 cm long with wall tliicknesses of 2-10 mm, pipe fittings, valves, distillation column sections, spherical and cylindrical vessels up 400-liter capacity, centrifugal pumps with capacities up to 20,000 liters/hr, tubular heat exchangers with heat transfer areas up to 8 m, maximum working pressure up to 275 kN/m, and heat transfer coefficients of 270 kcal/hz/m C [48,49]. 

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