Metallurgy, pumps

Changing the pump metallurgy to a more corrosion- and cavitation-resistant material, such as stainless steel, is a potential solution to this type of problem. Note, however, that all other cast iron pump components that have sustained graphitic corrosion should be replaced to avoid the possibility of galvanic corrosion (see Chap. 16) between retained graphitically corroded cast iron components and new components. 

Packing corroded away (twice). Poor separation. Pieces of packing in pump suction. Wrong metallurgy specification error. 

The metallurgy selected for construction of a firewater pump is dependent on the properties of the water source to be used. For fresh water sources (i.e., public water mains), cast iron is normally adequate although bronze internals may be optional. Brackish or sea water utilization will require the use of highly corrosion resistance materials and possibly coatings. Typically specified metals include alloy bronze, monnel, ni-resistant, or duplex stainless steels sometime combined with a corrosion resistant paint or specialized coating. 

Interaction parameters for polymer blends, 20 322 in surfactant adsorption, 24 138 Interaortic balloon pump, 3 746 Intercalated disks, myocardium, 5 79 Intercalate hybrid materials, 13 546-548 Intercalation adducts, 13 536-537 Intercalation compounds, 12 777 Intercritical annealing, 23 298 Interdiffusion, 26 772 Interdigitated electrode capacitance transducer, 14 155 Interesterification, 10 811—813, 831 Interest expense, 9 539 Interface chemistry, in foams, 12 3—19 Interface metallurgy materials, 17 834 Interfaces defined, 24 71... 

Pumping systems, evaluation of, 21 56 Pump manufacturers, U.S., 21 87t Pump metallurgy, upgrading, 21 86 Pumps, 21 54-91... 

Bearings and sealing Ball bearings especially for high speed high stiffness applications No or low lubrication (vacuum pumps, dental drill handpieces) Under corrosive conditions (food ndustry chemistry metallurgy) high and low temperatures... 

A wide variety of excellent pumps is available in the chemical industry. It is sometimes a problem to choose the best from the large number available. This discussion will be limited to centrifugal pumps. Assuming that one has sized the pump, decided on a centrifugal pump, and chosen a suitable list of vendors, the main choices involve (1) metallurgy, (2) seal-less pumps versus conventional centrifugal pumps, and (3) the type of seals for conventional pumps. 

Metallurgy 22 Cast iron should not be used for flammable or hazardous service. The minimum metallurgy for centrifugal pumps for hazardous or flammable materials is cast ductile iron, type ASTM A 395, having an ultimate tensile strength of about 60,000 psi. 

Don t use cast iron for flammable or hazardous service unless there is no other choice. In very few cases, only cast iron is available. This is true for large double-suction water pumps used by municipalities where types other than cast iron are not readily available. The minimum metallurgy for centrifugal pumps for hazardous or flammable materials is cast ductile iron, type ASTM A 395, having an ultimate tensile strength of 60,000 psi. This metal is not brittle at ordinary temperatures. Often, special alloys are required because of corrosion. In no case should brittle materials be used for a pump if other choices are available. 

Estimate based on pump capacity, usually 2 1/2-in. average. Pondered average based on plant metallurgy. 

Figure 19. Rotor and stator assembly of progressive cavity pump. (Reproduced with permission from reference 113. Copyright 1988 Canadian Institute of Mining, Metallurgy, and Petroleum.)...

Hazardous Decomp. Prods. Heated to decomp., emits toxic fumes of Hg HMIS Health 3, Flammability 0, Reactivity 1 Uses Amalgam dental fillings catalyst electrical apparatus cathodes for prod, of chlorine and caustic soda instrument indicator fluid thermometers barometers mercury vapor arc lamps extraction metallurgy mirror coating boilers coolant and neutron absorber in nuclear power plants vacuum pumps... 

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