ASME B73.3:2015 pdf free download

ASME B73.3:2015 pdf free download.Specification for Sealless Horizontal End Suction Centrifugal Pumps for Chemical Process.
5.5 Internal Drive Assembly
5.5.1 MountIng. For MDP rotating shalt designs, the inner magnet assembly shall be keyed, threaded, or permanently attached to the impeller drive shaft.
5.5.2 Balance. The rotor assembly or inner magnetic assembly shall be balanced In accordance with ISO 1940-1, Grade G63.
5.5.3 CrItical Speed. The first lateral critical speed of the rotating assembly shall be at least 120% of the maximum operating speed.
5.5.4 Fillets and Radii. All shalt shoulder fillets and radii shall be as large as practical and finished to reduce additional stress risers.
5.5.5 Internal Drive Assembly Bearings
5.5.5.1 Bearing Design. The bearing system shall be capable of absorbing all thrust and radial loads while the pump is operated within ii allowable operating range. The thrust bearing should be designed to absorb thrust in either direction; however, no design shall be offered where a change in thrust direction affects the pump hydraulic performance or reliability during normal operation. In a design that relics on thrusting in one direction during normal operation to maintain hydraulic performance and reliabilit3., reverse thrusting shall be allowed only during start-up, shutdown, or abnormal operating conditions such as vapor entrainment, insufficient NPSIIA. flow outside allowable operating region, etc.
Hearings shall be designed and applied considering fluid characteristics, unit loading, speed, corrosion. cr0- skin, wear, heat transfer, thermal cycling, fits, and material and friction characteristics.
5.5.5.2 Bearing Loading. Bearing loading, alignment, shaft deflection, surface finish, and wear-in characteristics of bearing materials shall be taken into account to prevent local surface failure.
5.5.5.3 Journals. The journals may be separate sleeves, finished shalt surface, or hard faced/coated shaft areas for both rotating and non-rotating shalt designs.
55.5.4 Clearances. Materials used for journal sleeves, thrust collars, and bearings often have significantlv different thermal espansion characteristics compared to shalt and other mating parts. Application guidelines and limits shall be established by the manufacturers for specific designs to avoid breakage or looseness under specified operating temperatures or temperature cycling.
5.5.5.5 LubrIcation. Lubricationand/orcoolingof the bearings shall be by the liquid pumped or by a clean, compatible, external fluid injection. Fluid circulation piping plan designations shown in Fig. 5.3.2.12.1 of ANSI/HI 5.1 through 5.6 shall be applied to ASME B73.3 MDP and CMP applications. A modified Plan 114 may also be applied as shown in Fig. 5.5.5.5-1.
Other configurations may be used if specified and agreed upon between the supplier and purchaser.
5.5.5.6 Heat Input. The bearings shall be provided with adequate fluid circulation and pressure that considers the maximum heat input of the drive assembly (including bearing friction) in relation to the fluid-specific gravity, the fluid-specific heat, fluid viscosity, laminar flow, turbulent flow, and vapor pressure.
The pump design shall also ensure that the temperature and pressure in the rotor chamber prevents vaporization through the full operating range of the pump from minimum flow to maximum flow while providing continuous flow through the rotor chamber for cooling and bearing lubrication.