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Pump Nozzle Loading · Standards and Codes
missible nozzle loading [1].
7.5 Pump Nozzle Loading
As the loading profile for each pump nozzle is made up of three different forces and moments, it is not possible to specify theoretical nozzle loading limits for all conceivable combinations. Therefore, operators either need to check whether the nozzle loading imposed by the system is still within the pump’s permissible limits, or have to contend with the considerably reduced general limits specified in several national and international standards and codes (EUROPUMP brochure “Permissible flange forces and moments for centrifugal pumps”, 1986; API 610; ISO 5199).
A centrifugal pump mounted on the foundation should not be used as an anchorage point for connecting the piping. Even if the piping is fitted to the nozzles without transmitting any stresses or strains, forces and moments, summarized as nozzle loading, will develop under actual operating conditions (pressure and temperature) and as a result of the weight of the liquid-filled piping. These cause stresses and deformation in the pump casings, and above all changes in coupling alignment, which, in turn, may affect the pump’s running characteristics, the service life of the flexible elements in the shaft coupling, as well as the bearings and mechanical seals. For this reason limits have been defined for per-
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7.6 National and International Standards and Codes A series of national standards and other technical codes have been introduced in Germany since the early sixties which govern the dimensions, manufacture, design, procurement and use of centrifugal pumps. Many of the requirements laid down have been included in European and international standards and codes. Drawn up by both operators and manufacturers, these are now wellestablished in virtually all sectors of industry using or producing pumps. The most important standards are tabulated in Fig. 80 on page 70.
Permissible moments Mmax at the flange reference plane
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Fig. 79 shows the permissible nozzle loading for single-stage volute casing pumps to ISO 5199 (solid line for pumps on
grouted baseplate, broken line for pumps on non-grouted baseplates).
Fig. 79: Permissible moments Mmax at the flange reference plane, as well as permissible forces FH,max (at x,z plane) and FV,max (in y direction) to ISO 1599 for single-stage volute casing pumps made of ferritic cast steel or nodular cast iron at room temperature. Lower numerical values apply to austenitic cast steel, lamellar graphite cast iron or higher temperatures.
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