SUBJECT: Attaching the pump and motor base plate to the foundation. The grout. 7-5

The forces and vibrations present in our rotating equipment must be absorbed by the base foundation or they will be transmitted to the mechanical seal and pump bearings, causing higher stresses and premature failure of one or both of these components. In another paper labeled "Centrifugal pump vibration readings 2-9" we learned several rules about this foundation including the one that states, "the foundation must be at least five times the mass of the hardware attached to it". You can refer to this paper for additional information

The grout, in conjunction with the anchor bolts and shims will act as the connector between the pump base and the foundation ensuring that the forces and vibrations will be absorbed and dampened as much as possible. This grout can be installed before, during or after the installation.

In the past, iron filled and gas expansive inorganic grouts were employed, causing frequent replacement. Modern grouts, when properly installed can last for ten or fifteen years, or the expected life of most pump and motor combinations. In the following paragraphs we will be looking as some of these modern grouts to help you in making your final selection.

Regardless of the brand you select you are going to have to consider the "pour ability" of the grout to avoid air pockets and voids that can become trapped between the pump base and the foundation it will rest upon. Shrinkage is another consideration along with chemical compatibility and resistance to "creep".

You should also consider that in many process plants the floors are constantly wet from pump and valve leakage, steam leaks and wash down hoses. Be sure the grout you select will not be damaged by this additional moisture.

The U.S. Army Corps Of Engineers Specification CRD-C-621-89 describes various levels of "pour ability" for non shrinking grout:

Most of the modern grouts fall into two categories:

Cement plus a natural or metallic aggregate.

Epoxy grout, consisting of three parts : a resin, a hardener, and an aggregate.

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