Every installation needs an adequate foundation. For pumps, there are three basic classes of equipment that require different styles of foundations. An excellent source for further information is Process Industry Practices (PIP) document REIE686 which is a joint document with API which titles it RP686. PIP has a supplemental document REIE686A that has additional information.
I will cover sealless pumps first. Sealless pumps do not have a coupling so there is no need to maintain alignment. All a sealless pump needs is to be held level. Therefore, stilt mounting is the preferred method of supporting sealless pumps. This can be done with all thread and double nutting. The manufacturers also provide stilt mounting systems that will make the installers life a little easier. The cost is reasonable and you know they will fit the pumps and work. An additional benefit of stilt mounting is that the pump is free to move and will help relieve pipe stress rather than be a fixed anchor point.
Conventional sealed centrifugal pumps do have couplings that need the alignment to be maintained within tight tolerances to obtain maximum life of the equipment and keep life cycle costs to a minimum. Block foundations are necessary to accomplish this. For ASME pumps there are precast polymer bases that provide good support and are massive enough to absorb vibrations.
The other option, for all sealed centrifugal pumps, is a conventional concrete block foundation. Industry experience shows that a block that weighs 5 times as much as the pump, motor, and baseplate will absorb all dynamic and static forces and last several years provided it is properly corrosion protected. This block will be oversized relative to one that is optimized for soil conditions, piping loads, and all other forces. However, the engineering costs to design an optimized block far exceed the cost to build this oversized inefficient foundation. Anchor bolts will be covered in a future narrative.
Reciprocating pumps also require a block foundation to absorb dynamic forces. These forces are much larger that those encountered in centrifugal machines so a larger foundation is required. Industry experience has shown that a block that weighs 10 times the combined weight of the pump, gearbox, and motor will provide many years of service.
Again, PIP, and API 686 guidelines provide additional information and details.