Pipe Support Concrete Base Design

Contact a local civil engineer who has experience in concrete footing design.

For a simplistic approach, you need to know the allowable bearing pressure that the soil can support. If you divide the total weight by this bearing pressure, you will have an area for the footing. The footing must then be designed for thickness and reinforcing. There are some other issues regarding soil types, settlement, frost, etc.

Dik

Not sure exactly what the application is but don't forget to take into consideration your wind forces...

Don't assume vertical forces only. Temperature changes in pipes can exert high lateral forces to the anchor points. Other pipe supports can have slide-type supports to minimize lateral forces, but they sometime freeze up (ice or rust) and can transmit lateral forces, unintendedly.

The piping which will be supported is inside a water treatment facility, so no freezing or wind forces will be present. The base for the pipe support will be placed upon the existing 12" concrete floor.

You are potentially opening a can of worms. Liability wise you are trying to turn a concrete slab in to a footing. That slab may or may not be able to support that vertical force. Also, I would never assume that anything in an industrial setting would only see vertical force. I have seen several "accidents" where a forklift has ran in to a column or pipe. If you are doing this as an inside job for the plant without any "real" liability, you might be able to assume 250 psf allowable for your floor slab and size your "footing" based on this. Then your depth would be determined by your bolt length. If your calculated loads are small enough I would think a minimally reinforced pad would suffice with dowels drilled in to your existing slab. If your loads are sufficiently large you may want to consider cutting out an area fo slab and pouring directly on the soil.

Have you considered the possibility of lateral loads due to seismic activity? Check the local governing codes.