That evidence also showed that Georgia Kraft Company did not incorporate in its design of the steam system the recommendations made by B. E. K. Under those circumstances, we see absolutely no causal connection between any conduct of B. E. K. and the failure of the expansion joint and consequent death of appellants' decedents. The grants of summary judgment to B. E. K. were proper. Winslett v. Cooper, Carry Assoc., 143 Ga. App. 202 ( 237 S.E.2d 698). 3. As the bases for Flo-Control's liability, appellants contend that Flo-Control was involved in the design and manufacture of the expansion joint; that Flo-Control failed to choose a reliable manufacturer for the expansion joint; that Flo-Control negligently failed to warn potential users of the dangerous nature of the expansion joint.