I have a job where I have to install some 4" PVC and 2" PVC under a bridge.

There will be 90 degree bends on each side and the bridge, which is appx. 100 feet long, has an expansion joint in the middle.

I will be hanging the conduit with beam clamps from structual steel under the bridge.

What would be the correct clamps or combination of clamps to use to allow the conduit to move?

PVC clamps are manufactured for this purpose.

See also, Table 352.44(A) provides the expansion information for polyvinyl chloride (PVC).

Table 352.44(A) Expansion Characteristics of PVC Rigid Nonmetallic Conduit Coefficient of Thermal Expansion = 6.084 × 10-5 mm/mm/°C (3.38 × 10–5 in./in./°F)