A manifold assembly configured for use with a fluid end used in oil and gas operations. The manifold assembly comprises upper and lower manifolds supported on side posts such that the manifolds and posts define a central opening. In operation, the fluid end is positioned within the central opening such that the manifold assembly surrounds the fluid end. The manifold assembly is not attached to the fluid end other than flexible conduits interconnecting the fluid and the manifolds. The manifold assembly is modular and when assembled, may be moved together as a single unit.