Pipeworks 2.0 is the sequel to the original Pipe Construction Set. It allows you to build virtually any combination of pipe networks, and boasts very high quality assets. The pack includes one Hi-res texture map, with normal, specular, and diffuse included for next gen games. There are also 13 high quality models included, including a wall bracket to support your pipes on walls or ceilings.
The polycounts of the models are somewhat high, so they may not suit a mobile game well (or similar). However, the bolts can be taken out to reduce polycounts of needed.
The models come in the following formats:
Lightwave LWO Wavefront OBJ 3d Studio 3ds Direct X file