Turn the fake wood beams over and measure the hollow inside of each beam. Cut a block of wood, using an electric saw, that is 2 inches thick, as wide as the width inside each wood beam and around 6 inches long.
Run a stud finder along the ceiling or walls behind the pipe. Mark each place where you find a stud with a chalk mark. Attach a wood block every 3 to 6 feet along the ceiling or wall that runs behind the pipe. Use an electric drill to screw the wood block into the wall or ceiling.
Measure the length of pipe you plan on covering, and cut your fake wood beams to that exact length with an electric saw. Run a thin layer of construction adhesive around the edges of the underside of the fake wood beam; this is the side that will be touching the wall or ceiling.
Press the fake wood beam around the pipes, fitting it snugly around the wood blocks. Hold it in place for five minutes or so, giving the glue time to set.
Drill screws through the fake wood beam and into the blocks of wood underneath. Insert screws on either side of each block of wood.
Wipe off any adhesive that may have oozed out, using a damp cloth.