An Engineering Extension energy feature

Here's what makes steam pipes noisy

By Tom Logan
If you have been in an older building during the winter, you know that steam systems are often noisy.

It may be caused by the steam flowing in the piping, or the piping itself as it expands about 1 inch per 100 linear feet when heated from 70 to 220 degrees. Expansion noise occurs only when you first start the system.

Another noise problem is water hammer. It results when water trapped in the supply piping comes in contact with steam. The steam pushes the water in front of it at high speed (up to 90 mph). The water causes the loud noise when it hits a turn in the piping. In addition to the noise it creates, water hammer eventually deteriorates piping and equipment.

You can eliminate water hammer by removing condensate from the supply piping. Do this by sloping the piping at least 1/4-inch per foot in the direction of steam flow. Where the piping changes from horizontal to vertical, there must be a drain point (called a drip leg) with a steam trap where you can drain the condensate from the piping. Also, long, straight runs of piping should have drip legs every 200 feet.

| Steam heating |