How steam pipe blowing works
Most large college campuses use steam plants to provide heating energy to multiple buildings through underground piping systems. As universities expand, so do steam plant demands. Newly constructed buildings go up, new piping is dug and connected to the plant for steam energy. Pipelines must be clean and free of debris such as weld slag, loose foreign materials, or rust. This is accomplished by blasting high-energy steam through the piping and clean steam is achieved.
This process is called pipe blowing.
“Normally, when steam systems are turned on, any debris is collected at the strainers but this may not entirely clean the system,” says Doug Davidson, Southern Air Mechanical Vice President. “The pipe blowing method uses the system steam pressure and velocity to clean any debris and manufactured coatings from the inside of pipe. And it will certainly grab your attention if you are ever present to witness this procedure!”
When new piping is installed in the ground and welded together, all kinds of dirt, gunk and grime find their way inside. Pipelines can be miles long and in Virginia Tech’s case, they had 170-feet of new piping connecting their steam plant to the new Creativity and Innovation District (CID), currently under construction. CID’s mechanical systems powered by the plant could not be started until the Southern Air team verified clean steam was in-fact flowing through the pipes.
Pipe blowing is a hazardous procedure calling for unique safety requirements. The steam is blown into the atmosphere from an exit pipe aimed in a safe direction. A 100psi steam system can produce a noise level comparable to a jet engine with an exiting steam temperature exceeding 330°F. To mitigate these safety concerns, a muffler is installed around the exit piping to reduce the noise. The steam discharge is placed vertically to the atmosphere and far enough away from buildings and people so the steam’s temperature can cool to a safe temperature.
Brass Target
The inspection process involves a large piece of brass placed near the steam’s exit point. When the soft metal is super-heated from 330° steam blowing through 6-inch pipes at 100 psi, it allows for tradespeople to conduct an accurate examination of the blow down. They repeat the procedure until the brass piece is free of any sediment.
Virginia Tech’s steam pipe blowing procedure was quite a sight to see, even on a chilly morning. Tradespeople watched in the falling snow, peeked through windows, as did a few students passing by. It’s not every day you get to witness such a cool feat of engineering in this unique cleaning method.