A Bad Check Valve Did This?

Recently, I ran into a situation where a client was replacing temperature regulators at a fast rate. The regulator was responsible for feeding steam into their feed water tank as a method of preheating the feed water to 180F. 

One of the faulty regulators was sent back to the factory and they found a damaged bellows. The only way this could happen was by water hammer. The question became how the water hammer was happening inside the body of the valve. Thanks to some great advise from a steam fitter friend of mine, Archie, we found the cause. 

There was a check valve installed after the regulator. My client isolated the steam so there was no steam entering the body of the regulator. He proceeded to break the union upstream of the regulator and check if water was coming out of the regulator body. Surely, water did pour out which meant when there was no call for steam, the check valve was allowing feed water to flow backwards into the body of the steam regulator.  When there was a call for steam, it found its way into a flooded valve body and thus hammering and damaging the valve. 

In addition to replacing the faulty check valve and damaged bellows, the client repiped the line so the check valve and regulator were above the waterline of the feed water tank as an additional precautionary method.  

Often times, a reoccurring problem is a tell-tale sign of a different issue. Especially with simple mechanical devices. 

10uta