Sagging steam piping 3

[seanmc]

I have been asked to recommend a plan of action to address a section of steam piping of pressure 14MPa which is sagging. The spring hanger has bottomed out, the spring is fully compressed. Basically the plant people want to lift it back up again, but I would not want to overstress the pipe in the other direction. We have access to the Caesar stress analysis program. Any advice on how to attack this problem would be much appreciated.

 

[MJCronin]

seanmc,

Let me see...... 14 MPa is about 2030 psig ? This means you are probably dealing with a high pressure, high temperature line in a central steam station ?

Is this an older "main steam system" in an old power plant and are you a young engineer assigned to take responsibility for a condition that has probably been around for several years ? The old bastard that runs the maintenance department probably wants this done right away. Is this right ? I am just guessing here...

Steam lines at elevated temperatures don't last forever. They are subject to missalignment and creep over the years. "Sagging" main steam systems at old plants are somewhat common. An engineering firm that does this kind of evaluation is called APTECH out of California. Another firm called Thielsch Associates out of Rhode Island (USA) also can help.

Steam piping repair should only be done when the unit is down for an outage. Jacking a system into place while operating is asking for trouble.

The typical solution is to inspect, then cut the piping, realign and buy a new spring hanger......... of course there is no money in the budget to do this. (and that old bastard wants an answer right away)

Call a consultant and Good Luck !

MJC