Hi Pat,

Is this seam welded piping?

Some thoughts: Sixteen years is a bit early for that degree of creep elongation. Investigate the rest of the hangers. Before (steam flow direction) the HR piping comes to the horizontal run you are describing it likely comes down vertically from the reheat outlet header. At some elevation on that vertical riser there should be a rigid support (likely a trapeze). Strip some insulation and look that rigid support over closely for damage or distortion. If there is no rigid support on that vertical riser (“full floating system”) you will have to look at all the rest of the HR spring hangers. The hangers on the horizontal run might be badly affected by heat (springs “relaxed”) and perhaps they are no longer providing the proper amount of reactive force (can you test one or two with a dynometer?).

I believe your thoughts about “this pipe has NOT gotten heavier” are correct. If you add spring hangers, you will further upset the balance unless you can quantify the current amount of supporting reaction the old hangers are providing and supplement that with spring hangers that are well chosen to provide the SAME support reaction as was there originally. Be sure to check the spring hangers at the HR inlet (to the turbine) valves to see if they have also “bottomed out”. If only one spring hanger has failed, the entire balance would be upset. Any chance that a stop valve was added after original construction? Could here have been a new branch connected?

One outside possibility is that the top of the horizontal HR pipe somehow was deluged by “cold” water at some point and is now “bowed” due to plastic deformation due to differential expansion (top to bottom). Or conversely, a puddle of condensate formed on the inside of the pipe on shutdown and bowed the pipe (in the other direction) before the "unwetted" upper part of the pipe could cool.

Regards, John.