Spring Hanger Problems in steam piping of Power Plants

I have been involved in studying pipe and hanger behavior of 110 to 500MW power
plant in India.

Power plants that have run for over 20 years have hanger problems in the Main steam,
Cold Reheat and Hot reheat steam pipelines.Several Hangers are either topped out or
bottomed out.

As per studies carried out in Cold and hot condition of a several power plants, it has
been observed that at least 25% of total number of Spring hangers have shown a travel
which is in deviation from design.

And it is suspected that undesirable forces are being transferred to the Turbine end
thereby effecting the expansion of the Steam Turbine.

Possible causes are the end of spring life and changes in piping layout, due to the
effect of loss of elasticity of the piping.

Would like technical opinion re short term and long term measures that can be taken
to resolve the hanger problems.