Hello everybody,

I am currently analyzing an existing old piping system, the task is to replace the old corroded spring hangers with new ones, the piping course remains as it was. For this the client requests spring hanger design via pipe stress analysis.

The problem is the following: I have no exact information about the insulation density (I only know that the material is cork, for which the density I found in literature varies significantly between 80 and 500 kg/m3 (4.994 lb/ft3 to 31.214 lb/ft3)). I was advised to use the higher value (500 kg/m3) in order to be on the safe side. However, when applying this value the SUS case is more than 250 % overstressed. And I think that using a density value that can be higher than the actual would lead to a wrong design of springs, overstressing the system by acting a very big force upwards. Could somebody give me some light on what could be a reasonable density for cork material? And does it change significantly if the material becomes very humid due to weather conditions and low operating temperatures?

Some Info on the piping system:
- Very low operating T (-90 till –120 ° C )
- Pipe Diameter 88.9 mm (3 in)
- Insulation thickness 180mm (7.1 in)

Thanks a lot

HHpiper,

Check your units on the input of density. Kg/cm3. If you input the 500 value directly, then it will cause SUS failure!
(I have done it myself.)

The above answer was good. Many times it happens by inadvertent entries of data. And it becomes difficult to detect from a large input file !!!
Now it may be analyzed using the properties of currently available insulation materials. It is a huge task to simulate the existing piping material and existing supports, guides, limits and existing springs if the information is not available. Also there must have been some assumptions at that time regarding the allowable values.
Good luck