pump support settlement

[106coral]

Hello,

I was requested to come up with solution to prevent settlement of vertical in-line pump support due to ground heaving.
As reuslt of history of settlement pump supports have been down gradually.
I carried out piping stress analysis based on original design conditions but stress are within allowalble as per ASME B31.3.
If so, what solution would be reviewed to prevent gradual settelement.
I wish to hear from some experienced people on this matter.

Thank you.

 

[NozzleTwister]

106coral,

First let me address your comment, "I carried out piping stress analysis based on original design conditions but stress are within allowable as per ASME B31.3." What’s more important than that is to qualify your pump nozzle loads per API 610 or the vendor's allowables. Generally, pump nozzles are overloaded long before your piping is overstressed.

You don't give much info but I assume that you are supporting your in-line pump, the suction and discharge piping each from different foundations or pedestals. Let me add that many in-line pumps do not have to be independently supported, they can be supported from the inlet and outlet piping. API 610 addresses this.

Many plants have very poor soil conditions and settlement happens. You can't stop it but you can take steps to minimize it and minimize its effect on your pump and pump piping.

I assume that your foundations are being designed by a civil engineer based on the loads and the site soil conditions, if not, they need to be. Often when settlement is a concern, I ask for the pump and piping supports to be tied to a common foundation or mat, this way the piping supports and pump settle together minimizing the impact on the pump nozzles.

Another solution, less desirable in my opinion but used by many, is to install adjustable base ells on the suction and discharge piping and periodically adjust them as settlement occurs.

Good luck,


NozzleTwister
Houston, Texas