Putting two springs in a series makes a longer spring and reduces the spring rate by a function of how much longer the overall coil is made, whereas putting them in parallel does not change the spring rate but increases the load capacity.
It is possible but not recommended. You would lose the flexibility of being able to adjust the spring support height or load capacity.
The function of a spring is to absorb movement in the pipe caused by thermal and load displacements.
In order to set (load) a spring support, you must ensure that the pipe system is at its cold (installed) state. (All hydro-testing has been completed.) At this point, with variable springs, the lower travel stops should be removed. Adjust the load at the load column of the spring so that a load slightly above the cold load is reached. The remaining travel stops can now be removed. Note: Excessive force should not be required to remove the travel stops at this time.
For variable springs there are 23 sizes with loads ranging from 50 lb. through 50,000 lb. For constant springs, there are 110 sizes with travel ranging from 1″ to 14″ and loads ranging from 0 lb. to 90,000 lb.
PTP-8 Type C Variable Spring Assemblies
Figure 100 C-Type Constant Springs
PTP 100-C Size 84 Constant
In order to remove a spring support, first you must ensure that the spring is at its designed cold (installed) position. Next, re-install the travel stop(s) in the support. Then, provide adequate temporary support for the piping system. Once you have adequate support, you can release the load from the spring. Finally, remove the spring support from the piping system.
Variable Spring Support with Travel Stops in Place
A variable spring support is a pipe support that uses a spring coil (or series of coils) to accommodate pipe movement from the initial (installed) condition to the final (operating) condition of the piping system. For all variable spring supports there must be a difference in load and that load difference will be based upon the spring rate of the coil(s) specified.
Variable Spring Supports