Design of High Pressure Flex Coils

[HHume]

I am hunting around for the standard design equations for helical coil springs using ¼” (quarter inch) O.D. 60,0000 psi stainless steel tubing. The aim is to design flexible coils that are carrying high pressure liquid - the coils may be in extension or in torsion while conveying the high pressure liquid. Conventional spring design equations are readily available but I would like to use, for example, whatever people in the waterjet industry currently use for their high pressure flex coils (at least as a starting point). I would like to look at both extension and torsion applications. The tubing will be pressurized to about 60,000 psi and in our application will be very cold.

Could someone point me in a productive direction? Thus far I have drawn a blank although I suspect I might be able to derive something if I really have to.