Dear Colleagues

Please kindly share your expert opinion on application of Variable vs. Constant Springs and low friction TSP (PTFE) plates in combination with springs:
1. What variability/vertical travel of variable spring support is generally acceptable in front of static equipment (tanks, vessels. etc) subjected to settlement or thermal expansion?
2. Is there a variability or/and vertical travel threshold when a variable spring in vicinity of equipment is not considered as a good engineering practice and application of constant spring is required to keep the nozzle load within allowable?
3. What magnitude of horizontal movement of the shoe on a spring can load flange requires using TSP to reduce a lateral force on a spring?
4. What magnitude of horizontal movement may be considered for modeling spring as frictionless in CII and what horizontal movement on a spring load flange requires modeling spring with friction to calculate true nozzle loads.
5. Does physical location of the TSP (inside or outside the building) effects/limits/requires application of TSP? Would either of these locations be a preference or otherwise not recommended for using TSP in oppose to regular CS shoe?

Thanks a lot for your time and expertise!
Vikoll

1. Typically 25% variability

2. For rotating equipment, typically 15% variability

3. Can allow 1/4" to 1/2" lateral movement at a can spring frictionlessly (per WRC 44)

4. See 3.

5. Outdoors Teflon will get dirtier and less effective than Teflon indoors.

Hi Vikoll...

Just adding on the point mentioned by Dave..If your movement exceeds 1/2" you may go for guided column type of spring design!!

Keep Smiling,

SJ

Definitely use a guided support.