Spring on Rollers?
Spring on Rollers?
(OP)
Well, now I've seen everything. As of this posting, this bit is currently featured on the home page at PTP
http://www.pipingtech.com/

PT&P custom designed and fabricated these F-type variable springs with rollers to be used in a refinery in Kansas. The variables are fabricated from carbon steel with a stainless steel clamp-on shoe that attaches to the load column. These F-type variable spring assemblies measure 23" in height and have an upward travel of 3". The operating load is 1,000 lb. and the installed load is 1,300 lb. The function of this custom designed variable spring is to allow large axial movement along the axis of the pipe centerline. The load column is modified to accommodate the special clamp-on shoe. The customized wheels allow for movement of the entire spring assembly in conjuction with the pipe.
http://www.pipingtech.com/

PT&P custom designed and fabricated these F-type variable springs with rollers to be used in a refinery in Kansas. The variables are fabricated from carbon steel with a stainless steel clamp-on shoe that attaches to the load column. These F-type variable spring assemblies measure 23" in height and have an upward travel of 3". The operating load is 1,000 lb. and the installed load is 1,300 lb. The function of this custom designed variable spring is to allow large axial movement along the axis of the pipe centerline. The load column is modified to accommodate the special clamp-on shoe. The customized wheels allow for movement of the entire spring assembly in conjuction with the pipe.
Edward L. Klein
Pipe Stress Engineer
Houston, Texas
"All the world is a Spring"
All opinions expressed here are my own and not my company's.





RE: Spring on Rollers?
If you're getting that much motion, why not put an expansion loop?
RE: Spring on Rollers?
RE: Spring on Rollers?
Edward L. Klein
Pipe Stress Engineer
Houston, Texas
"All the world is a Spring"
All opinions expressed here are my own and not my company's.
RE: Spring on Rollers?
RE: Spring on Rollers?
http://virtualpipeline.spaces.msn.com
"We can't solve problems by using the same kind of thinking we used when we created them." -Albert Einstein
RE: Spring on Rollers?
They may well work fine in Caesar but you and I know that because Caesar results show things work does not mean that the actual physical implementation can be performed. You know things like "modelling" very small "gaps" and the like which provide acceptable results but cannot be constructed. Unfortunately there are a number of Stress Engineers who "model" things in Caesar which cannot physically be installed just to get the results they want.
RE: Spring on Rollers?
I do some training on pipe stress. First thing I teach is that CII is nothing more than a really fast calculator and that it is REALLY good at GIGO.
There are all sorts of exmaples out there of items or systems that work great on paper but that can't be built. That's why you have senior-level design seminars in school: to hopefully get some exposure to what works in the real world, and what doesn't.
These are weird times in the oil patch, no?
RE: Spring on Rollers?
RE: Spring on Rollers?
These nice open bearings and axles, however, solve all those problems!
I've got another failure mode for these things: Something ends up on the ground and chocks one of the casters. Anyone who's ever wheeled around a garage on a crawler knows that a small wheel comes equipped with a poorly understood fifth fundamental force of nature that attracts objects just barely over the critical height at which they will chock a wheel.
RE: Spring on Rollers?
Regards,
XHPIPE
RE: Spring on Rollers?
Hopefully, this will be an eye opener to our up and coming stress folks that they need to ask the question "How are we going to do that" once they get that seemingly perfect arrangement of X, Y, and Z restraints in their model.
Edward L. Klein
Pipe Stress Engineer
Houston, Texas
"All the world is a Spring"
All opinions expressed here are my own and not my company's.
RE: Spring on Rollers?
Rube Goldburg LIVES!!!!!!!!!!!!!!!!!!!!
RE: Spring on Rollers?
Actually I know of a power plant in Texas that has a Main Steam Piping system constant hanger attached to an overhead structure that rides on four three inch ball bearings within a "box" that limits its horizontal travel. The maintenance folks have been feeding the ball bearings white lithium disulfide grease on a regular basis for (so they say) thirty years. Inventive but of course not very practical - the ball bearings have worn-in a "track" now so those now define the real travel limit.
Then again that is Power Piping, B31.1 still includes the "........all pipe supporting elements SHALL be in accordance with the rules of MSS SP-58...." (paraphrased) and B31.3 simply references MSS SP-58 for figures that illustrate some types of acceptable supports/hangers.
Thanks to Ed for making Monday morning more interesting
Regards, John
RE: Spring on Rollers?
The garage creeper analogy was what first came to my mind. They roll whichever direction the wheels are pointed.
RE: Spring on Rollers?
Yep, the olde Grinnell figure 170 is actually included in MSS SP-58. And yes, the same Texas power plant has some of those supporting the NPS 3 MS start-up steam to the BFW pump piping. However that plant is a natural gas fired (clean) plant. But they get almost as much "travel" due to hanger "swing" as they do from the rollers.
Regards, John.
RE: Spring on Rollers?
Hee hee. THIS, plus the subject photo, is exactly why one of my standard interview questions for potential engineering hires is "Do you work on your own car?" You wouldn't believe the looks and the replies I get... My experience is that a guy who knwos how to turn a wrench is pretty durn good in the design office as well... They don't turn out designs like Ed's picture