Lubricating Slide Supports
Lubricating Slide Supports
(OP)
I am working on a set of double-stacked horizontal vessels; each vessel has one fixed and one sliding base plate. The top vessels bolt to the bottom vessels as the bottom vessels are bolted to the foundations. There is a significant amount of thermal growth and during our fatigue analysis, concerns have been raised about a "slip/stick" phenomenon occuring at the steel/steel sliding interface, especially between the top and bottom vessels. We are at a point where we are looking into lubricating the slide plates. Furthermore, we are also thinking about adding grease zerks so the end user can provide lubrication throughout the life of the vessels.
Is there another way to address this problem? The end user is not interested in PTFE pads. If lubrication is the way to go, is there a certain grease I can recommend they use? Is adding grease zerks in the sliding base plates a reasonable step to take (if they actually get used 10 years from now is unknown!)?
Is there another way to address this problem? The end user is not interested in PTFE pads. If lubrication is the way to go, is there a certain grease I can recommend they use? Is adding grease zerks in the sliding base plates a reasonable step to take (if they actually get used 10 years from now is unknown!)?





RE: Lubricating Slide Supports
Bottom Vessel ----
How big is the vessel (Diameter, Length, Wall thickness. etc) ?
What is the material of the vessel?
What is the Operation Temperature of the Vessel?
What is the Operating Pressure?
What is the Commodity in the vessel?
What is the specific gravity of the commodity?
What is the total Operating Weight of the vessel?
Top Vessel -------
How big is the vessel (Diameter, Length, Wall thickness. etc) ?
What is the material of the vessel?
What is the Operation Temperature of the Vessel?
What is the Operating Pressure?
What is the Commodity in the vessel?
What is the specific gravity of the commodity?
What is the total Operating Weight of the vessel?
Support Structure ----
Are these vessels supported on simple "T" supports?
or
Are these Vessels supported in a more complex (four leg,multi-level) structure?
Other -------
Are there any direct piping connections between these two vessels?
What is the location/country of installation?
RE: Lubricating Slide Supports
The bottom vessel has a full encirclement "wear pad" and "T" supports on top and bottom. The "T" support on the top vessel rests on the top support of the bottom vessel.
The vessels are to be installed in the U.S. and the piping to each vessel runs from a separate manifold system.
The support/foundation design is complete. We are just trying to find a way to ensure this possible slip/stick sliding condidtion is never realized. Grease seems to be a simple solution. Thanks.
RE: Lubricating Slide Supports
http://www.hipertech.com/spip/pdf/AFG2EN.pdf
or
Google for others
RE: Lubricating Slide Supports
For this application the grease alone won't be enough, the asperities on the contact surfaces will in time lock together due to extruding of the grease and you'll be left with full contact of carbon steel plates. Typically, a polished thin plate (could be stainless steel) is inserted between the top and bottom suport/base plates, including lots of grease;- you might want to consider side guides on the bottom vessel support plates, in order to minimse the bolting torque down to finger tight (on the sliding side only!)
cheers,
gr2vessels
RE: Lubricating Slide Supports
The weight transfer is then straight up and down, with no real moment loads to be passed from the top vessel to the bottom vessel. The weight of the top vessel can be carried by (non-pressure bearing) simple structural legs coming up from the lower vessel, and extending down to the concrete. Rolling distance for an 85 foot tank is 2 - 4 inches at the legs, so the plates need to be slightly longer than that, which is easy to plan for.
Greasing the rollers, and preventing rust from freezing movement, is simpler than trying to maintain a "perfect" greased surface between two large plates.
RE: Lubricating Slide Supports
I would have thought a pukka ptfe or self lubricating metal bearing would be the only option.
RE: Lubricating Slide Supports
RE: Lubricating Slide Supports
boilerone, I am not entirely sure. We suggested PTFE and I think there was some concern about having to possibly replace them after x number of years. We may be able to present some of our fatigue data and steer them back down that road. Any opinions about a PTFE pad vs. a thin SS plate?
Thank you all,
RTS
RE: Lubricating Slide Supports
Why are these plates good enough for bridges/boilers etc etc....but not good enough for your client..???
http://www.sepbearings.com/fluorogold.pdf
There are structural/pipe support applications that were designed in the 1970s and earlier that are in great shape.
(Note: I have always been an strong advocate of mandatory drug testing for clients and thier reps)
-MJC
RE: Lubricating Slide Supports
If they don't like these, then you will have to reinvent the wheel. MJCronin's response is apropos.
RE: Lubricating Slide Supports
pveng6224
RE: Lubricating Slide Supports
We had another system were we used a similar design using Cast Iron instead of bronze. If I recall correctly the sliding plates were CS running against the CI.
Here are some wear plates with lubrication grooves. They also have graphite groves and plugs.
http://ww