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Rest Support
3

Rest Support

Rest Support

(OP)
Dear Sirs,

Do u know reason of using Rod under some rest supports? Please see attachment.

Best Regards,

RE: Rest Support

To improve longitudal movement, I guess,
Looks quite senseless to me.

RE: Rest Support

Years ago one of the major Owner/Operators (Exxon, I think) had this as their Standard to reduce the amount of corrosion at the underside of the pipe where it was in contact with the pipe support.

prognosis: Lead or Lag

RE: Rest Support

pennpiper got it.

Unfortunately it didn't work, so it was discontinued.

The detail, in fact the whole drawing, is still circulating in India and some other ME countries. I just got through deleting those exact details a couple of months ago from a new pipe support standard dwg. In fact it was stuff from the same drawing you have there.

Independent events are seldomly independent.

RE: Rest Support

Yes, ICI used to adopt this detail to try and minimise corrosion and some thought friction effects (wrongly so), however they laterly started to replace the bars with flat bar (40mm wide). The problem with the bar is you have a line load (if below a shoe) or a point load (if below a wear plate or even worse a bare pipe). If the load is reasonably high you get indentation of the pipe/wear plate which invariably increases the friction which must then be overcome before the pipe moves.

RE: Rest Support

There are epoxy 1/2-rods that are being offered now in place of the steel rod.

Independent events are seldomly independent.

RE: Rest Support

Big, do You know how they attach the epoxy to steel?

RE: Rest Support

(OP)
Thanks friends

RE: Rest Support

My initial guess had less to do with corrosion and more to do with an attempt to make a cheap rolling support, presumably in the hopes that the coefficient of rolling friction was lower than the coefficient of sliding friction. I wonder how often the bar rolls off the beam flange and is lost anyway?

RE: Rest Support

If you do like the pipeline codes say and use full encirclement supports, never.

Independent events are seldomly independent.

RE: Rest Support

I didn't look at this as a detail for pipelines; more for plant piping. the vision I have in my mind is one of a pipe that is mounted on a shoe or wear plate that, in turn, is intended to roll over top of the bar that oriented perpendicular to the pipe axis. Presumably, the structural steel is also oriented perpendicular to the pipe axis, so the axis of the bar is parallel with that of the beam. If all of that is true, then unless something stops the bar from rolling more than, say for the sake of argument, 3 inches on a 6" wide beam, the bar falls off the steel and you just end up with either unsupported pipe or a sliding steel-on-steel support anyway.

Maybe I am reading the detail wrong...

RE: Rest Support

The round bar (sometimes just half a round bar) was welded to the center of the top surface of the Structural Pipe Support Beam. The bar did not move.

prognosis: Lead or Lag

RE: Rest Support

Oh! by the way the "Bar" was the Structural Department's responsibility. That is why it is shown dotted and there with no weld symbol shown.

prognosis: Lead or Lag

RE: Rest Support

In which case it would have "worked" pretty much as I described.

I don't buy the corrosion / erosion mitigation concept in the detail as drawn. (The pipe shoe is likely the same material as the structural steel. The wear plate, maybe not. It depends on whther or not the Code and the local jurisdiction allow for welding structural grade steel to the pressure boundary.) That might have been someone's idea the first time the detail was seen by anyone in any application, but as drawn, inadvertently or otherwise, it is an attempt at a low cost rolling support.

RE: Rest Support

So who was the communist that designed this?

On the transportation side, we've been epoxying FRP spacer pads to all our pipe in the area it rests on the pipe support (EZ Line). This helps the operations group out in the regular USDOT inspection process - they no longer have to lower the support off the pipe and inspect underneath the pipe for any potential corrosion now.

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