Is the roller support for large bore piping in rack realistic ? How many of us have used such supports, say for hot flare piping in refinery ?

regards,
sam

mmmmmm.
Im not petrochem, but would imagine roller supports to bestsuited to situation where frequent/large movement is required or sliding supports are problematic (dirty environments?)

For outdoor piping with temperature, sliding support is difficult to maintain. Regarding frequent large thermal movement, it is difficult to postulate how frequently these could happen. The need for low friction arises from the high weight load of pipe and its content which translates into friction load on structure at anchors due to thermal expansion of piping from ambient to flexibility (design) temperature.

regards,

sam

Roller supports , in my experience are not good as over a period of time, they get jammed due to combination on environmental and lack of maintenance effects.

Regards

If I rephraze the problem replacing roller with teflon slide:

Is teflon slideplate type support for large bore OSBL piping in rack realistic ? How many of us have used such supports, say for hot flare piping in refinery ?

regards,
sam

I have been inspecting old high temperature lines. Problems recorded with teflon pads:
- slip out (possibly not properly fixed in position)
- fly ash and other dirt mess them up
- on hot pipe without some insulation break they overheat
I would use teflon only if I have to. Any extra item requiring maintenace and not really required is no go. Erection is also an issue. Basically it doesn't matter what you do sliding surfaces are not protected and they get damaged during erection.

Thank You, Jouko for discussing the problems faced with teflon pads used in supports of high temperature piping.

It is obvious that none uses teflon pads just for fun. For similar reason of special requirement of care in erection & maintenance, in offsite pipe rack people use spring hangers sparingly.

regards,

sam

My experience with them has been both good and bad... I have seen them take a cold set and stick rather than slide.... IMHO there is no fool proof roller or slide arrangement they all need some maintenance even if it is only "exercise".

Thank You Sir, for your reply.

You have rightly opined that there exists no really 'zero-maintenance' special supports like rollers or slide plates.

When people compare so less number of incidents in nuclear industry compared to process industry, other than inherently safer and detailed design, the very important role of maintenance and routine audits are not given proper credit.

regards,
sam

sam,

You mention high friction loads due to content. My experience with refinery flare systems is the content is mostly vapor and the liquid carry-over that doesn't flash is minimal. If you are releasing that much liquid into the flare header, do you also have slugging problems?

Pick any low friction device and someone has had a bad experience with it. If you can't get Structural to design for the load you may have to pick the lesser of evils for your situation.

My experience with rollers is that they don't. All of the existing rollers that I have seen in the field (refineries) have long been rusted to the point they were locked completely.

Years ago I had a conversation with an applications engineer for Fluorogold/Flourocarbon/Furon (whatever they call themselves now) in Athens, Texas. He recommended my upper plate on Teflon slide supports to be polished SS and completely covers the lower Teflon plate through all movement cycles. This keeps dirt off of the Teflon and prevents the cold set. If temperature is a problem there are Teflon slide plate assemblies that have an insulating block between your support and the Teflon.

Also graphite slide plates although fragile will handle high temperatures and I understand they tolerate dirt well.

There are also several brands of slide plates made from bronze impregnated with graphite and oil.

Like John said, all systems require maintenance but my experience with refineries is that it's probably not going to happen. I would pick what would work best with no maintenance.

Check out the non-mandatory appendix in B31.1 which discusses and recomends a hanger maintenance program.... I had an owner griping to me about his pipe supports when I asked him if he ever walked them down the response was no.... so I asked him how he could expect them to be okay after cycling, and dynamic loading, time and time again... like driving your car, never changing the oil and getting mad when the engine bites the bullet.... just ignorant!