Line stop support in High pressure high temperature steam pipe
Line stop support in High pressure high temperature steam pipe
(OP)
Hi everybody,
I've asked some questions regarding steam turbine nozzle strengths and your replies were very useful.
I now have to design a line stop for a SA335-P22 8" NPS that runs 65 barg steam at 530ºC.
Some engineers around say that a we can't use a guide (IPN type welded to the pipe) due to stress concentration. I however believe that if we can build an IPN type guide with maximum displacements stops (in the appropriate material for high T) the line stop can be used.
What do you think?
Thanks in advance
I've asked some questions regarding steam turbine nozzle strengths and your replies were very useful.
I now have to design a line stop for a SA335-P22 8" NPS that runs 65 barg steam at 530ºC.
Some engineers around say that a we can't use a guide (IPN type welded to the pipe) due to stress concentration. I however believe that if we can build an IPN type guide with maximum displacements stops (in the appropriate material for high T) the line stop can be used.
What do you think?
Thanks in advance





RE: Line stop support in High pressure high temperature steam pipe
**********************
"The problem isn't finding the solution, its trying to get to the real question." BigInch
http://virtualpipeline.spaces.live.com/
RE: Line stop support in High pressure high temperature steam pipe
BTW there must be, perhaps a couple of engineers that have worked with this steam conditions in Uruguay and for sure they never used FEA to work them out.
And they aren't the ones around me.
In Vino Veritas
RE: Line stop support in High pressure high temperature steam pipe
You also may want to look at the Cryo guides and stops as they use a lot of bolted on products.
http://www.pipingtech.com/index.htm
RE: Line stop support in High pressure high temperature steam pipe
**********************
"The problem isn't finding the solution, its trying to get to the real question." BigInch
http://virtualpipeline.spaces.live.com/
RE: Line stop support in High pressure high temperature steam pipe
"SA335-P22 8" NPS that runs 65 barg steam at 530ºC."
Not the kind of system for a novice to be learning & discovering piping design.
Hope that you have Schedule 80 or thicker piping....
What wall thickness do you have ?
-MJC
RE: Line stop support in High pressure high temperature steam pipe
I have selected a Sch. 120 and the many (more than 1000) runs with autopipe confirm that the pipe complies with B31.1, if the supports are well fabricated.
The only messy point is that the stresses on the turbine nozzle are over (less than 50%) the ones that the manufacturer has informed.
I had accomplished the stresses before, but due to civil construction i had to modify the layout and the stresses went up again. At this point i don't really care anymore since this pipe has been around well over 12 months.
I know it's unethical to do this, but nobody else cares about the pipe flexibility and turbine nozzle stresses rather than me. It's like if i'm surrounded by insane people. And i'm really tired of looking for solutions running in circles, with no good ideas coming from anyone else.
In Vino Veritas
RE: Line stop support in High pressure high temperature steam pipe
**********************
"The problem isn't finding the solution, its trying to get to the real question." BigInch
http://virtualpipeline.spaces.live.com/
RE: Line stop support in High pressure high temperature steam pipe
thanks
RE: Line stop support in High pressure high temperature steam pipe
In Vino Veritas
RE: Line stop support in High pressure high temperature steam pipe
This is very common application, however increasing the height of the key will increase the thermal gradient, and thermal stresses. So you need to use the required height (check the thickness of the riser clamp plate) only to keep it minimum. I have not seen anyone doing any FEA and fatigue analysis on this application, it is well proven common application. But I would like to hear if there is an available proof analysis for this application.
Hope it helps.
Ibrahim Demir
RE: Line stop support in High pressure high temperature steam pipe
RE: Line stop support in High pressure high temperature steam pipe
In case you want to stop lateral movement of the pipe you still can use plate welded onto the pipe, facing a structural member, but you need to reduce the thermal gradient and thermal stresses by introducing thermal barriers . If you do not know what you are doing it can be very risky application.
If the loads are very large, I guess you should not stop the pipe moving sideway. Common approach is not to use weld integral supports onto the pipe to eliminate/reduce all the local thermal/mechanical stresses.
Ibrahim Demir
RE: Line stop support in High pressure high temperature steam pipe
http://www
thanks
Sameer
RE: Line stop support in High pressure high temperature steam pipe
In Vino Veritas
RE: Line stop support in High pressure high temperature steam pipe
Surely all of your pipework does not run axially to the flange - you must have legs perpendicular to the nozzle orientation where you can apply cold-pull to lower loads!!!
RE: Line stop support in High pressure high temperature steam pipe
- Steve Perry
RE: Line stop support in High pressure high temperature steam pipe
I suggest you to review the pipe route and supports all together.
Ibrahim Demir