Thermal Expansion

[rshook]

I have a 2" pipe line 36" long running at 1500 psig and 300 degrees F, fixed between a pump and a tank. The thermal expansion has placed to much stress on the pipe line. I am having trouble finding an expansion joint to handle the pressure, temperature and material (Hastelloy C-276). I have very limited room so an expansion loop doesn't look like a feasible solution. Does anyone have any suggestions.

 

[saxon]

rshook, Have you looked into moving either the pump or tank in order to fit in an expansion loop?

saxon

 

[prex]

This pipe is not very long: are you sure that the deformation of the tank wall cannot absorb the thermal expansion?
Is it possible for you to make the tank sliding on its supports? Of course this should be a small and light tank for this solution to work. prex

http://www.xcalcs.com

Online tools for structural design

 

[nrp12345]

rshook,
The thermal expansion is <1.5mm. The expansion loop reqd is small. Can you consider reorienting the tank nozzle or routing the line from another nozzle?

 

[TBP]

rshook - what is happening with this assembly? Are you sure the problem is caused by expansion? It's a very short line, doesn't get all that hot, and assuming that nrp12345's calculated expansion is correct, I'm trying to imagine field pipe work accurate to within a mm anyway.

 

[StressGuy]

I would also find it surprising that a run that short is truly overstressed. I would definitely go with prex an investigate flexibility of the tank nozzle.

Also, is the issue pipe stress or pump nozzle loading?

For an application like this, as far as a joint goes, something like this would typically be used

http://www.ethylenecorp.com/expansion_bellows.htm

You might want to look into that, although I don't know if they will handle a 1500psig design pressure. Is this pump discharging into the tank, or is it really a 1500psig suction line???? Edward L. Klein
Pipe Stress Engineer
Houston, Texas

All opinions expressed here are my own and not my company's.

 

[rshook]

Thank you for all of your help. I believe this needs a little more information from me. Yes thermal expansion is small, though axial stress seems to be high. The system is on a very small skid 48&quot; x 192&quot; x 76&quot; tall. The skid has no room available around this 2&quot; sch40 hastelloy line. The tank is pressurized to 1500psig and the pump performs as circulation only (adding approx. 200psig to the closed loop). The tank and pump are each about 1000#'s. This system is very expensive due to the hastelloy requirements and exotic fixes would not be preferred. I look forward to further advise. Thanks.

 

[davefitz]

Can you mount the pump or tank on compressible washers/ bellville springs to relief the expansion stresses? Also, the nozzle could be reinforced , full penet welds if that is the location of max stress raiser.

 

[saxon]

rshook, What about the use of Hi-pressure reinforced corrugated metal (or some type of hi temp polymer) hose ass'y?

saxon

 

[LSThill]

Hi rshook (Mechanical)

You may want to look at two application the Engineering tool's for the Job is FE-PIPE & BOS FLUIDS

http://www.paulin.com/newprg/

Leonard@thill.biz

http://www.thill.biz

 

[nrp12345]

Dear rshook,
Here is a fix which I have succesfully used in the past in our organisation.
Presumably the line is insulated.
Suggest you heat the pipe upto a temp of 300deg then make up the pump end connection, align the pump etc.
You may need to provide more insulation than necessary to reduce heat losses.
If the line is for intermittent operation suggest you install tracing, preferable electrical to maintain the temp.
Think this is feasible?
Regards
nrp12345