Stress analysis of ABS pipes for chilled water application

[brkumar]

Hi,
I am representing the manufacturers of ABS pressure pipes that is being used for chilled water and condenser application (HVAC)in the ME. We have a very small market and it is a tough sell.
It is an uphill battle against the tried and tested black steel piping for the same application.
To win some projects,we need to provide a full stress analysis of the pipe work using ABS (at least for the plant room, with large bore piping- DN650 & DN750.
The temperature range is 5 to 41 deg C, with an ambient of 50 deg C max (the installation temperature for worst case expansion/contraction calculations.
We have a free lancer, who can do the modeling of ABS pipes, but needs full material data.
I have also requested the modeler to provide me the questionnaire for updating the ABS pipe material data in his Caesar ii for analysis.
Appreciate if anyone can help me as to what are all the details that is needed for correctly modeling ABS pipes in Cii, within the above temperature range, although it can be used sub-zero.
Note: I have very little knowledge on Cii, as I had completed a static stress analysis 5 day course in Chennai a few years back and have not a chance to practice it on my own.

If anyone can help me, I will first send the available data in excel format and after your inputs will then forward to my modeler, and then may be lease my own Cii software for occasional analysis for some prestigious projects.

Please help.

Regards
Kumar

 

[stanier]

Hi Kumar,
You are likely to get a lot on nonsensical replies about how you should be using DICL, dont use a free lancer for your stress analysis etc etc. I hope people keep on topic and provide sensible suggestions related to stress analysis experiences with thermoplastic pipes. I know how difficult it is to sell in the UAE and what the sub sub sub contractors expect of suppliers. It is not like the well oiled USA industry.

I would be interested to know if there are any technical papers on the creep decay of thermoplastic materials. ie Once a load is applied to a pipe system the stress dissipates in time. What is the relationship between load, temperature and stress decay for a thermoplastic material?

“The beautiful thing about learning is that no one can take it away from you.”
---B.B. King

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[brkumar]

Dear Stainer,
Thanks for the tips and I am showing below the data that we have on our ABS pressure pipes.
the UTS is 40MPa at 20 deg C.
Data at various operating temperature range for SHORT TERM OF .005 YEARS DESIGN LIFE and for LONG TERM 50 YEARS DESIGN life.


The top half the SHORT TERM data.
Operating Pressure at 20˚ C in bar ( P ):12
MRS (σLPL) for time 50 years at 20˚ C:16
Overall Service Design Coefficient ( C ):1.6
Design Stress σS = MRS / C:10
Pipe Series S = σS*10 / P:8.3333
Standard Dimension Ratio SDR = 2 S + 1 17.67
Overall Service Design Coefficient ( C ):1.6
UTS below is MRS (σLPL )based on design life.
Allowed ST below is Design Stress MPa

Design Life in Years: 0.005
UTS(MPa) Allowed ST(MPa)
Service Temperature 10˚ C 32.51 20.32
20˚ C 27.32 17.08
30˚ C 24.36 15.23
40˚ C 20.04 12.53
50˚ C 16.28 10.18
60˚ C 11.84 7.4

Design Life in Years 50

Service Temperature 10˚ C 19.41 12.13
20˚ C 16.01 10.01
30˚ C 12.82 8.01
40˚ C 9.04 5.65
50˚ C 6.99 4.37
60˚ C 3.92 2.45

Hope this helps and am eagerly waiting for some helpful advice.

Regards
Kumar