Dear Coade Members

Hi all..Iam doing stress analysis for RTRP Pipe (filament wound) of sizes 12”, 20” & 24” with corresponding design pressures of 14.4 barg, 17.8 barg, & 25 barg. Iam using BS7159 standard for the same. Vendor proposed the values for the RTRP and im enclosing it for your ready reference.

In the Caesar configuration set up file I have used Axial modulus of elasticity, Axial strain : hoop stress for 21 deg C.viz, Axial modulus of elasticity as 10000 N/mm2 and Axial strain : hoop stress as 0.16 (calculated for 21 deg.C). I have taken the Caesar default value for ratio of shear mod : elastic mod as 0.64 from Caesar.FRP file.

Also I was informed from my senior engineer to consider the value of allowable stress as 100MPa for RTRP material as I found there is no specific calculation for allowable stress in BS7159. Kindly advise whether Iam proceeding correctly with all the values. Your early response will be very much helpful for me.

I have repeatedly recommended on this forum that all stress analysis for RTRP pipe should be performed by the vendor.

He can give you properties data, but

1. What SIF's are appropriate for fittings?

2. How should you model joints in long straight runs?

3. How should you take into account the collapse strength due to external loads (if buried)?

4. What happens to the pipe at support points because of the deformation created by the pipe supports (if aobve ground)?

5. Is the CAESAR II default value of shear mod/elastic mod valid for this product from this vendor?

6. What tolerances apply to his properties data? (B31 properties are "specified minimum", I'll bet he gave you "average" properties.)

If you do this analysis without resolving all these issues, YOU are taking responsibility for the design. Do you want to do that?

For FRP / RTRP , i advise to use the UKOOA and ISO 14692 as a study code instead of BS7159 . Because BS7159 is considered an old code for FRP system .

Agreed with your statement, indeed vendor should be more familiar with their own materials. by reply to your query , here have some recommendations.

1. Normally RTRP pipe vendors will consider the default SIF value by taking UKOOA & ISO14692 as the study code.

2. what kind of joint you refering ? I deem is fitting ( elbow, tee) , so it will refer to vendor (PDT)product dimension table and model as exact with the PDT.E.g , when a long run pipe come to a fitting , the thickness of the fitting is increased (refer to PDT) then in modelling we shall increase the thcikness similar as in PDT.

3. Collapse streght ? for U/G piping system will not consider the this usually .I am not so sure

4. The support span vendor in RTRP system, normally vendor will follow the standard UKOOA,ISO14692 while similar case in steel pipe will follow ASME B31.3

5.Indeed the default value is not valid in RTRP pipe , well users shall provide their table according to the standard as well . Users can refer to standard code UKOOA , Part 3 to find the answer.

6.Tolenrances this not sure , cause vendor normally will not consider it in their analysis. I not sure weather steel pipe has consider this or not .

Hope this will help you

Regard

Glenn

Dear Members,

For RTRP piping the type of connection we use in our project is a mechanical joint connection. In our case we have tee connection and I am in a doubt to choose the type of connection in CAESAR modeling (i.e.) tapered or welding or others etc. Also I don’t find any Tee joint connection for plastic piping such as mechanical joint, spigot or socket joint etc in CAESAR. I request the Coade member to provide the solution regarding what type of connection shall be used for tee fittings.

This also depends on the method used to manufacture the tee. If you check ISO14692 (OR BS7159) you can see that they give two different ways to calculate the SIF factor, respectively for moulded and fabricated tees. The wall thickness used in the calculation is different and CII can't really handle the fabricated version. If you have a fabricated tee you must add the SIF yourself or enter half of the reinforced wall thickness. The last option will give you a more flexible tee though.

CAESAR II will not address ISO-14692 "joints" until Version 5.20.

What I tried to say is that ISO14692 uses the same SIFS as BS7159. But I just checked and it is only half true. They say they've based the SIFS on those from BS7159, but they only give the moulded versions for the calculations.

BTW: When is V5.2 finished? I applied for a beta version too, but never heard anything about it.

We are targeting late January for the release of Version 5.20.

All "Beta requests" were submitted to "COADE Sales" for verification (i.e. current, full run users). Those who could not be so qualified were contacted to rectify the situation.

Send me an e-mail with your ESL number and company name and I'll check on your status.