The sifs for tee's are not calcuated by the program, you have to put them in.
For bends the max sif is 2.5 (code BS7159). Yet the sifs calculated by the program are much higher (3 to 4).
How can you erik.scheir@telenet.be solve this problem?

UKOOA “Part 3 – System Design, Paragraph 6.3.3 Stress Intensification Factors” states:

"Because of ovalisation of the cross section during bending, the stresses in a pipe elbow or tee are greater than those in a straight pipe of the same wall construction and diameter under the same bending moment. These ratios are known as stress intensification factors (SIFs).

For the determination of stress intensification factors, reference should be made to BS 7159."

1) CAESAR II does calculate the SIFs for tees, using the BS 7159 formulas. If you have an example where the SIFs were not calculated for a tee, please send the file to us and we will investigate.

2) You say that the max SIF for bends is 2.5. Did you get this limitation from UKOOA, or from BS 7159? I don’t see it in either. Please provide a reference.

See ISO 14692-3: The empirical relationships for flexibility factor, stress intensification factors, and pressure stress multipliers are based on BS 7159.
An upper limit, based on experience, is placed on Sft.It shall not be greater than 2.3.
Caesar calculates the Sifs but the upper limit is not applied and the Sifs are always>2.3.
Shoudn't you take into account the thickness of the of the branch laminate and put them in the spreadsheet of the Tee?
The factor m is the stress multiplier but when you put in a value you get an error.

1. ISO 14692 puts a limitation on the SIFs, neither BS 7159 nor UKOOA do. CAESAR II implements BS 7159 and UKOOA, not ISO 14692. Therefore CAESAR II does not implement a limitation.

2. The branch thickness is taken from the pipe thickness on the spreadsheet of the element that represents the branch.

3. I don't get an error when I enter a value for m on the spreadsheet. Can you send more information on what the error is, or send the file that causes it?

Per UKOOA the following error appears, inputting a value 1 for m in the spreadsheet for Tee's:
"Error 1E: item B1 or B2 on element # tot # is incorrectly specified or omitted".

Per ISO 14692(based on BS 7159) the pressure stress multiplier, used in system design calculations shall be set to 1.

Since it is impossible to set this value,is this value calculated by Caesar and what is the formula, or where can you find this value in the output.
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Eek!

As stated above, CAESAR II does not implement ISO14692.

The BS 7159 pressure stress multiplier for tees is defined in BS 7159 Figure 7.12.

m = 1.4 * lambda_z^0.25

You need to specify this value. I have no problem defining values for "m". If you continue to have problems, send me your model.

OK but as I said before ISO 14692 is based on the BS 7159 code and the same formula for the pressure stress multiplier is used.
An upper limit, based on expirience is placed on m such that m shall not be grater than 3.
Ameron who fabricate FRP in the Netherlands saus that can use a factor 1 for m.

What if you dont specify m? Is it taken 1 by th program?

Can you give me the e-mail adress where I can send the input file to?

techsupport@coade.com

Richard,

If UKOOA SIFs for bends is based on BS 7159 sec. 7.3.1.4, fig 7.1, why the values are different?

I did a simple model with a bend and a tee using BS 7159 and duplicate the pipeline and change the code for UKOOA.

For tees the SIFs are the same, but for bend not.

Can you help me?

Thanks in advance,

Miyamoto

Richard,

Please help me with this issue.

Regards,

Miyamoto

One item of input for BS 7159 bend SIFs is design strain. This value can be provided in the .FRP file.

UKOOA uses the BS 7159 elbow SIFs but has no matching value for design strain in that FRP file for UKOOA.

I believe yoru difference is caused by a differnce in the design strain used.

Dave,

Design strain by vendor is different of BS 7159. For UKOOA Sif calculation design strain can be only that find in stardard?

Class 1: 0.0018
Class 2: 0.0015
Class 3: 0.0012
Class 4: 0.0009

For another values of design strain, UKOOA don't use BS 7159 formulas?

Regards,

Miyamoto