Few days back I had published a post on Methods for checking flange leakage.
In that article the I had mentioned the theoritical background (analysis criteria, basic theory behind flange leakage checking, analysis methodology etc) for checking flange leakage. So click here
to refer the article once again before you proceed on this article. In this current write up I will explain the step by step method for performing flange leakage analysis methodology following Pressure Equvalent Method using Caesar II. Click here to check the ASME Section VIII method.
Fig. 1: Typical flange in Caesar II model
Caesar II methodology for Pressure Equivalent method:
- Model the stress system from stress isometric. After modelling is complete select the flange which need checking as per pressure equivalent method. In Fig. 1, node 20-30 and node 30-40 denotes the flange assembly. And flange leakage checking is required for node 30.
- Now select the Flange Node(From/To/Both) and Calculation Type as shown in Fig. 2.
- Select Flange Class/Grade through ‘Read from File’ button and refer to ASME B 16.5/ ASME B 16.47 material tables.
- Required data will automatically be filled. By default the value of G will be taken as the mean gasket diameter. User to update the value of G as per ASME B 16.20 & ASME Sec. VIII Div. 1, Appendix 2, Table 2-5-2. based on following equation:
- b0 = 1/4, G = Mean diameter of the gasket contact face
- b0 > 1/4, G = Outside diameter of gasket contact face less 2b, b=basic gasket width from code. check the above mentioned link for details.
Fig. 2: Caesar II Spread sheet typical input
- Now go to the load case editor and select the temperature at which flange leakage checking to be performed as shown in Fig. 3. Now run the analysis to check the results. In case the generated stress exceeds the allowable results will be shown in red colour. Check Fig. 4 for output results.
Fig. 3: Load Case Options module in Caesar II
Fig. 4: Caesar II flange leakage pressure equivalent output