Reformer Piping Stress Analysis

"STRESS OF LARGE DIAMETER PIPING SYSTEM SHOE SUPPORT"
Proceedings of the ASME 2017 Pressure Vessels & Piping Division Conference, PVP2017, July 16-20, 2017, Waikoloa, Hawaii, United States.

FIG.1 TYPICAL SHOE SUPPORT

FIG.2 SYMMETRY AND MESHED FINITE ELEMENT
MODEL

TOTAL STRESS INTENSITY FOR D/T=200, WRAP
ANGLE 120°, AND b/D=0.5 SHOE SUPPORT

STRESS INTENSITY OF ELASTIC-PLASTIC
ANALYSIS RESULT FOR LOCAL FAILURE EVALUATION

EQUIVALENT PLASTIC STRAIN PLUS COLD
FORMING STRAIN OF ELASTIC-PLASTIC ANALYSIS
RESULT FOR LOCAL FAILURE EVALUATION

LIMITING TRIAXIAL STRAIN FOR ELASTICPLASTIC
ANALYSIS RESULT FOR LOCAL FAILURE
EVALUATION

ASME-B31J-2008-Test Method for Determining Stress Intensification Factor

PVP2015-45378"Stress Intensification Factor for Large Diameter Welding Tee Connections"
Proceedings of the ASME 2015 Pressure Vessels and Piping Conference, July 19-23, 2015, Boston, Massachusetts

Static Method of Wind Analysis of Piping systems in Caesar II using Pressure Vs elevation Method

Wind load is an occasional load which normally occurs less than 20% of plant operating time. There are two methods for wind analysis-Static and Dynamic.

Criteria for selection of lines for Wind Analysis:
Criteria should be mentioned in ITB document. As a guideline the following can be followed after verification from client:
• Lines with outside diameter 16” and larger (including insulation) running on 10 m and above.
• Steam / Flare header on the pipe rack.
• Other lines considered important as per stress engineer’s decision.
However if lines are covered by some shelter or other structures then wind analysis can be ignored for those lines.

Data Required for Wind Analysis:
For wind analysis you must have following data from the client.
• Wind shape factor: Normally for pipe elements the data varies from 0.6-0.8. Check in ITB what value it says to use.
• Pressure Vs Elevation Profile: Sometimes client provides this profile directly and sometimes provides equation and data to calculate the profile. A typical wind profile will be shown in diagram while explaining the steps required while analyzing using Caesar II.
• Elevation of the line under analysis. If HPP elevation is other than 0 you have to reduce HPP from line global elevation to get actual elevation.

What to check:
As per code B 31.3 we have to check code compliance of the calculated stress (Sustained +Wind). The allowable stress for wind analysis is 1.33 times Sh values. However sometimes client requires to check the nozzle loading in Operating+ Wind cases (W+T+P+Win) for static equipment. Normally client does not require wind load checking for rotating equipment.

Steps for Static Analysis in Caesar II:
Most of the steps are mentioned in attached images.
• Model the piping system under analysis from piping isometric drawings.
• Enter elevation of the first node in global coordinates.
• Click on Wind/Wave check box on Caesar II Spreadsheet and mention wind shape factor as shown in Fig. 1

Fig.1: Caesar Spreadsheet for Wind Analysis

• Now run the analysis and go to the load case editor and select Pressure Vs Elevation as shown in Fig. 2