GNFC CASE STUDY
Performed Computer Aided Piping Stress & Flexibility Analysis work for inlet and outlet lines of energy conservation turbine.
The formidable aspects of the projects were,
- High Operating Parameters of 90 bar g Pressure and 480°C Temperature.
- Co-relating the axis of the turbine and Caesar-II model while performing the analysis.
- Rerouting the piping with variable springs and appropriate restraints yielded favorable results on Turbine nozzles.
- Verifying the forces/moments acting on the turbine nozzles (in Sustained, operating temperature and design temperature case) using Limit 1 and Limit 2 equations, which inherently refers to NEMA SM 23 equations with 2 times of NEMA SM 23 allowable, where forces and moments were resolved at the center line of Turbine shaft and Biggest nozzle (Turbine Exhaust).
- Maintaining the natural frequency of the system while keeping it outside of resonance range of turbine frequency.
LYB BELLOW CASE STUDY
Performed pipe stress analysis of existing 54" emergency flare header which is inlet to emergency flare KO drum and 54" existing flare outlet header which is outlet of flare KO drum and going to emergency flare stack due to replacement of 3 expansion joint.
The reason for replacement of existing joint was those 54” expansion joint were originally installed in 1975, hence it was recommended to replace them to maintain a reliable operation and to avoid a potential incident associated with expansion joint failure.
When the As built model were analyzed with the expansion bellow as per the existing bellow data sheet (Single Tied Bellow, Lateral movement-0mm, Angular rotation-2).
The stresses due to expansion, occasional conditions in the piping system were found exceeding the limits prescribed by ASME code B31.3.
Hence, it was concluded that Existing Bellow shall be replaced with the new bellow with reduced stiffness value.
When the recommended case had been analyzed with the "suggested" stiffness as per US-Bellow Catalogue.
The stresses due to sustain, expansion, occasional conditions in the piping system were within the prescribed limit of ASME code B31.3. The nozzle loads on vessel were found within the allowable limit. However, nozzle loads were also submitted to Static Engineer for further verification.
Also, Expansion Joint Datasheet were prepared and submitted to the Bellow Vendor for approval and verification of the stiffness.
Natural frequency had also been checked by Modal Analysis and observed to be above 4Hz which is an acceptable value
42” FEED GAS PIPELINE FLEXIBILITY ANALYSIS
PIPELINE SEISMIC ANALYSIS FOR FAULT CROSSING AT SUKAL RIVER CHAINAGE 169.152 km
- The calculations has been Performed for the Seismic Buried fault analysis for 18” steel pipeline with the methods outlined in IITK-GSDMA Guidelines for Seismic Design of Buried Pipelines, November 2007 & Stress analysis has been performed considering soil stiffness considering 1 km stretch on the either side of pipeline as per code ASME B 31.4 using Beam element software CAESAR- II with High operating parameters of 98 bar g & 45 °C Temperature.
- The result shows that portion of the pipeline to the extent of 1km on either side from the fault crossings can sustain the load without casing pipe until the depth of cover as indicated in the alignment sheets. The location of the seismic fault crossings has been referred from the alignment sheets & the crossing drawings.
- The results are analyzed for the allowable strain in tension and compression for PGD, Buoyancy due to liquefaction, Fault crossing and Seismic wave propagation as per IITK-GSDMA guideline.
- The list of other calculations performed is as follows:
- Operating strain in pipe .
- Soil Liquefaction: Buoyancy and Permanent Ground Deformation (PGD) calculations
- Seismic Wave Propagation
- Strain Due To Fault Crossing
- Soil spring stiffness calculations
- Stress analysis considering Seismic accelerations
- Upheaval Buckling
- The results of the calculations, in accordance with IITK-GSDMA guidelines, November 2007, show that the pipeline stretch under analysis can sustain the possible fault movement due to seismic event without any additional changes in the present route and design.
- STRESS ANALYSIS OF JACKETED PIPING (CLEAN FULES PROJECT)
Performed the Stress analysis of Jacketed & Non- Jacketed piping having 10 numbers of critical systems with 43 numbers of jacketed lines & 13 numbers of Non - Jacketed lines.
The formidable aspects of project were,
- High operating parameters of 14 bar g & 190 °C Temperature of Jacket & 3.6 bar g & 170 °C Temperature of Core.
- To model core and jacket in CAESAR II.
- Analysis the systems considering boundary conditions
- To qualify flanges in flange leakage check.
- SIF calculations for CROSS as per FEA
- Nozzle Pro/ API 650 Nozzle Flexibility/FEA
- Internal Pressure Check for Core and Jacket: As per ASME B31.3
- External Pressure Check for core, as per Sec VIII Part D
- Trimming length calculations
- Equivalent fluid density inside jacket
- Expansion stress check at junctions
- Buckling load Check.
- Welding Adequacy Check
- Deflection check of Jacket
- Tank Bulging calculation