Stress Analysis and Support Design for Pipelines
Objective: The objective of this analysis is to check the pipelines of various industries for operating & occasional loads. The piping network are then designed, that can withstand these loads & forces. Purpose of analysis is to determine the stresses, deflection & forces in pipelines in design as well as operating condition. Based on analysis results, various design modifications like flexible connectors, rigid anchors, additional supports, spring hangers are suggested.
Stress analysis is conducted to come up with innovative design solutions that meet international code compliances like IBC, UBC, BS, ASME, FEMA, API 618 and API 674. Design of structural steel supports for various piping systems are designed using FEM. These supports are designed using BS 5950 & ASCE.
Modeling & Analysis: The 3D modeling for the entire pipeline network with all the bends and runs along with initial support locations are captured and modeled using pipe stress analysis software Bentley-AutoPIPE.
The piping system are appropriately modeled accounting for their loss coefficient and elevation.
The analysis shows the displacement for the pipes at different locations and also the stresses caused due to operating & occasional loads. Various combinations of loading on the pipeline are provided as per applicable standards, which includes:
i) Dead load
ii) Pressure Load
iii) Thermal Load,
iv) Seismic loads.
Outputs: The output results are compared with allowable values of pipe material and if stresses or deflection exceeds allowable limits, suitable design modification are suggested to mitigate stresses. The results are presented in pictorially and tabular format in a report showing. :-
The stress ratio for the different load combinations.
Design modifications like additional supports & their types, if required in piping network, to reduce the stresses.
Marked AutoCAD drawings with support locations & additional supports and other design modifications, if required.
Forces & Moments acting on each support in all 3 directions.
Stress Isometrics for Piping network.
Structural steel support for Piping system to sustain various loads.
Minor details like base plate calculation, anchor bolt calculation & weld calculation are included in report for different types of supports.
Surge Analysis
The objective of the Surge analysis is to ensure that the pressures in the piping network are within the acceptable criteria for most severe cases of surge scenarios. The acceptable criteria for a study are as below:
Maximum Pressure: The max pressure in the pipeline at any time and at any point in the network shall always be less than the rated pressure of the pipeline.
Minimum Pressure:
Discharge Side: The pressure inside the entire pipeline on the discharge side of the pump house shall not become negative at any point of time during any transient event. Thus the pressure on the discharge side should always be above 0 Bar.
Suction Side: At the suction side of the pump, cavitation’s shall not happen otherwise it will harm the pump and pipeline.
Some of the common cases of Surge analysis are: Pump Shutdown & Pump Start-up event.
Modeling & Analysis: The pipeline has generic pipeline components like valves, area change, expansion joints, elbows, tee junction etc. The information of the component locations are determined from the given AutoCAD drawings. These drawings were used to create piping layout in the model for the surge analysis software.
The components are appropriately modeled accounting for their loss coefficient and elevation. Pump data, pipe properties along with boundary conditions such as pressure drop and various other components like fittings, valves, bends, elbows, tees, inlets, expansion and contraction are modeled as junction with elevation and pipes.
Outputs: The Graphs during Pump Shutdown & Pump Start-up showing;
Pressure contours in complete network
Comparison of Pressure inside the pipeline with Vapour Pressure
Graphs near to Pump to show Pressure gradient / peak during shut down and start-up condition.
Hydraulic grade and Air/Vapor volume near to pump discharge/suction side.
