Surge & Transient Analysis

Surge & Transient Analysis

Pipelines are used for the transportation of fluids, either liquid or gas. The flow direction in the pipeline is controlled with fittings such as Pressure Control valves, Flow Control Valves, Level Control Valves, Normal isolation valves, elbow, reducer, expander, drain valves, Tee- joint, etc. The majority of pipelines taking (Tie-in) from Brown Field Projects are not straight pipelines. The Process Engineer will be taking care of the process parameters through a hydraulic calculation study.

Sometimes the flow can vary due to sudden changes abruptly in process conditions in the dynamic stage of the plant.?When the flow through the pipeline is suddenly stopped due to any emergency or operational reasons, the sudden change of momentum increases or decreases the pressure very quickly. The impact of such a sudden increase or decrease in pressure is quite significant and can severely affect the operation and safety of the entire pipeline. Therefore, Surge analysis has become critical for designing and maintaining the pipeline to avoid any catastrophic failure.

DEPCS uses Honeywell Unisim Simulation for the entire pipeline, including the pumps and valves. During the analysis, the characteristics of the pipeline are collected from the client. The inputs for performing the surge analysis are:

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• Characteristics of the pipeline
• Type of fluid
• Type of pumps, valves, and fittings
• Inlet Stream data (Composition, Mass flow, Temperature & Pressure details)
• Valve datasheets
• Tank datasheets
• Pump datasheet and operating curve
• Operation philosophy for this facility
• Site conditions (Ambient pressure & temperature details)
• Piping material specification
• Battery limit conditions
• Piping GAD or Isometrics
• Report templates if any to be followed
• Other relevant data required for the project.

DEPCS Surge team will do the surge analysis (indicate the Hammer effects) in the pipeline in different Scenarios. Our team will also recommend valve closure time, Maximum flow rate, or surge capacity.

The simulation is performed by manipulating the parameters, like changing the flow rate, tripping off the control valves, operating conditions, closure of valves, etc., and studying its effect on the pipeline. Recommending Pilot-operated surge relief valves that are typically used to protect pipelines that move low-viscosity products like gasoline or diesel.

This style of valve is installed downstream of the pump/valve that creates the surge. The valve is controlled by an external, normally closed pilot valve.

Surge pressure, or “water hammer,” is a short-term pressure increase due to a fluid velocity change in a pipeline.

Hydraulic transients, or pressure surges, are created when sudden changes in flow rates occur in pumping and pipeline systems. The pressures created may be high enough to damage or even cause catastrophic failure of pipelines.

DEPCS Surge & Transient Analysis team completely runs the simulation on UniSim Simulation. Our team is currently working on projects such as Surge & Transient Analysis for the pipelines in the Tank farm area – Medina Airport Project and Surge & Transient Analysis for the Underground Gas pipeline for Oman Refinery.