Surge Analysis is fundamental to efficient and safe pipelines as surges in pipelines are the leading cause of inefficiency, failures, and unwanted phenomenon such as pipeline raptures, valve damage, hammering, cavitation, resonance, etc.

Surge Analysis can assist in analyzing and identifying potential surges circumstances in pipelines and help design pipelines and their components that would experience no minimum surge events.

This article will give you an adequate insight into the surges, the problems caused by them, and the Importance of surge analysis in pipeline design and safety.

What Is Surge?

Pipelines are interconnected pipes and systems or components such as pumps, valves, and other controlling devices used to transport to lengths various types of fluids, such as liquids, gasses, and other substances.

When moving inside pipelines, fluids possess kinetic energy by their motion and velocity. Sometimes, there is a sudden velocity change because of unforeseen reasons.

As a result, the kinetic energy transiently causes a sudden change in pressure, also known as Surge in pipelines.

Surge: Why Does It Occur and What Are Its Impact? 

The potential reasons causing sudden changes in the pressure of fluids inside pipelines are as follows:

1. Valve Operations

Sudden closure and opening of valves cause sudden decrease and increase in fluid pressure leading to a surge in pipelines and problems, such as rapture in pipes, valve damages, pump failure, etc.

2. Pump Shutdown

Immediate pump shutdowns due to power cuts, breakdowns, etc., cause rapid stoppage of fluid supply and, in turn, rapid decrease in pressure or surge and fluid surging back to the pump leading to pump damage and pipe rapture, etc.

3. Complex Geometry

Complex geometries of pipelines, such as sudden changes in dimension, direction, and elevation of pipes, result in pipeline fluctuation or surge. This could lead to hammering, cavitation, rapture, and damage.

4. Compressibility of fluid 

Compressibility of fluids is the measure of change in fluid volume under pressure. The higher compressibility of fluids (gases and some liquids like hydrocarbons), the more they cause surges in pipelines due to changes in fluid flow.

5. Supply Fluctuation

Sudden requirements for change in supply can also cause a surge in pipelines as the pipeline experience immediate less or more pressure exertion leading to pipe rapture, valve damage, pump failure, etc.

Now that we have understood surges in pipelines and the extent of problems caused by them, let’s explore surge analysis as a solution and its importance.

Surge Analysis: Its Importance in Pipeline Design and Safety

Surge analysis is carried out to study the transient change in pressure or surge in pipelines. It allows experts to identify the potential surge occurrence.

In addition, the analysis also traces their effects on pipelines to optimize pipeline design and their components, namely, valves, pumps, etc., to ensure safe and efficient operations of pipelines.

Surge analysis is of paramount importance for efficient and safe pipeline design. Here is why:

1. Prediction of Surge Events

Surge analysis enables engineers to identify potential surge occurrences in pipelines by simulating the hydraulic behavior of pipelines under different conditions to understand pipelines’ capacity to bear surge events.

To evaluate the hydraulic behavior of pipelines, the analysis takes into consideration the facts that influence the surge in pipelines, such as-

• valve operations

• pumps’ characteristics

• requirements of supply of fluid, etc.

2. Precise Identification of Probable Surge Events

In addition, surge analysis can determine surge events by analyzing the pipelines’ behavior under different conditions of valve operations, such as sudden closures of valves.

Consequently, it helps to identify the critical valve closure time closure rates that may cause a surge.

3. Identifying Intra-pipe Pressure Drops

Surge analysis can identify potential surges caused by pumps’ trips. When pumps stop abruptly, supplies are suddenly stopped, and pressure drops immediately, resulting in a surge.

4. Design and Sizing of Systems

The design and sizing of systems or components determine the safety and efficiency of pipelines. During the designing phase, surface analysis can help design and size appropriate pumps, valves, and pipelines to ensure that they can withstand the expected surges and flow.

The analysis can also evaluate installed devices’ performance to minimize surges’ effects on pipelines, namely, surge relief valves, surge tanks, air valves, etc.

These devices play a crucial role in mitigating surge effects, and surge analysis can determine the proper size and location of these devices in pipelines to ensure they do their task efficiently.

5. Providing Safe Operation  

Surge analysis can ensure the safe operations of pipelines by simulating and analyzing fluid behavior in pipelines during fluctuations and analyzing different operating conditions, such as pump speed, to determine the best operating condition for pipelines. It leads to determining safe operation and increased efficiency.

Surge Analysis: Methods for Conducting 

Surge analysis uses various methods depending on the requirements and pipelines.
One of the most prominent methods is the numerical method. It involves solving problems using numerical models in computer programs( CFD, Computational Fluid Dynamic) to simulate and analyze pipelines, their components, and factors that affect surge to predict surge events.

Besides that, there are three different methods in the numerical models:

1. Method of Characteristics (MOC)

Surge analysis using the MOC includes solving Partial Differential Equation (PDE) by applying wavefront of moving fluid in pipelines.

It is used to simulate those pipelines that experience a surge by the sudden change in flow rate that is mostly caused by the immediate closure of valves.

2. Finite Difference Method (FDM)

The Finite Difference Method (FDM) simulates pipelines operating under a steady-flow condition. It involves disintegrating pipelines in a small number of cells, also known as grids, and solving equations that influence fluid flows at each point.

3. Finite Element Method (FEM)

FEM includes dividing pipelines into phases and solving equations concerning fluid flow at each phase. It is used for pipelines that have a complex design.

These methods are used in computer programs, and many computer programs are used for surge analysis, namely, AFT Impulse, Pipe Surgeon, etc.

Conclusion

All in all, surge analysis is a valuable technique used to simulate pipelines to identify potential surge occurrences to optimize pipelines and their components and design measures to mitigate surge effects on pipelines and improve overall efficiency and safety.

With being significant for pipelines, surge analysis calls for expertise and experience to accomplish the task and acquire optimal results.

Mechartes is the leading simulation expert renowned for accurate results for top-notch clients worldwide. We provide various FEA and CFD simulation solutions for various industries, such as oil, gas, power, construction, HVAC, etc., including surge analysis of pipelines.

Talk to our experts to learn more!