LEAKAGE TEST OF WATER PIPELINE

Leakage Testing of Pressurized Water Pipelines: A Case Study on a 1200 mm Diameter Ductile Iron Pipeline

In pressurized water pipeline systems, leakage testing is a critical procedure to ensure the integrity, safety, and long-term performance of the infrastructure. Any undetected leakage within the system can lead to significant water loss, structural damage, and potential service disruptions. Therefore, conducting a proper leakage test is not only a technical requirement but also an essential quality assurance measure.

Leakage testing is typically carried out by applying internal pressure to a defined section of the pipeline. Each segment is tested individually to verify its performance under specified pressure conditions. Once all individual segments meet the acceptable criteria, a final test is conducted for the entire pipeline system to confirm its overall integrity.

This article focuses on the leakage testing procedure for a one-kilometer-long ductile iron (DI) pipeline with a diameter of 1200 mm.

Testing Procedure

To perform an effective leakage test, a systematic approach must be followed. The key steps are outlined below:

1. Isolation of the Test Section

The pipeline segment to be tested must first be securely isolated. This is achieved by installing end covers at both ends of the pipe section. These end covers should be positioned concentrically to ensure uniform contact along the entire circumference of the pipe. Mechanical joints are typically used to secure the end covers, providing the necessary strength and sealing capability to withstand the test pressure.

     

  In the pictures workers are installing an end cap and jointing it with nuts and bolts ensuring no gasket failure. This operation should be done on both side of the segment.

2. Providing Structural Support at the Cap

Ensuring proper support at the cap is a critical step in maintaining structural stability during construction. The process begins with the placement of heavy precast concrete sections in position. Once these elements are installed, the gap between the precast section and the sheet pile must be carefully filled with cast-in-place concrete to achieve full contact and load transfer.

To enhance the support system, H-beams in combination with a 150-ton hydraulic jack can be utilized, depending on the magnitude of the applied pressure. This arrangement helps in effectively resisting the imposed loads and maintaining alignment.

It is essential to ensure that no gaps remain at any joint during the installation of the beams and jacks. Even minor discontinuities can lead to displacement when the pipeline is subjected to pressure, potentially compromising the integrity of the system.

As illustrated in the image, workers are in the process of installing the precast slab and providing the necessary support. This procedure should be consistently applied on both sides of the segment to ensure uniform stability and performance.

3. Leakage Testing Setup and Instrumentation Procedure

The leakage testing setup is carried out in a systematic and controlled manner to ensure accuracy and safety. Initially, a GI pipe is securely connected to the end cap, which is already equipped with provisions for pipe connection and a gate valve. Following this, essential instruments such as a flow meter and a pressure gauge are installed onto the GI pipe to enable proper monitoring during the test.

All joints and connections must be carefully inspected during installation to ensure they are fully sealed and free from leakage. A pressure pump is then connected to the system, allowing the required internal pressure to be generated within the pipeline for testing purposes.

During the water filling process inside the DI pipe, any air valves present within the test section must be kept open to allow trapped air to escape, ensuring accurate pressure readings and preventing air pockets from affecting the test results.

The accompanying images demonstrate the correct procedure for connecting the GI pipe and associated components, providing a clear visual reference for conducting an effective leakage test.

Once the pipeline has been completely filled with water, internal pressure should be gradually increased using a calibrated pressure pump in accordance with the specified test requirements. During the pressurization phase, it is essential to continuously monitor all exposed joints, connections, and fittings to ensure their integrity. Any sign of weakness or failure at this stage may lead to significant damage or safety hazards.

Strict safety protocols must be enforced throughout the testing process. Unauthorized personnel must not be permitted within the working area, as sudden failures under pressure can pose serious risks.

The procedure outlined above represents one commonly adopted method for leakage testing. Alternative testing approaches may also be applicable depending on project specifications and site conditions. Constructive input or recommendations regarding other effective testing methods would be highly appreciated.