Trenchless Renewal Methods for Replacement, Renovation of Pipelines

Construction innovations and trenchless renewal methods are continually evolving. The trenchless renewal approach aids in the replacement, rehabilitation, refurbishment, and upgradation of facilities. We see it as a form of renewal, in which an existing pipeline system is given a fresh lease on life. We refer to a process as a repair when no work is done to extend the design life of a utility system.

Selection of Trenchless Renewal Methods

The existing physical characteristics of the pipeline system play a role in the type of renewal selected to complete a certain task. Type, size, material, length of pipes or number of manholes, service connections, and bends are the conditions. Other issues are the issues that need to be addressed. It could be exfiltration or infiltration, misalignment, joint settlement, abrasion issues, or corrosion damage, among other things.Other factors include the method’s applicability, construction problems, financial considerations, and the pipe system’s durability.Different Types of Trenchless Renewal Methods in Action The following sections give a quick overview of each form of renewal:

1. Cured-in-Place Pipe

The process entails inserting a fabric tube into an existing pipeline that needs to be replaced. The insertion is accomplished with the use of water, winching, or air inversion. The cloth is resin drenched, which is a unique feature. This allows for the filling of cracks and the repair of gaps by passing through pipe flaws. The Cured in Place Pipe technology can be used for both structural and non-structural applications. The CIPP is so strong that it acts as a system that can support the entire pipeline system on its own. The CIPP uses high-corrosion-resistant impregnated polyester resin, also known as ERC fibre glass.

2. Underground Coatings and Linings (UCL)

The mortar or resin can be used to fill in the gaps in the lining or as coatings in trenchless renewal procedures by spraying. These linings and coatings would give better moisture resistance and consequently corrosion resistance in pipes where employees are not allowed. They play no part in improving structural integrity or repairing leaks or joints.Polyester, polyurethane, vinyl ester, concrete sealers, and silicone are some of the materials that can be utilised for this purpose. These are sprayed using a remote-controlled sprayer that is portable and travel-friendly.The illustration below depicts a lining procedure using the UCL method in a pipe with access for personnel. Underground linings’ characteristics

3. Sliplining (SL) Method of Trenchless Renewal

This is one of the most well-known trenchless renewal methods for rehabilitation facilities. This strategy can be utilised to aid the system’s structural stability restoration. If the system has any form of joint settling or misalignment, we don’t use this procedure. Sliplining is the process of inserting a new pipeline with a smaller diameter into an old one. A space is created between the pipelines, which is filled with grout. The procedure is quite inexpensive, and it gains a great deal of simplicity. Table shows the major characteristics of Sliplining, which include the fact that the approach does not gain more hydraulic capacity.

4. Modified Sliplining (MSL)

Pipe sections that are almost identical in size are put into the existing pipeline system. Grouting is used to fill the annular space. The MSL approach can be used in three different ways: Lining for Panels (PL)This improved Sliplining technology is mostly used for pipelines with a diameter greater than 48 inches. This method is a renewal method that entirely renews the pipeline system’s design life. The approach has the advantage of being able to take on many shapes. It can also accommodate non-circular cross sections. Fiberglass pipe fibres are the most common form of pipe fibre used.Spiral Injuries To renew the current pipe, the spiral wound method uses grout and layered composite PVC. When the ribbed texture of the PVC and the grout are combined, it creates a unique look.

5. In line Replacement (ILR)

This procedure is used to renew diameters ranging from 8 to 12 inches. This is mostly used in wastewater, storm water, and culvert utilities.The capacity problem of pipeline systems can be solved via in-line replacement methods. In the process of replacing a line, there are three stages:

a. A Pipe Has Burst The old pipe is broken using a hammer at this point. At the same moment, a new pipe is pulled and installed on the position. Pipe bursting can be done in a variety of ways. They are pneumatic in nature. Pipe bursting is a technique that involves breaking an existing pipe using a pneumatic hammer.

The second method is static pipe bursting, which involves removing the pipe using a tugging machine. When the old pipe is extremely ductile, this method is used. Unlike pneumatic bursting, this approach produces no noise. This strategy can be used everywhere where brute force is required. Hydraulic pipe bursting is the third way, in which the bursting head articulates, causing the pipe to burst. This approach is likewise devoid of noise.b. Insertion of the Pipe the method of pipe insertion is also known as the method of pipe expansion. This technique entails inserting a new pipe into an existing pipe. Clay or ductile iron pipes are commonly utilised.c. Pipe elimination Pipe eating is another name for this approach. This strategy is effective.

6. Close Fit Pipe (CFP)

This procedure decreases the diameter of the pipeline momentarily before being put into an existing pipeline. Once fully inserted, the diameter is restored, allowing for a close match with the original pipeline system.The approach is used for both structural and non-structural applications. Heat or pressure is used to bend the pipe used for lining to a smaller diameter. The close-fit pipe is available in two versions: structural and non-structural.The close fit pipe’s features are shown in. A tight fit renewal method for non-structural purposes is shown in the diagram below.

The three different types of close fitting pipes that are available are:

1. Pipe that has been deformed This pipe is folded and put into the host pipe. Close fitting pipe procedures allow for considerable diameter reductions of up to 50%. This can be folded in the factory or on the job site.

2. Die DesignIn the 1980s, the first close-fitting lining system was designed. The lining must be heated to a temperature of around 100 degrees Celsius in order to reduce its diameter. The winch is used to place the liner into the pipe. The winch force is released once it is in place, and the liner returns to its former shape. This approach is an ongoing procedure.It must be completed after it has been started. Any issues with sustaining winch force would cause the liner to sink.

3. Roll down the window Before entering the host pipe, the liner is permanently semi-reduced in diameter. To lower the diameter, a set of hemispherical rollers is used. A 10% reduction has been made. An increase in wall thickness jeopardises this long-term reduction.The liner is returned to its original dimensions by using pressurised cold water. For liners with thinner walls, this approach is less suitable. The winch loads used here are very low when compared to other methods.

7. Point Source Repair (PSR) Method

Local flaws are more likely to be discovered in structurally active pipelines. In these cases, a point source or localised repair might be appropriate. Resin can be used to seal defects with diameters ranging from 4 to 24 inches. These are sprayed using specialised machinery that are commonly available. The approach primarily encounters four issues. They are as follows: The masonry’s loose structural portion must be preserved.Local structural capacity should be provided. As a result, it will be able to support the loads while also assisting the damaged pipes.In order to prevent penetration and exfiltration, a seal must be provided.Sections of od pipe that are missing and need to be Replacements of Point Source Repair (PSR) Repairing and closing a localised source Leakage can be reduced by reducing the amount of time it takes to halt it.

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