Code of Practice for Machine Wound Spiral Lining Suiting Technique Suiting Indian Conditions

Table of Contents

PREFACE

Water and sewage infrastructure and other utility services represent a significant investment on the part of most urban local bodies. For well over 100 years, the distribution networks for utility services have been located underground in pipes or ducts that are laid, repaired or replaced by trenching from the surface. In cities and urban areas, these distribution networks are located underneath roads. This often makes access difficult, particularly in areas congested with traffic and buildings. When pipeline infrastructure is not well maintained, inefficiencies occur. For example, in water distribution systems, this can lead to leakage and possible water shortages. In sewage systems, cracked and damaged pipes can cause wastewater seepage, leading to contamination of groundwater and in extreme conditions can lead to even road cave-ins. These problems often give rise to related health and environmental issues that were avoidable if the rehabilitation is done at an appropriate time.

Perhaps the largest share of the trenchless market is represented by the requirement to rehabilitate defective pipelines with some residual structural and physical life, which can be used as a structure for the new line. Examples of rehabilitation techniques include Machine Wound Spiral Lining (MSWL), Cured-in-Place Lining (CIPP), Close-Fit Lining, Slip-lining, and Spray Lining, all with their own-patented variations, as well as various other localised repair techniques. Variations relate to the material used, wall thickness provided to offset structural or physical defects, the rate of rehabilitation, status of fluid flow, and the minimum time of shut-down for the existing service.

Machine Wound Spiral Lining process provides an efficient method for rehabilitating defective gravity flow pipelines like sewers, culverts, and other similar type of pipes. In the process, a profiled PVC or HDPE strip is spirally wound by a winding machine to create the continuous liner pipe from within the existing manhole or insertion pit/location or within the defective pipeline. The liner section, thus created, is installed in the defective portion of the pipeline due to the progression leading to creation of a leak proof barrier and prevention of leakage from such locations. For buried pipelines this process is quite effective as the liner is inserted in the host pipe with limited disruption of services as it does not involve in-situ curing as for some other techniques for existing buried pipelines on a long term.

The liner formation could be done, either by positioning the winding machine in the manhole/insertion pit and inserting the liner section in the defective portion of the pipeline due to rotational action of the winding arm of the machine, or by creating the liner section wile traversing the winding machine in the host pipe. Dimensions of such liner pipe are adjusted to match closely with the host pipe. The annulus created between the outer liner surface & internal host pipe surface requires to be grouted for stabilizing the liner in position and make it composite with the host pipe. The liner created is formed in a way that the internal pipe surface is smooth whereas the external surface is ribbed to provide strength to the profile that generally is thin walled.

This technique can be used for pipe size ranging from 150 mm to 3000mm ID. Working methodology and installed materials are to be selected on the basis of project requirements. The need therefore is to standardize the operations so that the liner created performs as per the designed outcomes and such standardization suiting Indian conditions is being done through this Code of Practice for Spirally Wound Pipe Lining Technique suiting Indian Conditions that we are pleased to present here. Itis developed to assist the project owners and the service providers in attaining the desired outcome of the rehabilitation process. Specifications proposed are aimed to help in developing the pipeline with desired properties and strengths if followed properly. Stipulated specifications have been developed with the assistance of the working committee members and are the first attempt at standardizing the technique so that procurement process could be more transparent and the product could be economic in the long run. As with all codes of practices, this would be reviewed and updated with times and the user/reader is invited to send their comments for a further development of the code.

Dr. Niranjan Swarup
Director General
Indian Society for Trenchless Technology