The state of pipelining today
Decisions on DWV pipe rehabilitation.
Pipelining, as it is known today, is the process of reconditioning the inside of a pipeline with an internal coating or casting to extend the remaining useful life of the piping asset. Pipe coating has been utilized in pressurized pipelines for more than 60 years.
Cured-in-place pipelining technology was first implemented in Europe in 1971, and it was used to rehabilitate storm drains in an aged building to stop rainwater from leaking into the building. The process works this way: A resin-saturated fabric is pulled through an existing pipeline, and then an internal bladder or calibration tube is inflated to press the fabric against the host pipe. The fabric is left to harden and cure before the bladder is deflated and extracted from the rehabilitated new pipe inside the old pipe. It is known as insitu form, the Latin for “formed in place.” Eric Wood, the man who pioneered this technology, used the shorthand for the name of his own company, Insituform Technologies.
The first American patent for this technology was issued to Wood in 1977. It had grown into a rehabilitative technology for large diameter sanitary and storm mains, which are used to collect effluent from properties and deliver the waste to be processed to treatment plants.
Application of the new process for larger pipes had to be altered from the original pull-in-place design. Instead, a process was developed by which the resin saturated material was pulled or inverted into the pipeline via a head of water or air pressure, followed by the internal insertion of a calibration tube into the material by means of either method. The general name for this process was deemed “inversion.”
By the time the process had made it over to the U.S., many different resins and fabrics, as well as combinations thereof, were being used to perform this type of rehabilitation. Shortly after the entry into the North American market, the American Society of Testing and Material began issuing standards of practice for the utilization of cured-in-place pipelining in the rehabilitation of pipelines.
As a result, there are now standards that govern the use of this type of technology, in addition to the underlying math and science that guides the application of this technology. All these are needed to maintain the minimum requirements necessary to support conditions in the existing host pipe. These standards have been developed to take into consideration whether a pipe is fully or partially deteriorated. In turn, the grade of deterioration determines whether or not spot repair is required for portions of a piping system that are obstructed and cannot be removed by pipe cleaning tools.
These standards have specific design calculations which include strength, leakage and flexural properties that are supported by design life criteria. These also determine the type of resin/host CIPP material that should be employed in the process. This type of rehabilitation has certain benefits compared to other methods: It is safer and less destructive, requires less reconstruction post rehabilitation, it is less time consuming, and most importantly, more economical.
Today, there are technologies for almost every type of piping system — pressurized and non-pressurized, plumbing and mechanical — utilized in homes and businesses, commercial and industrial facilities and even cruise ships and navy vessels. The need to remediate piping infrastructure worldwide grows only stronger as piping systems all around continue to age and deteriorate.