Cured-in-place pipe
As one of the most widely used rehabilitation methods, CIPP has applications in sewer, water, gas, chemical and district heating pipelines ranging in diameter from 0.1 to 2.8 meters (2–110 inches).
A resin impregnated felt tube made of polyester, fiberglass cloth, spread tow carbon fiber or other resin-impregnable substance, is inserted or pulled through a damaged pipe, usually from an upstream access point such as a manhole or excavation.
Cured-in-place pipes require that their resin be cured after installation to achieve full strength, by hot water or steam or, if a fiberglass tube is used, by UV light.
[2] CIPP requires bypassing the existing pipeline while the liner is being installed, which may be inconvenient as, depending on diameter and system used (steam, water or UV), curing may take from one to 30 hours and must be carefully monitored, inspected, and tested.
Since ground and ambient installation conditions as well as crew skills can affect the success or failure of a cure cycle, testing is performed by 3rd party laboratories in normal cases and should be requested by the owner.
A technical presentation[3] at the CERIU INFRA 2012 Infrastructures Municipales Conference in Montreal outlined the results of a research project which examined the effects of test specimen preparation on measured flexural properties.
Research has shown that flexural testing results from the same liner material are usually lower when determined using EN ISO 11296-4 as compared to ASTM F1216.
Testing conducted by the Virginia Department of Transportation[4] and university researchers[5] from 2011 to 2013 showed that some CIPP installations can cause aquatic toxicity.
[11] In April 2018, a study funded by six state transportation agencies (1) compiled and reviewed CIPP-related surface water contamination incidents from publicly reported data; (2) analyzed CIPP water quality impacts; (3) evaluated current construction practices for CIPP installations as reported by US state transportation agencies; and (4) reviewed current standards, textbooks, and guideline documents.
[12][13] In 2019, another study funded by these agencies identified actions to reduce chemical release from ultraviolet light (UV) CIPP manufacturing sites.
On July 26, 2017, Purdue University researchers published a peer-reviewed study in the American Chemical Society's journal Environmental Science & Technology Letters about material emissions collected and analyzed from steam cured CIPP installations in Indiana and California.
[16] On August 25, 2017, the National Association of Sewer Service Companies, Incorporated (NASSCO), which is a (501c6) nonprofit dedicated to "improving the success rate of everyone involved in the pipeline rehabilitation industry through education, technical resources, and industry advocacy", posted a document on its website[17] bringing up several important concerns and unanswered questions regarding the study, and its messaging.
Later in September, the NASSCO posted a request for proposals to “review of recent publication(s) that propose the presence of organic chemicals and other available literature relating to emissions associated with the CIPP installation process, and a scope of services for additional sampling and analysis of emissions during the field installation of CIPP using the steam cure process.” The request specifically identified the project would review studies conducted by the Virginia Department of Transportation, California Department of Transportation, and Purdue University.
At the federal and state levels in September 2017, on September 26, the US Centers for Disease Control and Prevention (CDC) National Institute for Occupational Safety and Health (NIOSH) published a Science Blog contribution regarding Inhalation and Dermal Exposure Risks Associated with Sanitary Sewer, Storm Sewer, and Drinking Water Pipe Repairs.
[30] Later that year, a study in the Journal of Cleaner Production revealed that by modifying the initiator loading, an ingredient in thermal based CIPP resins, pollution potential of the process could be reduced by 33-42%.
[31] In October, researchers discovered that steam based CIPP creates and emits nanoplastics into the air during plastic manufacture.
