Large-diameter sewer and drain lines can benefit from pipe lining technologies
Pipe lining is an inside job…
Most plumbers have at least basic familiarity with epoxy lining a building’s potable water system as an alternative to a repipe with a whole new plumbing system. The strategy is simple enough – uncap and dry out the lines, blast through an abrasive like aluminum oxide powder to get rid of the crust and corrosion and to give the inside of the pipe some “tooth” so the epoxy blend blown into the system in the next step will have something to grab onto.
Pipe lining is basically a method for bringing new life to old, corroded pipes, mitigating internal corrosion and collapsed pipes. Or, as Tom Bowman, domestic and international license manager for Nu Flow Technologies said, it’s an infrastructure fix.
“We prefer to call it a repair for renewing aged infrastructure,” Bowman said. “That might be infrastructure of all sorts. Where it has primarily been used is the sewer industry for sanitary sewer drains.”
There are basically two types of cured-in-place pipe lining that can be used in large diameter pipes in the sewer and drain environment, Bowman said. One method is aptly called, “inversion.” The other is called pull-in-place. For inversion, imagine an epoxy-lined sock or New Year’s noisemaker that gets blown inside the pipe. For pull-in-place, picture a tube that’s literally pulled into place inside the pipeline.
“Inversion primarily came about for large tube or large diameter pipelining. I mean large, I’m talking about municipal style systems, 48-inch and above, very large distribution type sanitary mains. Over the years, that translated to small diameter as well, meaning eight- or 10-inch and below.”
“Access will be made to the piping system via a manhole or potentially a large ditch, not necessarily a large ditch but an access point directly onto the sewer,” Bowman said, noting it’s possible to start an inversion tube without having a large access point, however, it’s not widely used because the success rate is not fantastic.
After using vacuum to saturate the fabric liner with the epoxy material, installers will use an apparatus to roll up the material into a drum and affix the closed end of the liner to a connection point on that mechanical device: “Then they’ll apply either air pressure or water pressure to the, at that time, what is the outside of that liner thus putting pressure on that,” Bowman said. “Again, the front side is held tight on to the inverting drum or the inverter mechanism, and that force inverts the material putting pressure and pushing that liner all the way down through and into the host pipe for renewal. It’s like rolling up a sock and pulling it on over your foot. “
The end result is a clean, clear pipe with any minor cracks repaired and ready to put back into service – a brand-new pipe, in effect, without having to excavate and replace: “These processes are formally governed by pretty much all of the same governing bodies that normal plumbing materials are governed by. The ASTM rating for cured-in-place pipelining will fall under ASTM 1216, and its appendixes, as well as ASTM 1743. It means NSF 14, which is the National Sanitation Foundation’s certification for plastic drainage. Some products on the marketplace conform to the current as well as past years’ IPCs, UPCs, IRCs, ICCs.”
The second type of pipe lining for larger diameter pipes is called pull-in place. It’s also used in main sewer lines, although it’s not as frequent because it’s easier to use inversion when there’s direct access, Bowman said. “We can make allowances for connections and Ys and Ts that are in the system. That said, we can line the lateral all day, every day without having to build a big or an access point on to the host pipe. And what we do is we will utilize existing means of accessing the plumbing network via a water closet collar or a clean-out or a vent line, whatever it might be. And what we’ll do is we will string a pull rope or a pull cable from that access point to a downstream access point, which could be a downstream branch or a clean-out. It could be a downstream manhole. And what’s nice about the pull-in-place is it allows us the ability to start and stop anywhere in the middle of the system.”
Because there’s no need to start the repair directly where the system is entered, and because there is a pull cable on both ends of the system, techs are able to manipulate the repair sleeve – an epoxy-impregnated felt tube — both forward or backward thus being able to become very accurate with the repair installation.
Bowman said installers have a lot more control with pull-in-place in the smaller diameter pipes than with inversion and the large diameter pipes.
“Not to say that guys who are really, really, really skilled with their trade of utilizing the inversion method can’t sometimes line two- and three-inch pipes using that method. It’s just not done all that often. For that application, it’s probably not the most appropriate application of technology.”
With these two methods, inversion and pull-in-place, you’ve got everything covered from two-inch all the way up to 72-inch pipes. And when you do them, you have in effect whole new pipe or new section of pipe. Is pipelining a remedial type of job or is it something that, say, someone on the commercial side will do to a new plumbing system to give it extra life or to make sure there aren’t going to be any failures, or to just be a “belt and suspenders” kind of guy?
“It is becoming more rampant that it is used in primarily old systems. However, it is also used on new installs. Matter of fact, I just watched a product being done by a licensee where they were taking out old pipe, replacing new cast iron pipe based on the fact that the building is over three stories tall. And they were pre-lining that pipe prior to installing it, so as to protect it from future corrosion,” Bowman said. “And this particular installation was in a parking garage of a very upscale condominium complex where you have Porsches and Lamborghinis and Jaguars and Maseratis sitting underneath it. And they were tired of the old system which was only just under 10 years old, which was failing cast iron and leaking rusty, excuse the phrase, well, poop water, onto their very expensive $100,000+ cars.”
The most important thing for a contractor to take away from a discussion of lining large diameter sewer and drain lines is the processes save both time and money.
“Understanding the differences of technology and what the appropriate application for the technology is probably the most important takeaway,” Bowman said. “Understanding the differences between the inversion method and the pull-in-place method, especially when it comes to small diameter, is good knowledge to have.”