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Long story short. Some idiot poured down half a gallon of mixed epoxy into the sink, and washed it down with water. Epoxy traveled quite far, and then hardened, fusing with the pipes, creating a hard and watertight clog. The clog happens to be in a place where it is completely inaccessible (under and inside structural elements), so it is impossible to replace these pipes without demolishing half of the building. What are some ways to separate that epoxy from the pipes and clear the plug? We already tried flexible "snakes", but the epoxy is fused with the pipe, and won't move. Are there any chemicals that can dissolve it or break it apart without damaging the pipes? As far as we know, the pipes in that section are made from PVC.

I know it is a hard case... But demolishing half the building is really not an option. Looking forward to your ideas!

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    Do you know what the exact kind of epoxy was? – Jon Apr 30 '18 at 23:45
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    Our 47-year-old 1-story tract house has ABS drains under a slab. Older houses in our neighborhood and some more expensive "custom" houseswere build with cast iron drains. These are now starting to fail by corroding through. In our tract neighborhood tunneling has been used on a few houses to completely replace the cast iron drains with PVC. To get to a limited break or blockage one would have to jackhammer the slab. – Jim Stewart May 1 '18 at 1:38
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    It was the 30-min epoxy, made by Voschemie, in Germany. It's a very old building, at least 40 years old, and it didn't have the standards that are required today. These pipes are under multiple slabs, and these slabs hold walls... If we start hammering, the building might come down. – J R May 1 '18 at 7:20
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    The problem is just about anything that will eat the epoxy will damage the plastic pipe. Even trying to fix a cutting attachment to a snake could cause the snake to wear through the pipe at any bends (been there done that with a large power snake). – Ed Beal Jun 29 '18 at 22:48
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    I hope the idiot has good liability insurance to pay the cost of demolishing half the building. More seriously, you can't remove the old pipes without demolishing the building, but that doesn't mean you can't add new pipes, wherever they would be put in newer construction in some more accessible place, right? Your old pipes are probably beyond help. – Glenn Willen Jun 30 '18 at 7:05
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I think you need new pipes, man.

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I would expect any chemical approach suitable for removing epoxy will also remove PVC pipe, perhaps more easily than the epoxy! My research shows that acetone and heat in combination will work, but is time consuming. Acetone also dissolves PVC pipe quite nicely, even without heat, making this inappropriate.

I found a great mechanical solution, but it's possible that your pipe size would be too small: http://www.jettyrobot.com/

jetty robot

It appears from the image that the diameter is adjustable, but without scale, it's difficult to determine how small it will collapse. The options are great, walnut blasting, dry ice blasting, sand blasting, but is it too big? I'd try the dry ice blasting, as there would be minimal residue as the CO2 sublimated, but it's also possible that dry ice isn't power enough to bust up the epoxy.

It's a long shot, but I would consider to find a top-end makerspace and ask if the members could build a use-specific (one-time, one-fit) device that would resemble the jetty robot. You could get away with the motor from a cordless drill or a corded drill and a long power and control cord. Chuck a hole saw of suitable diameter in the drill and use a long flexible stick to apply pressure.

It would be best if the last accessible point of the plumbing is cut away to remove as many bends as possible.

EDIT: DIY options.

I found this one meter long drill extender:

drill extension cable

Four or five of them would quickly become unwieldy and could twist into itself over such a length. I had envisioned a cylinder at the clog end with the last chuck centered in the cylinder, grippers engaged but I've discarded that idea as impractical. Pursuing another idea, I found hydraulic hose (which will be available in any length needed) with diameters inclusive to your pipe size.

Such a large diameter hose should be able to be pushed to the clogged area with sufficient force and perhaps some cable-pulling-lubricant to ease entry. The hose would do double duty as the means for removing any water remaining as well as serve as a delivery system for the clog removal.

I had considered to suggest an abrasive removal, but if the pipe is plastic, the abrasive could weaken the walls excessively.

The hydraulic hose, on the other hand, if sized to just fit inside the pipe could be modified at the working end to hold a cutter of some sort. In this example, one could envision a hole saw slightly smaller than the pipe inside diameter secured to the end of the hose. Water might not have to be removed if this method is used. The hole saw would have to be small enough to manage any bends in the pipe.

Electrical conduit is frequently installed with sweeps, gentle curves to allow wiring to be pulled through after installation. Water piping rarely uses such methods, as water tends to flow around minor obstacles. If there are any 90° elbows or even 135° elbows, it's possible this exercise is for naught.

It's really founded on the possibility of getting to the clog with anything that won't damage the pipe walls. Hydraulic hose is going to be a strong delivery system, but an expensive test/experiment to see if it will make it all the way.

I think the next step is to remove all the water, followed by a camera inspection, even a DIY version to image all points in the pipe to the clog location. Returning results of no elbows would be best.

EDIT: Adding critical consideration:

Epoxy is generally liquid (obviously) and has flowed into the pipe causing this clog. It is reasonable to expect that the clog is not a cleanly engineered solid plug and may have a number of "organic shape" components where it bonds to the pipe wall.

This increases the importance of having a visual for the clog. The first priority would be a camera, perhaps live, or at the least recorded and retrieved.

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  • Jetty robot seems to be too big and expensive, but maybe we can make a power drill motor on a power cord. However, how do we provide enough holding power on the motor while it runs the drill, so the motor doesn't start rotating in the opposite direction, twisting the cord and the stick? – J R May 1 '18 at 8:32
  • There are so many variables involved in this problem to complicate the answer to your question. How far to the clog from the last accessible point in the plumbing? Not from the last drain, but from where you can cut away to get the shortest distance? What diameter pipe? The jetty robot uses the tracks to provide anti-rotation, not so simple. A mechanical equivalent with cable actuation and spikes or pads instead of tracks might work. Important! Suck out all the water first. – fred_dot_u May 1 '18 at 9:44
  • We estimate that the clog is about 4.5 meters away from the last accessible point, and god knows how many bends in that distance. Pipe diameter is about 4 cm. Spikes and pads you mentioned - how would we make them engage only when needed, and disengage when we want to take the robot out? – J R May 1 '18 at 19:52
  • tiny pipe, challenging build but not impossible if there aren't too many bends. If many bends, oh golly. Motorcycle cable with housing is very strong. Bicycle cable strong too, easier to find in great lengths. Secure housing at "robot" end, with inner cable attached to pad arm/spike arm. With right geometry, pulling on user end of cable (think brake lever) causes pad arm to extend. I'm going to edit post for DIY suggestions. – fred_dot_u May 1 '18 at 20:51

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