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Controlled flash to steam? ( tickling the dragon's balls?)
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How about prewarming the sewer line for ~1/2 day, so can use sub 212 deg water to expand the new plastic line.
Danger with 250 deg comes from your taking the tubing close to failure to get it to plastic flow and expand. If it has a weak spot or old pipe has a step in it, the plastic might neck down and burst. Now you have to plan a way to safely control all that expanding steam, and direct it to where it will not cause damage.
More interesting question is what is the current sewer failure, joint leaks, rust, crushed clay, crushed tar tube, congregated plastic .... And will it contain ~30 psi ? Also what is min soil depth above it? I used sand bags when proof testing smaller then door knob sized pressure vessels to ~ 9,000 psi, to contain any shrapnel.
I've used a ~ 50k btu propane ice melting torch on low to heat PVC pipe to ~ spaghetti consistency to bend conduit around bolders and large roots when buring conduit wiring. I let flame touch pipe but always kept it moving, so pipe did not even get brown. Seemed to take at least a minute to cool by itself to become firm. After I put it in shaped I wanted it I had to wipe it with a wet rag to get it to cool quickly and set so I wouldn't have to hold it forever. But that's not practical for your application.0 -
@Leonard:
"How about prewarming the sewer line for ~1/2 day, so can use sub 212 deg water to expand the new plastic line."
What I'm observing is that the PVC is a pretty darn good insulator! (very low conductor of heat). When I get up to state change temperature "inside" the pipe for bending and expanding, the "outside" of the pipe is around 10 degrees lower temperature! (excluding any external heat robbing of its surrounding environment .... just the pipe itself!) Hence, I have to bully my heat up inside to overwhelm this pipe wall reluctance to heat up to forming temperatures.
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If can get the old sewer line warmed up , it'll reduce the cooling effect on outside of the new pvc pipe. So won't have as much a temp drop from inside to outside of new pipe. And might be able to use sub 212 forming temps for new pipe. Avoids steam danger.
I'm thinking ~ 200 deg water circulating in old pipe for few hours should warm it up a lot. After expanding, just have to keep new pipe presurized till everything coasts down in temp, maybe overnight, maybe a day.
Interestingly enough I have similar problem. Roots coming in cast iron sewer at joints about 30 and 40 ft out from house, straight sewer line to street. Have to roto-router it every 2-3 years, bunch of tall pine trees in front yard. I used utility pole steel guy wire, opened strands into a claw, and used slow powerfull 3/4 inch drill to spin it. Ran cable thru nested steel conduit as telescoping bearings to stop cable wiping, 2 people, each holding a conduit. Stay clear of the cable, seen it grab a rag and rip it, likly will do same if catches skin0 -
@Leonard:
"Danger with 250 deg comes from your taking the tubing close to failure to get it to plastic flow and expand."
Tests made at the US Army's Aberdeen Proving Grounds showed expansion factors out to 150%. This expanding of the diameter of the standard rigid PVC pipe is transformed to MOPVC (Molecular oriented PVC) and the RCP (rapid crack propagation) is lost. "hoop strength is also increased dramatically as well.
....... pipe failure (burst, cracking, etc) in this state may actually be way less than rigid PVC!
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Dupont has a PVC master batch additive that reduces the forming temperatures by 10 degrees! It also increases the "hugging" to the host pipe much better.
I hope that in adjusting the master batch "mix" of the "Elvaloy" additive, I may be able to drop forming temperatures another 5 degrees .... forming at 212 F. Hopefully I could then stay out of harm's way! : )0 -
So, I have a wrinkle for you.
PVC (with our without the Chlorination) has a coefficient of linear expansion that is 1.1" per 100 foot per 10 degrees F temperature differential.
So, I have 80' from my house to the city main in the street. 240 max temp, minus 40 degree F ground temperature is 200 degree F differential, 200 divided by 10 equals 20, so .80 X 1.1 X 20 = 17.6" of contraction as pipe cools down. If you connect the pipe to other pipes on either ends of this elongated hot inflated CPVC ballon, what happens to the 17"s of contraction that IS going to occur?
Even if you don't connect it to a pipe on one end, what happens to the existing pipe when the internal pipe contracts that 17"s?
As for no digging, how will you get the Jim cap off of the end of the pipe?
Curious minds want to know.
Interesting concept for sure, but I think you have some bugs to work out and some certification hurdles to clear with the code authorities.
METhere was an error rendering this rich post.
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One other question I have is how you would deal with couplings or other fittings? It’s been my experience that the pipe will expand but couplings will not.0
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He probably leaves excess hanging out on copper side. Won’t the cap pop off with pressure after cooling? The walls will be supported by old pipe/ground. All the stress is on cap and fill side.0
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@Mark Eatherton:
" .... what happens to the 17"s of contraction that IS going to occur?"
It doesn't "contract" ...... the expanded pipe liner is held under pressure to its new dimensions as the heated water is cooled back down to ambient. Dupont has the required temperature and pressure "profiling" needed graphed out on their website.
The new dimensions remain, as we are molecularly changing the PVC to MOPVC.0 -
@Mark Eatherton:
"...As for no digging, how will you get the Jim cap off of the end of the pipe?"
...... the thing and the end of the capped pipe cuts the cap off after all is done. (driven by a power snake)
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@L Thiesen:
" .... One other question I have is how you would deal with couplings or other fittings? It’s been my experience that the pipe will expand but couplings will not."
Your right! .... that would neck down the liner when expanding.
Answer: Don't use couplers! ..... spin weld the sections. (joint is stronger than the pipe itself!!) Expands right with the liner no problem!
(the joint is between the two black arrows!)
I have two PVC extruder co's that can "coil" the normally straight lengths of pipe as it is extruded! This would eliminate the "in-shop" spin-welding step all together. The entire extruder master batch would run continuously coiling the rigid PVC while still hot out of the extruder ...... NO joints! one continuous coiled length of pipe of any length desired ..... upto around 10,000ft! : )0 -
@ the_donut
" ....Won’t the cap pop off with pressure after cooling?"
NO! ..... I designed the process connections with a special ceramic insulator coating "this insulation is "inside the pipe!" Protects the all critical process connectors from this high heat.0 -
Hello, Propylene glycol boils at about 370F and is considered to be low in toxicity. Rather than risking steam, might it make sense to use PG? Controlling pressure and temperature would be pretty straightforward.
Yours, Larry0 -
....... how does one man get 100ft of 2" heated PVC 6 ft vertically down a 4" pipe , around a terrible bend (Trap) then extended out almost 100 ft horizontally?
That thing pictured above the host pipe is a 3" double helix spring gear box driven trap snake. The liner is feed into the center of this 3" spinning snake thats the length of the trap. Once engaged with liner pulls the entire liner into place for you!.0 -
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@Larry Weingarten:
Biological Properties
According to the MSDS, propylene glycol is slightly toxic to the skin and eyes and is toxic in large doses if ingested. Of some concern is that the compound is absorbed through the skin, meaning that large surface exposures result in symptoms similar to those produced through ingestion. In particular, propylene glycol causes damage to the central nervous system, which includes the brain and spinal cord. There is also animal evidence that it has mutagenic properties, meaning it can lead to cancer, and that it is a teratogen, meaning it causes birth defects. While large dose inhalation is rare due to the low volatility of propylene glycol, if heated and inhaled it can cause respiratory irritation and central nervous system disruption.
...... I think the plumbing inspector would get upset with me if my liner leaks 100 gals of this down the sewer. : (0 -
..... food safe thermal fluids (oil) would be great ..... but cost around $1,500 for 55 gal drum! : (
.... I could recover this fluid on each job, but this easily doubles the end user cost! I think I can safely "manage" the flash danger as I'm at the lowest end of the T&P scales.0 -
How do you get 100 ft of continuous length of "rigid" PVC to jobsite?
This is "rigid" (non-flexible) PVC heated into a "coil"
Actual jobsite coil will be 5 ft diameter with around 4 to 5 turns for a 100 ft liner.0 -
@JamiHall:
"What you will get is traveling sound waves (they really are, technically, sound waves) bouncing around inside the pressure vessel, with localized boiling at the low points and explosive collapse of the steam at the high points."
..... is this what your referring to?
https://www.youtube.com/watch?v=SR9Mq3MmDu8
Steam bubble mixing with liquid water .... then collapsing0 -
Propylene glycol is not all that toxic. It is likely you ingested some today. https://www.foodinsight.org/questions-answers-propylene-glycolRickDelta said:@Larry Weingarten:
Biological Properties
According to the MSDS, propylene glycol is slightly toxic to the skin and eyes and is toxic in large doses if ingested. Of some concern is that the compound is absorbed through the skin, meaning that large surface exposures result in symptoms similar to those produced through ingestion. In particular, propylene glycol causes damage to the central nervous system, which includes the brain and spinal cord. There is also animal evidence that it has mutagenic properties, meaning it can lead to cancer, and that it is a teratogen, meaning it causes birth defects. While large dose inhalation is rare due to the low volatility of propylene glycol, if heated and inhaled it can cause respiratory irritation and central nervous system disruption.
...... I think the plumbing inspector would get upset with me if my liner leaks 100 gals of this down the sewer. : (
It sounds like you believe this is a better option than epoxy because it can go though a trap? I have never actually seen a whole house trap but cannot imagine it is easier to work a hot liquid filled chunk of PVC through it."If you can't explain it simply, you don't understand it well enough"
Albert Einstein0 -
Well, having absolutely zero experience with MO PVC, I will have to defer to your judgement. Good luck in your ventures. One of these days, I hope to be able to say "I remember when this guy came onto The Wall, and showed us his technology. I presume you've patented everything.
Best of luck.
METhere was an error rendering this rich post.
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Just from the title of the thread you know this is dangerous and shouldn't be done. To much can go worng that is outside of your control. But if you are confident that you can see hairline fractures/ imperfections in the PVC and know that the pipe will be sturdy enough to withstand being dragged across a root or split pipe, I still say be careful.
Flash steam will melt the balls off a Dragon0 -
Off topic for this thread, but I have a lead P trap under an upstairs bathtub that needs replacing, and the tail of it was custom bent to fit in the available space between there and the stack. PVC doesn't seem to be available in the right size/angle of fittings to replace this, and I don't want bits of pipe hanging out of the kitchen ceiling. Could this be a viable way of making a new P trap out of PVC, or should I try and get someone to bend me one out of copper? Can you even use copper for a drain line?Leonard said:I've used a ~ 50k btu propane ice melting torch on low to heat PVC pipe to ~ spaghetti consistency to bend conduit around bolders and large roots when buring conduit wiring. I let flame touch pipe but always kept it moving, so pipe did not even get brown.
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@Zman:
Heating fluid costs:
Propylene glycol = $1,450 for 100 gallons
Water from jobsite garden hose = FREE! : )
https://www.kellerheartt.com/collections/55-gallon-drums-all-brands-product-lines/products/truegard-propylene-glycol-kosher-55-gallon-drum
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Shalom......I was running 2 inch white PVC plumbing pipe underground as a conduit for 1/2 inch dia wire cable. Needed bends were not standard 45 or 90 deg so my curves worked better than factory curves.
I heat softened it to make gentle large radius curves of ~ 3ft radius, or snake it thru labyrinth of large tree roots. It's almost as bendable as cooked spaghetti when warm. I bent gray electrical PVC conduit same way.
When I tried to make tight radius turns of say ~ 12 or 18 inch radius I had trouble with hot pipe collapsing into an oval or even pinching off. Pipe was laying on ground, so I just pushed wide side of oval down, back into ~ circular shape. I discovered if I bent all way to ends of pipe the ends got oval and won't go into mating round fittings. So I kept ends cool, wet rag even, and had no trouble.
For tight bends you'll likely have to make up some type of split forming mold to keep pipe circular. Maybe pressurize it even. Got a block of wood , dremal and some sandpaper to make a mold? Likely will have to experiment a little. Got the old part? make a plaster or car bondo cast of it.
For bending copper tubing they have a tightly coiled steel "spring" you slide over the pipe before bending. It keeps the tube circular, something like that should help somewhat if bends are not too sharp.
Other thing I've heard used to keep pipe from colapsing on tight bends is fill it with sand during forming. Never tried it.0 -
@AMservices:
This was the reason for this post ..... to get a real world measure of the threat level of working at the low end T&P of flashable water.
You can't send a hot water heater ripping thru your house and travel 200ft into the air with just 250 F @ 30 PSI. Only 2.7% of the water volume can even flash to steam at these low levels of T&P.
Also, my heated water volume (100 gallons) is not all centrally located in one bulk 100 gallon pressure vessel. This volume is distributed/stored inside a 2" pipe 100 ft long.
It is my contention that RCP on a "central tank" results in a catastrophic fast flash explosion, where as the distributed pipe container would release the flash more like if you were to simply open the end of the pipe with a water valve.
Just like a standard 30 lb pressure relief valve does on a home boiler.
Seems to me its the rate and surface area of exposure to the 14.7 psi determines severity of the flash effects ..... from a reasonably manageable failure release to a full catastrophic flash explosion.
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I am no expert on this! Below are only my GUESSES on what happens. You should research stream explosions and dangers. And consult an expert.
You said water is in pipe , but since it's easier lets first think about what might happen during a boiler explosion. Lets assume boiler is pressurized, and has a round shape .
When a boiler is over pressurized a crack may quickly propergate to a long enough length that pressure vessel material no longer has the strength to hold it's shape. And sides of crack may start to open like house doors. Once crack is long enough these so-called "doors" can tear and QUICKLY open. This suddenly creates a large opening that the pressure can quickly vent down thru ( at boiler pressure, 30 psi your pipe case). At some point the metal may completely rip and the doors become free. At that point that door mass will be accelerated by the pressure difference across it ( from newton's law F = MA) . Since the force is high compared to the mass , it can accelerate very fast. Same for the steam. It likely travels at the speed of sound, ~770 MPH. Fast, so gets called an explosion.
Also since a wall section of presure vessel is now missing there will be a net force on the vessel and vessel will be pushed in opposite direction of escaping steam, similar to a rocket ( newton's law of equal and and opposite reaction)
Now a reasonable question is will the old sewer pipe crack under your pressure, or vent out the ends..... I don't know. I've heard inspectors pressure test sewer pipes to something like 30 psi for leak testing, not sure on test pressure. Maybe your old sewer pipe will take it, maybe it won't, I don't know what condition it's in. At very least if it cracks you'll have sewer leaks, and possibly collapse of sewer pipe from soil pressure (weight of soil).
Web says soil density is~ 110#/cubic-ft, if pipe is 4ft down then soil pressure on outside of pipe is only something like ~ 3 psi.......not much help to offset pressure inside pipe.
Even if sewer pipe doesn't break, one problem that comes to mind is if your new expanding pipe bursts, then some water will stay liquid but can be pushed by steam down the sewer pipe. Bit like gunpower pressure pushes a bullet down a gun barrel. It might get going pretty fast, and water hammer if pipe makes a bend. Guessing it won't break it if in good condition but risk of it slamming your pipe curves into sewer wall like a hammer
In your picture the sewer pipe is aimed at ceiling. Risk of pulses of fast moving liquid water slamming into bend of pipe breaking it. I've sledge hammered PVC pipe, it breaks into SHARP edged shrapnel that cut me.
I would stay away from pressurized steam idea, too many potential dangers. The expanding steam can travel fast and junk it might pick up becomes shrapnel.
There might be other explosion dangers to consider, I don't know. these are just ones that immediately come to mind.
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Another idea.......stretchable bladder tube with hot oil inside your expanding pipe??1 -
I've started setting up a test fixture to see if I can expand the 2" PVC liner with a max. 212 F water temperature , but now under a variable hydraulic pressure pump (NO AIR - just increasing the water pressure).
lab conditions need only 12 to 20 psi for expanding the PVC, field conditions may require 50 to 60 psi.
Then the failure mode is NOT an flash steam explosion , but a simple stretch/tearing of the PVC pipe liner (No flying shrapnel danger either).0 -
IZOD ratings
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That Elvaloy looks like a better candidate for forming at low temp..
Looks like it's stiffness drops by ~ 100x at 190 deg
VS PVC whose stiffness looks to only drop maybe 10x at 190 deg
(vertical axis is a log scale)
Of course the next question is how will the repaired line stand up to a large pot of boiling water dumped down the drain ( lobster pot), after a long hot shower. .......Guessing it'll want to contract. That's where epoxy has the edge on thermoplastic
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What about using vinegar to increase boiling point or table salt?0
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I think that Leonard is on the right track.
It seems that people imagine that _all_ of the superheated water will instantly turn into steam if given a chance. But this would be like _all_ of the water in a pot instantly boiling away as soon as the pot reaches 212F. Rather a portion of the water will turn to steam, absorbing energy from the rest of the water and cooling it down. If you take a mass of water under pressure at 250F and expose it to atmosphere you will quickly have slightly smaller mass of water at 212F with the remainder of the water in the form of steam.
The problem is that this steam is spreading the _hot_ water all over the place. Your system design needs to consider the volume of this steam/water mixture, figure out where it will go and figure out what sort of injury/damage it could cause.
You won't have a 1600x expansion of your liquid water into steam volume...but 40x is plenty large enough to spray hot water over lots of stuff.
-Jon
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IF you dig into a thermodynamics book and look at the steam tables and enthalpy ? graphs you can likely calculate how much water will flash to vapor ( called quality factor I think it was , % vapor).
Might be able to use the enthalpy ?? graphs to calculate the energy content of pressureized superheated water compared to flashed water to see how much energy is released. This might be worst case energy available to crack pipe and move soil. Compared that energy with chemical explosives to get a handle on ability to move soil. Talk to an explosives expert.
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One method I've used to see how dangerous very high pressure air is, was to start with much less pressure and release it to see what the effect was, then repeat with more pressure each time till I finally got up to full pressure. That way I could judge the increase in danger at each step and decide to continue or stop.
I did this when i had to work with a ~ 1 pint pressure vessel presurized at ~ 1,800 psi, had a quick release electric valve and a 2ft hose (rated at 10,000 psi). I was trying to determine how much kick the 2 ft hose would have if it accidentally triggered while I was holding it. The valve was open for only ~ 1/20 th second and dumped ~ 1/2 the tank pressure thru hose in that time period. For the small ID hose (1/8 inch ??) I had it was kick I was OK with. Of course I took safety precautions to protect my self if it went wrong, including safety glasses.
If I tried it with steam I'ld want a remote open unoccupied outdoors area, with nothing to damage.0 -
@Leonard:
".... start with much less pressure and release it to see what the effect was, then repeat with more pressure each time till I finally got up to full pressure."
My thoughts exactly! ....... I'll set up a 60 ft ( length of my rubber roof deck here) two inch pipe with a fast open electric solenoid valve.
While maintaining 30 psi in pipe I'll step thru higher temperatures ( 2 degree increments) starting at 212 F and release the valve open to the outside pressure (14.7 psi).
This should give me a good idea of the size of the dragon I care to play with : )
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How does one spin a 20' stick of 2" pipe at 3500 RPM's in the field? I understand the principles behind it... Never mind, I re-read your post and realize you DON'T spin it in the field.
METhere was an error rendering this rich post.
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