What will Muriatic acid do to PVC pipe? - RC Groups
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Apr 16, 2004, 12:10 AM
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Mike C's Avatar

What will Muriatic acid do to PVC pipe?

Hey guys, I am painting my basement walls with UGL waterproofing paint. One of the steps is to remove effuence (sp?) and etch the wall with a 20% muriatic acid solution. Then seal cracks and paint with 2 coats of this paint. I am about to get to the PVC pipes that carry the wastewater to the septic system. Has anyone used this acid around plastic pipes? I guess I could go and buy a small piece of pipe and try it but in my tired, up to late brain I figured I would ask here. Thanks in advance.
Apr 16, 2004, 12:25 AM
Useful Idiot
Muriatic (Hydrochloric) acid at even 20%, about half normal commercial strength, shouldn't damage PVC plumbing pipes for the use you have in mind, i.e. fairly brief exposure. Even so, it'd be a good idea to rinse the system with plenty of water immediately. Presumably you have some means of ventilating the basement and protective clothing. Humans are less tolerant than PVC
Apr 16, 2004, 09:16 AM
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Mike C's Avatar
Ventilation? That's why I have that funny grin on my face when I finish
I have the windows and doors open and a fan blowing to the outide and I am wearing one of the lightweight particle masks to keep it off of my face. I still have to take some breaks from the fumes though. I am surprised at how time consuming it is to do this job correctly.
Apr 16, 2004, 10:52 AM
research_guy's Avatar
Tell me about fumes... I've worked with 12 Molar HCl (when you take the cap off it you can see it's volatility in the air above the bottle). At the concentration you're using it shouldn't be too bad. Just do as Martin Suggests. Just last week I was exposed to a massive amount of vaporized Paraformaldehyde... lovely stuff that is caustic, highly flammable, a suspected carcinogen, and does a fantastic job of burning your respiratory tract/eyes.

Apr 16, 2004, 11:07 AM
Go get them Meg!
lrsudog's Avatar
Muriatic acid in high concentrations is often used to remove calcium buildup from emptied swimming pools. It is usually sprayed on with a garden type sprayer and allowed to puddle at the bottom of the pool as the plaster is scrubbed with a broom or such.

Most modern pools use PVC piping, and I have yet to see a warning against the acid's use at any pool supply store where I have usually bought it, so I think that you are safe.

Even so, that's some nasty stuff, so I'd follow Martin's advice and rinse it out of the area asap.
Apr 17, 2004, 03:55 AM
Will work for planes
omega blood's Avatar
Your OK. we use 100% were I work , I use it to rmove all sorts of build up.
Apr 17, 2004, 12:50 PM
Rip th... Bring the Beer!
chemsurfer's Avatar
I'd be very careful about breathing acid vapors. It's not the same thing as breathing solvent vapors (still very bad). It literally can eat away at your lung tissue. A paper mask is no protection at all againast this since the vapor is much smaller than the space between the paper fibers. I would highly reccomend getting a proper respirator with an acid filter cartridge.

I once got a face full of acetic acid vapor (think highly concentrated vinegar). Some idiot had put their glassware in a drying oven with a trace of acetic acid still on it. When I went to get my stuff out of the oven, I stuck my face right up to it to see where things were, and got MACED! Had a hard time breathing for a minute, and had to keep my face in the eye wash for fifteen minutes (you don't know how fun that is until you have to do it ). Those first chemistry lab classes in college are dangerous since nobody know what they are doing yet.

Apr 17, 2004, 01:42 PM
Useful Idiot
Chemsurfer, I suppose you're right but anybody who's worked a while in a lab tends to be a little lax on safety measures. I remember pipetting conc. nitric using my mouth, getting the occasional mouthfull and just spitting it out. That's why there are sinks on lab benches.
Maybe Mike could break in to say he's still alive and breathing to reassure us
Apr 18, 2004, 10:36 PM
Registered User
Mike C's Avatar
Yesssiff Iba isba stilba here. noba probablemba.
So far no problems with the acid. I give the walls a couple of days to thoroughly dry before I paint. So far the proccess isn't hard just time consuming. Making sure I do it right so I don't have to do it again for a long while.
May go out and check on the price of a good filter. I have already purchased some polyethylene suits to protect my skin and clothing. I am using it very liberally on the walls.
Has anyone else used this brand paint? (UGL latex paint) How long did it last?
Apr 18, 2004, 10:38 PM
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Mike C's Avatar
Whew, I'm not superstitious or anything but the number of my last post made me want to post again quickly.
Dec 04, 2015, 05:33 AM
Registered User

Use of Hydrochloric acid on cement concrete

Hi all, I hope I can find some help here. I have encountered some choked PVC pipes with cement concrete at my work site. I am thinking to clear these choked pipes with hydrochloric acid, but I am worried it may damage the PVC pipes rather than clearing the choke.
Can anyone give advise on this? Thanks.
Dec 04, 2015, 05:51 AM
Suspended Account
Last edited by Mark Powell; Dec 04, 2015 at 05:55 AM. Reason: I thought I knew the answer but decided I didn't.
Dec 04, 2015, 07:08 AM
AustinTatious's Avatar
Doesn't it come in plastic bottles???
Dec 04, 2015, 07:18 AM
Figure Nine Champ
madsci_guy's Avatar
They aren't PVC bottles, IIRC, they are some kind of polyethylene.

Not all plastic is equal.

According to this:


Hydrochloric Acid, 1-5% Excellent
Hydrochloric Acid, 35% Good

Looks like PVC can stand up to even concentrated HCl.

This says the same thing: http://www.quickcutgasket.com/pdf/Ch...ance-Chart.pdf

Be Careful!
Dec 04, 2015, 08:01 AM
Registered User
He asked the question 11 years ago. Chances are he finished the job already.