Removimg concrete from mdpe pipe

[reb78]

I have a leak on a section of 25mm mdpe in a manhole. The pipe.running through the manhole has dried concrete splashes along it. What's the best way to remove this without damaging or scoring the pipe so that the o rings in the connectors I will need to use to splice a new section in will seal?

Excavating either side of the manhole isn't alreally an option as the sides are concrete and it's at least 4 ft deep and one side is under a drive.

 

[Mark 5]

I have a leak on a section of 25mm mdpe in a manhole. The pipe.running through the manhole has dried concrete splashes along it. What's the best way to remove this without damaging or scoring the pipe so that the o rings in the connectors I will need to use to splice a new section in will seal?

Excavating either side of the manhole isn't alreally an option as the sides are concrete and it's at least 4 ft deep and one side is under a drive.

I'm reaching on this one as I don't know but as it's concrete splashes, me I would give a go with Spirit of Salts, brush/spray it on as best as, it's thin, leave for 30 seconds or so and its wipe, wash down with water and repeat as required.

Don't think it would harm the MDPE, might dull the colour.

Marigolds and eye protection a must.

 

[angellonewolf]

brick acid ? you could try it on a bit see if it melts it first

 

[Agroshield]

...you could try it on a bit see if it melts it first

Brick acid is bought in a plastic container, so the pipe is unlikely to be affected.

Vinegar or citric or phosphoric or battery (sulphuric) acid would also work. Even Viakal would be worth a go.

Neutralise it after so when your hands are in there fixing the pipe, the skin remains on them.

Squeezing the splashes with a set of pliers, perhaps with the lower jaw protected with tape, could crack it off.

Gentle rubbing with a green pan scrubber would not damage the pipe.

 

[reb78]

Thanks folks. I do have some brick acid somewhere in the shed. I bought that to remove melted aluminium piston from a hard coated chainsaw engine bore! (It worked on that!)

I'll get on this today. This pipes a nightmare. I'm responsible for over 1.25 miles (yes, miles) of it after the meter!

 

[mark roberts]

Once you have found that brick acid you might want to leave it out of the shed. Thats if you have anything metal like tools or machines in there. Apparently just by having the sealed container can cause rust of stuff.

 

[knighty]

if it's just splashes put some decent gloves on or grab a rag and try giving it a good rub first, chances are it might just rub off

 

[reb78]

if it's just splashes put some decent gloves on or grab a rag and try giving it a good rub first, chances are it might just rub off

It has thankfully. I think the pinhole leak has soaked the splashes for a short while and made them soft.

The pipe is fairly scratched where it's been in the ground before I dug it out. I'm going to try and find the smoothest places to put the joints but how tolerant are the fitting o rings of scratches? I can feel these with a fingernail. Not sure whether to scrape/rub back with something or if that will be worse.

 

[Bornfree]

It has thankfully. I think the pinhole leak has soaked the splashes for a short while and made them soft.

The pipe is fairly scratched where it's been in the ground before I dug it out. I'm going to try and find the smoothest places to put the joints but how tolerant are the fitting o rings of scratches? I can feel these with a fingernail. Not sure whether to scrape/rub back with something or if that will be worse.

The philmac fittings are the best for scored pipe as they have a large soft o ring that gets squashed into the pipe surface when you tighten the nut.

 

[dobbslc]

The O rings in those fittings are normal quite soft so will take up a fair bit of roughness.
We used Gripper fittings on our site temps water supplies and they take a fair beating.
talbot grippa universal mdpe adapter 25mm 3/4 inch 27 34mm https://www.monsterplumb.co.uk/talb...k1crRGL0uBFp13KU-BPT9y16QPaJJlCoaArhfEALw_wcB

 

[dobbslc]

Ha ha @Bornfree we kind of crossed the streams there !

 

[Agroshield]

Not sure whether to scrape/rub back with something or if that will be worse.

A hot something that smoothes out the plastic (clothes iron, soldering iron, heated up scraper blade) might work if required on really bad ones, but the O-rings are quite tolerant.

 

[voipio]

Scratches along the pipe axis are the problematic ones, with regard to sealing in pipe connectors. Circumferential scratches, less so. A heat gun, or blowlamp could be used to "heal" the pipe surface, once it's been cleaned up, but practice on a piece of scrap pipe first.

 

[knighty]

unless they're deep scratches it should seal up just fine

worth trying first before you do anything else

 

[reb78]

Thanks everyone. Success. I had a stop tap on the shelf that needed about 2.5 inches taking out of the pipe to fit it. So I looked for the smoothest places for the seal lands either side of the leak and it seems leak free currently. We are a fair drop (600m I think) down a hill from the main so we get pretty high pressures here. I think there's a problem buried somewhere by the previous owner but still see 6 bar at the taps.

We damaged this pipe with a digger when we were last looking for a leak and locating the pipe. It didn't leak at the time so I built a manhole around it with the intention of cutting out the damage and putting a stop tap there at some point. Well, that point arrived last night!

 

[voipio]

A 600m drop will give about 60Bar (900psi) static pressure at the tap at the bottom, unless there are one or more pressure regulating valves, or water tanks with ball valves, fitted somewhere along the line.

 

[reb78]

I'm mixing ft and metres. Sorry. It's a 165 metre drop from the meter to our house which is about 550ft. Still a fair pressure due to the hill though.

 

[Agroshield]

I'm mixing ft and metres.

Are there any regulations concerning the maximum pressure the water company is permitted to supply at? It could be worth checking they are not exceeding them.

If they are at the top end of their allowance, the advice about a pressure regulator may be good, especially given the length of your responsibility.

Installing one at the beginning of your part and adjusting it until the other end is comfortable would give everything you own an easier time.

 

[reb78]

Are there any regulations concerning the maximum pressure the water company is permitted to supply at? It could be worth checking they are not exceeding them.

If they are at the top end of their allowance, the advice about a pressure regulator may be good, especially given the length of your responsibility.

Installing one at the beginning of your part and adjusting it until the other end is comfortable would give everything you own an easier time.

We may do that - PRV just after the meter. There are four supplies that come off of four meters there and go varying distances down the hill. The neighbour has a leak in that spot. They are all old black alkathene at that point and all become blue somewhere on their run. I think the leaks are there as they sit over a gas main. That was installed in 2018 and the crew digging the main went through all four and I'm certain they were joined back up with little care!

 

[reb78]

The offending part today. Kinda weird as it looks like it got eroded around the damaged section from inside out.