HDPE pipe fittings leaking

[Peter.N.]

We have a well with a centrifugal pump in the pump house (small shed) with the control gear including a UV system. Its all connected together with 25mm HDPE pipe and fittings. I have just replaced the pump and several of the fittings are leaking especially once it gets up to pumping pressure (about 50 psi). I cant see why as the sealing is done with 'O' rings and they look and feel OK as does the rest of the fitting. Tightening them more doesn't help much.

Any ideas? Thanks

Peter

 

[Madrab]

Strip it all off and check that everything is clean and in the same place. The fittings use O-rings and grab rings, the grab rings tend to mark the pipe and if anything's moved then the o-rings may be sitting on those marks and then they can let by. Was the pump exactly the same? What fittings are leaking, the ones that connect to the pump or others?

 

[Peter.N.]

Thanks for your comments. The pump is near enough the same, I have replaced it several times over the years and have had this problem before but each time I dismantle it the leaking is worse. I have also had other problems which entailed dismantling so its been taken apart a number of times.

There are about a dozen joints but they don't all leak. I also have another problem, having just fitted a new foot valve because I was loosing priming water, I still am, there is one elbow where the pipe goes down the well which could be leaking although it looked fine when I refitted it so either it is leaking or the new foot valve is.

Its obviously easier to see the leaks on the high pressure side but not the suction side. I had thought about the damage on the pipes done by the clamp ring and thought I might make up some new ones but I cant do that on the well feed as I cant afford to shorten them. The worst leaks are on the pump to UV system pipes.

Its been working very well for some years, now everything seems to be happening at once.

Thanks again I will examine them all carefully

Peter

 

[Madrab]

Do you clean up the joints and grease the o-rings with a little silicon grease? Some fine sandpaper may also help to minimise the marks on the pipe. Unfortunately MDPE, being soft, can mark easily and if the O-Rings are older then they do dry up, hence a (very) little silicone grease.

The MDPE pipe ends will only take so many changes before they'll need renewed. Sometime better to make the joins that are regularly demounted in copper, so they are more resilient and can last longer.

 

[Peter.N.]

I'm just off down there to take one of the worst sections off and cut a new section of pipe. I do have some silicon grease somewhere but its quite old, I think it came from 'Radiospares'! I have a coil of pipe but its grown into a hedge so I will have to sort that out first.

Peter

 

[Madrab]

I do have some silicon grease somewhere but its quite old

That's ok, it doesn't degrade. That'll probably be electrical grease but usually all the same.

 

[Peter.N.]

Yes, it was from my workshop, I was a TV engineer for 50 years. Well a new section of pipe a good clean and some S. grease has cured it I just have about another 8 to do. Had to dig a 4' hole in the hedge to retrieve the coil of pipe, found all sorts of other interesting things under there and the battery went flat on the hedge cutter.

Peter