Leaking oil line.....weird one

[Bunker]

Been to a custard this week, bit of a friend of mine.They've had a weeping nut on the tank end of the line for a while, didn't want to trouble me so chummy covered it with some leak paste/ hardening stuff. Funnily enough that didn't work so they called me in.
I broke the nasty stuff off and re-made the connections in my usual manner, inserts, heldite etc (yes yes but I dont do flared sorry )
Anyhoo, it was still dripping the next day so I went back. We found oil was coming out of the insulation, cripes says I...I dug up what I could, just about 3' and stripped the plastic back but no damage, the rest is under the patio.
I wondered if it was residual oil from the old leak, twas a very hot day and perhaps it was expanding upwards? So I emptied the line and pressure tested to 1 bar over 45 mins. Didnt drop a smitch, perfect. Hurrah we all said, just residual.
Nope. just emailed me again to say its still coming out..

How one earth can this be happening? Anyone had this before?

Thanks

 

[Best]

Kerosine can be so penetrating. The fine grooves in the inner part of the pvc protective coating can act like a capillary joint, I suppose.
Just be careful there is not a pin hole in the copper somewhere. I have seen water/dirt ingress into oil lines causing them to leak on the lower parts of the pipe where the sentiment lies. Often caused by oil tube sight gauges letting water in & nobody doing a thorough service.

 

[lame plumber]

leaky olive, try flaring

 

[Bunker]

Turns out there was a pin ***** hole in the line 4 metres away, no damage to the insulation. I reckon the pressure test didnt show anything as the air was hydraulically locked in by the kero in the sleeveing! Must up the pressure next time..

 

[Best]

Turns out there was a pin ***** hole in the line 4 metres away, no damage to the insulation. I reckon the pressure test didnt show anything as the air was hydraulically locked in by the kero in the sleeveing! Must up the pressure next time..

Thought that was likely. Do you think the pipe is rotted from the inside?

 

[bright spark]

This sounds mad but I've seen oil lines pass pressure tests and still b leaking. My tip would b if there's signs of oil coming up, dig it up and replace it. It's it's a buddy sure he'll prob do d dig 4 ye.

 

[Best]

Oil pipes, even pvc coated, should always be inside a sleeve pipe and sleeve up well above finished ground & floor levels. That way oil line is well protected from accidental damage with a spade etc and if it leaks you will see the oil plus it might be possible to pull a new pipe through the sleeve.

 

[Millsy 82]

Completely off topic.

I once spoke to a mechanic saying about a possible leak in my air conditioning and I said it's been tested and recharged but still not working. He said how did they test it as some pressure test it but once they put the pressure in all the fittings and pipe swell up hiding all the leaks, the best way to do it is by removing all the pressure in the pipe causing a high negative pressure and see if it pulls air in. This way stopped the fittings from swelling up hiding the leaks.

Could this not be the same on the oil line? The pressure itself his the leak?