ivars21 Posted July 2, 2013 Posted July 2, 2013 (edited) Hi, I have a question about PE (polyethylene) pipes.Here, in Latvia there are no such qualification as HDPE pipes, all PE pipes are categorised by maximum holding pressure.For example, there are few tubes which holds up to 16 atmosphere (PN16) which is around 16.2 bars, also PN10 tubes which are around 10 bars.So the question is - at what pressure do pipes start to classify as HDPE? They are black with blue line if it changes anything, also does these kind of PE tubes explodes like HDPE and could be used for mortars? Thank you! Edited July 2, 2013 by ivars21
helix Posted July 2, 2013 Posted July 2, 2013 PN ratings normally apply to flanges, not to pipe. HDPE and MDPE pipe used commonly for gas and water services normally have a SDR rating (standard dimension ratio) which relates the wall thickness to the pipe outside diameter for smaller diameter tube SDR11 and 17 are common in the UK at least. SDR11 tube will have a wall thickness of an 11th of the pipe OD from memory and therefore can handle higher pressures than SDR17 pipe of the same nominal bore. If you do a search on google you should get pressure ratings for whatever grade of plastic and SDR you have. PE tube can be used for mortars have a look at this site http://www.mighty-mite.com/files/MMM%20Specs%2001-28-13.pdf 1
Arthur Posted July 3, 2013 Posted July 3, 2013 PE and HDPE are slight differences in the compounding of the polymer plastic.They are used for mortars because they are strong and water resistant (check the plug!) But their prime advantage is their mode of failure -they stretch then split if overloaded. Other building plastics (ABS and PVC and polystyrene) simply shatter and make a LOT of shrapnel. 1
Mumbles Posted July 3, 2013 Posted July 3, 2013 From what little I've heard about the different types of polyethylene, anything made from that material should be fine structurally. While I've personally never used anything except HDPE, there are many reports of people successfully using Medium density polyethylene (MDPE). I've never heard of LDPE tubing of the type we'd use, I suspect it'd be strong enough as well. The plug is always the weak point in a PE mortar anyway. By far the most common mode of failure is the plug cracking or being pushed/torn out of the bottom of the mortar. The stretching and turning into a banana really only happens when salutes or strong breaks go off inside the gun. 1
Arthur Posted July 3, 2013 Posted July 3, 2013 If your PE or HDPE pipe is intended for water or gas mains then it's WORTH A TEST. I plug PE mortars by drilling holes round the base and fitting nails about OD/3 long and about an inch up the tube. Then cover the bottom with masking tape and pour in about Bore/3 of polyester resin (filled with dry sharp sand or chop strand glass matt In a 6" mortar a 2" plug has worked for me it stays in place because of the nails through the tube.
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