jukka Posted December 4, 2009 Posted December 4, 2009 I noticed on my local hw-store HDPE-pipes, ID 3".Is that the same pipe that is used in mortars? 6m 3" HDPE-pipe ( for some reason in here they call it PEH-pipe) costs here ~30€. I was planning to do 6 3" mortars from that with length of 450mm and clay plug 50mm.
Arthur Posted December 4, 2009 Posted December 4, 2009 Check very carefully that they are polythene please. MANY (most but not all) domestic pipes for underground use are PVC. With the differnce in properties it's wise to be really careful. Pro plugs are not clay for repeated use (thats for the Chinese for single use) Pro plugs are often timber machined to a gentle press fit and then pegged in with nails or screws. Tubes can also be plugged with resin poured in, pegged in well while pouring!
Ericz Posted December 4, 2009 Posted December 4, 2009 Just dig your mortar very deep , like 10 cm above the ground what sticks out. That will word , the ground is your endplug. grtz
Arthur Posted December 4, 2009 Posted December 4, 2009 May work but that is neither best practise or safe working. A 3" shell is enough to remove a hand or cause major burns, please take professional care.
Mumbles Posted December 4, 2009 Posted December 4, 2009 I've dug in pipes and it doesn't always work. Eventually the gasses will escape out the bottom of the pipe, and up around the sides, and you will be left with a low break.
TheSidewinder Posted December 4, 2009 Posted December 4, 2009 As has been said: Make damn sure that's really HDPE, and not PVC or other material. Clay plugs aren't going to last for more than a shot or two. You want these to last, right? Make a good wood plug, at least 2" thick, very slightly oversize, tap them into place, then use wood screws at least 2 inches long. Pre-drill holes to prevent splitting the plug. Digging them in without a solidly-plugged end is just asking for trouble. (And while you're at it, put a 2x4 or 4x4 plank at the bottom of the trench, then the mortars on top of that.) Sandy soil is the worst but even heavy clay soil isn't going to work for long, as Mumbles pointed out.
jukka Posted December 4, 2009 Author Posted December 4, 2009 (edited) I have done my study on this issue, PVC is not even considered for this purpose. But if that is made from polythene and Ill lathe the plug from some tenacious wood, glue and screw it, may that be then used (from safe distance) to shoot shell from a rack?Ill start with smaller shells but would love to build at the same time the whole set. Edited December 4, 2009 by jukka
TheSidewinder Posted December 4, 2009 Posted December 4, 2009 If it's actually HDPE, and you plug it solidly, then yes it would be suitable for a rack mount. If you're going to rack-mount, make sure the rack has a 2x4 or 4x4 plank as the base on which each mortar rests. I made a 2-inch rack for the WPAG 2 years ago, using the method I outlined, and it's still going strong.
Arthur Posted December 5, 2009 Posted December 5, 2009 If you are certain that it is HDPE then with a good plug you are ready to go in a professional manner, Good luck, you've found a bargain. It's fine to dig mortars into the ground or stake them up if there are only a couple. with a good shell lift, a mortar will go into the earth a little (or in soft ground a LOT!).
gordohigh Posted January 3, 2010 Posted January 3, 2010 You have probably already made the mortor but for the sake of others reading this, some of the local wholesale plumbing supplies sell what they advertise as HDPE sewer pipe which is actually a high density foam core with pvc on both sides of the sandwich construction. Beware, it will shatter just like regular sch 40 pvc and be dangerous to use. A good indicater is that it is white and if you look you can see the foam core.
jukka Posted January 4, 2010 Author Posted January 4, 2010 yeah, mine pipes where black with blue stripes on it. And it is called also as PEH.Dont know how much this would be useful information but I noticed that those pipes do have different pressure classes. I bought the highest one witch was 10.
a_bab Posted January 4, 2010 Posted January 4, 2010 Your pipes are certainly HDPE. The easiest way to tell is that PE is a "soft" plastic. It feels soft and greasy to the nail. PVC is hard and brittle. The pressure rating will affect the wall thickness; you may have got the highest, hence thick walls. I'd guess some 5 mm or more. This is of no importance since you make your own shells and not use commercial ones (they may not fit). Just go with your "own standards". As about the blue stripes, they are for "water use"; yellow is for gas (these pipes have very thick walls, not good for fireworks).
andyboy Posted January 4, 2010 Posted January 4, 2010 I use the black pipes with blue stripes and they are great, for more reading about pressure/use and colour coding: http://www.engineeringtoolbox.com/pe-press...ades-d_668.html I plug my pipes this way: 1. Pre-drill some holes where the plug should be and get some long screws in there.2. Place the pipe on a flat surface that doesn't absorb water.3. Pour in cement.
a_bab Posted January 4, 2010 Posted January 4, 2010 If I understand correctly, the concrete will shrink a bit leaving a small gap. Is it true?I was told that the next step could be a bit of epoxi resin (like for making fiberglass items). I use wood for my plugs.
Bonny Posted January 4, 2010 Posted January 4, 2010 If I understand correctly, the concrete will shrink a bit leaving a small gap. Is it true?I was told that the next step could be a bit of epoxi resin (like for making fiberglass items). I use wood for my plugs. I also use wooden plugs, but I bought mine that way.
Swede Posted January 4, 2010 Posted January 4, 2010 There aren't many adhesives that will actually bond to the HDPE, but some will definitely help seal. I'd turn my end plugs of hardwood for a relatively east fit, then coat the OD liberally with a regular 2-part epoxy. Slide the plug into the tube. The epoxy will act as a lube and make it easy. Allow the epoxy to set, which will create a gas-tight seal. Next, you MUST use heavy wood screws in pre-drilled holes, I'd go with 6 in a hex pattern using stainless steel. The epoxy is only to seal, not to bond... the screws provide the strength. In some cases, you can find wooden round stock that will fit the ID, making the job much easier, as you don't have to turn the wood round in a lathe.
gordohigh Posted January 13, 2010 Posted January 13, 2010 What are you guys using in a 33 inch deep by 6" HDPE mortor? I was thinking about cutting plugs from a 2x12 and putting them in 3 deep with epoxy in between and then screwing each one with stainless screws. Of coarse I will be mounting these in the ground at least 2/3 deep. I know pyrodirect sells plugs but the bigger ones are fairly expensive and the shipping would add to that. Is there a better way to do this? On another note, I just got some 2" mortors from pyrodirect and for about 2 dollars each they came with plugs already installed. I built my rack yesterday and it turned out really nice.
Bonny Posted January 13, 2010 Posted January 13, 2010 What are you guys using in a 33 inch deep by 6" HDPE mortor? I was thinking about cutting plugs from a 2x12 and putting them in 3 deep with epoxy in between and then screwing each one with stainless screws. Of coarse I will be mounting these in the ground at least 2/3 deep. I know pyrodirect sells plugs but the bigger ones are fairly expensive and the shipping would add to that. Is there a better way to do this? On another note, I just got some 2" mortors from pyrodirect and for about 2 dollars each they came with plugs already installed. I built my rack yesterday and it turned out really nice. 3 deep should be fine for a 6" mortar. I wouldn't bother ith epoxy, wood glue will be fine. Nothing really bonds well to the HDPE anyway, that's what the screws are for. Be sure to pre-drill the holes so you don't split the wood. try and cut them so they are a snug fit that needs some "persuasion" to get in. Do you have access to a lathe? If so, glue up the blank and turn to size. If not, try and cut as round as possible (unless you have a giant holesaw). If they are no totally round, to better seal the bottom of the mortar, you could always pound in a few layers of carboard (not corrugated) on top of the plugs.
dagabu Posted January 13, 2010 Posted January 13, 2010 There aren't many adhesives that will actually bond to the HDPE, I will look for the link but I thought that I read in the BAFN that there was a guy that heat sealed the mortars by heating the ends up to melting temp and molding the plug out of the melted end. It may have been in the for sale section...
Arthur Posted January 13, 2010 Posted January 13, 2010 If using HDPE pipe from another industry, do please be very careful with the dimensions. Pyro mortars are defined by their bore, water and gas pipe is defined by its outside diameter. Lots of HDPE civil engineering pipes have a bore just less than a useful firework measure, lots of pyro tubes are just a little over nominal bore.
dagabu Posted January 13, 2010 Posted January 13, 2010 If using HDPE pipe from another industry, do please be very careful with the dimensions. Pyro mortars are defined by their bore, water and gas pipe is defined by its outside diameter. Lots of HDPE civil engineering pipes have a bore just less than a useful firework measure, lots of pyro tubes are just a little over nominal bore. Take a look at the resellers pages for pyro mortars, they should have the "D" number for the tube, this is an industry number for the tube and the ID should be the same day in day out.
Bonny Posted January 14, 2010 Posted January 14, 2010 Take a look at the resellers pages for pyro mortars, they should have the "D" number for the tube, this is an industry number for the tube and the ID should be the same day in day out. Actually, on HDPE pipe, unless SIDR is used (and I don't think it ever is for mortars)... it IS the ID that changes with the wall thickness.Pyro mortars are made from SDR (Standard dimension ratio) HDPE pipe. The wall thickness x (SDR#)=OD of pipe. 3" pipe with a thicker wall = smaller ID. See here:http://www.bdiky.com/specifications/pdfs/S...Web%2012-05.pdf
dagabu Posted January 14, 2010 Posted January 14, 2010 Actually, on HDPE pipe, unless SIDR is used (and I don't think it ever is for mortars)... it IS the ID that changes with the wall thickness.Pyro mortars are made from SDR (Standard dimension ratio) HDPE pipe. The wall thickness x (SDR#)=OD of pipe. 3" pipe with a thicker wall = smaller ID. See here:http://www.bdiky.com/specifications/pdfs/S...Web%2012-05.pdf Thanks for the correction and the list!! SDR number then...
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