Novice with cutting torch question(s).

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I cannot seem to get any consistency in terms of repeated cuts.  Between cuts I shut off the torch.  I am cutting some used 2 3/8" pipe and making some H posts for wire fencing.  I have the pipe saddles to trace to make the cuts.  So far I have figured out that "not all used pipe is created equal".  Some I feel like I am cutting through two distict layers like the pipe is delaminating.  BUT, my main issue is some cuts are fast and clean while others are slow and some downright sooty.  Here is my set up and settings:  Acetylene set at about 7-8 pounds and the oxygen at about 30 PSI.  About 50 feet of 3/16" hose and a #1 cutting tip.  I lit it with the acetylene and the turn up the acetylene up until the sooty flame goes away.  I then open the oxygen valve next to until the blue flame is about 1.5-2" long and start cutting.  Not sure why the top oxygen valve is there other than fine tuning.  Is the bottom one used as merely an ON/OFF and adjustments are made at the valve closest to the tip.  I get the impression that the sooty-ness starts at times when I have heated the steel and am blowing away the red hot steel with the oxygen.  Does not always happen as there are times I must set it up right as it cuts fast, cleanly, and with a very narrow cut.  Noticing the difference in pipe has made me seriously consider only new pipe in the future.  This used pipe is from a used and poorly layed out corral I removed.  Thanks for any suggestions.
Reply:The second layer is probably a layer of rust that is causing blow back.try smacking it a few times to knock it off. as far as the torch settings  Lite the torch and then set to a natural flame so that the blue cones have sharp points then hold the ocy lever down and readjust the oxy until blue cones are as sharp as possible. open the ocy.valve just far enough to get a sharp point no farther.
Reply:Hey Cormac, welcome!    The oxy valve at the bottom of the handle is for a gas welding attachment. It should be all the way on when using a cutting head and you make your adj. on the upper valve.When you light,open the acety. and the top oxy valve just a little. That way you dont get the soot. Adjust your gas up until its as hot as you want, then open top oxy valve till you get sharp cones at the tip. they should be about 1/8 " long. Then depress the cutting lever and fine tune the flame while holding lever down. Your cones should be 1/8- 3/16 long and a full, rich, bright blue. If you have too much acet. then you get a lighter blue "feather" at the end of the cone and too much oxy gives a lighter, washed out look to the cones themselves. Hope this helps.......Have fun!
Reply:Not sure why the top oxygen valve is there other than fine tuning. Is the bottom one used as merely an ON/OFF and adjustments are made at the valve closest to the tip.
Reply:Hey Sandy, thanks for the compliment! I guess I've been called worse!
Reply:Originally Posted by TEKHey Sandy, thanks for the compliment! I guess I've been called worse!
Reply:Something nobody prolly thunk of here....when you aint using your torch always shut off your lower oxygen valve.  I cant tell you how many empty bottles Ive found cause the danged leveer was either been depressed byt he weight of the torch hangin off somwhere, or there just a leaky valve.  Anyway, its always a good idea to keep that sucker off when you aint using the torch for more than 10 or so minsCHRIS
Reply:TEK and Sandy have covered it pretty well, I'd say.Couple of things to add though:1 - Oxygen Valves.  The bottom oxygen valve controls the absolute maximum flow of oxygen that will pass through the torch tip (i.e. preheat flames in the outer ring + center cutting oxygen jet).  Open it right up when cutting.  The "top" valve (part of the attachment rather than the handle - i.e. the one that's NOT right next to the acetylene valve) is called the oxygen throttle valve.  This controls only the amount of oxygen flowing through the preheat flames.  Now, if you don't open the bottom-most valve fully you can have a situation where there's not enough absolute flow of oxygen through the preheats AND the cutting flame put together - think of filling a bathtub with an eyedropper.  This would lead to sootiness when hitting the cutting oxygen lever - "you can't please all of the people (flames) all of the time (at the same time)" if you don't have enough oxygen to pay both Peter (preheats) AND Paul (cutting stream).2 - Hand placement.  Some pin valves (like the ones mentioned above, for example) will exhibit decreased flow if you press on them.  You may want to set up your torch (lit and tuned to a neutral flame with the cutting lever depressed) and push on each valve individually to see what effect it has.  My bets are:-Throttle valve: preheat cones will get slightly longer with pressure on the valve knob; may or may not see flame going slightly carburizing - longer, softer cone protruding past the smaller preheat cones-Bottom-most oxygen valve: preheat cones will get slightly longer with pressure on the valve knob; very likely to see flame becoming carburizing as described above; hard enough pressure might get you some yellowish flickering at the end of the flame indicating an extremely rich condition-Acetylene valve: preheat cones will get slightly shorter; too much pressure may cause flame to flash-back and blow the torch outThe reason I go into this sort of detail is because if you're holding farther back on the torch handle, and wearing heavy gloves as most of us do when flame cutting or welding, you MAY be unwittingly putting pressure on the oxygen valve and creating an acetylene-rich condition (and thus a sooty deposit).MR
Reply:Your pressure is WAY too high for small pipe.  Drop your acetylene pressure down around five or less.  All you need is twenty on your oxy.  A number 1 is even a bit large for pipe.  Avoid a roaring flame from your preheat cones.  The material is very thin and overheating just melts things making lots of grapes.Also in case you don't know all you need is a slight crescent cut out of each side of the pipe end.  You don't have to cut anything else.  For 2 inch pipe cut down slightly less than 7/8th on each side leaving the points square.
Reply:Wow!  Thanks for all the detailed and informative answers.  Also, thanks for the welcome.  I'll try all your input this weekend.  With excellent information like you offered, you guys just may be creating a cutting torch pro here.  Again, thanks.
Reply:Here how i do it in class..Acentalyne - 5 psiOxygen - 25 psiTurn on Gas and light, turn up till all the soot goes away.. then with the top, single valve off, turn on the oxygen valve at bottom about 1/2 turn.. then WithOUT touching the oxygen lever, turn the top value on slowly.. you want the small blue flames to be bullet shaped, not sharp but not round.next, push the oxygen level, the small blue flames should not change shape or size.. the noise will go up and you may see more of the light, see-thru flame but the small ones directly at the tip of the torch should remain the same..
Reply:I think you have it too high on your settings,but it depends on your torch and what you are happy with.You might be going too slow causing some of your trouble,and on the used you can try cutting on the side to where the flame is going through the metal but not so much inside the pipe,I think if there is a lot of scale inside that might work where it doesnt seem like you are cutting through 2 layers.