CWB backing plate removal question

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Work has requested us to certify with the CWB structural plate test. This is a new cert for me as all my tickets have previously been TSSA pressure pipe.According to the CWB website our plates will be cut into 3 pieces for bending with the 2 outer pieces (with tie ins) being root bent and the center piece being face bent.My question is the procedure for removing the backing strip. Is the backing strip removed by cutting torch? grinding? gouging? or machining? or is any removal process acceptable for the backing plate?JasonLincoln Idealarc 250 stick/tigThermal Dynamics Cutmaster 52Miller Bobcat 250Torchmate CNC tableThermal Arc Hefty 2Ironworkers Local 720
Reply:Originally Posted by snoeproeWork has requested us to certify with the CWB structural plate test. This is a new cert for me as all my tickets have previously been TSSA pressure pipe.According to the CWB website our plates will be cut into 3 pieces for bending with the 2 outer pieces (with tie ins) being root bent and the center piece being face bent.My question is the procedure for removing the backing strip. Is the backing strip removed by cutting torch? grinding? gouging? or machining? or is any removal process acceptable for the backing plate?
Reply:When I done my tests at the local iron workers union they were x rayed.  The people who were tested at the school I went to theirs were bent everyone used a torch for the backing strip.  When we did our bends for school (for the course not certification) we gouged the backing strips off (arc air).  When we did this and bent our pieces in the schools press small cracks would appear  along the lines or path we gouged.  I would be concerned these cracks would cause a CWB inspector to fail a person.If it were me id go for the torch.Heres a video on the CWB test   [ame]http://www.youtube.com/watch?v=yukp9290KbM[/ame][ame]http://www.youtube.com/watch?v=MVzajQifzMs&feature=related[/ame][ame]http://www.youtube.com/watch?v=piozISiX7jo&feature=related[/ame][ame]http://www.youtube.com/watch?v=Wp_TbYrC94g&feature=related[/ame]Last edited by Newfie_1986; 01-22-2010 at 11:49 PM.
Reply:when I tested used a torch to cut off backing plate just be careful not take off too much can ruin a good test plate
Reply:Excellent info, thanks guys. The CWB vids were helpful. They make no reference to removing the backing plate though.From my understanding, we're using smaw process with E7018 1/8 for our test. Our coupons will be bent.Last edited by snoeproe; 01-23-2010 at 12:29 AM.JasonLincoln Idealarc 250 stick/tigThermal Dynamics Cutmaster 52Miller Bobcat 250Torchmate CNC tableThermal Arc Hefty 2Ironworkers Local 720
Reply:In my aws cert class, they cut the backing strips off with a band saw after cutting out the coupon strips from the test plate.MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op
Reply:We use a portaband or a grinder.
Reply:most I have cut off with a torch, when i have had a air arc, i gouged it off.  I prefer to torch them off.  that gouge is sooo easy to dip it too deep and ruin a test.Last edited by Scott Young; 01-23-2010 at 09:56 AM.
Reply:i would have to say if the standard does not specify how to remove it, then it does not matter. if you use a torch and screw it up, use that sample as a face bend instead of the root bend. i have heard a file works good at removing a backing strip too. you could be there awhile though!
Reply:[QUOTE=El_Lloydeo;353678] if you use a torch and screw it up, use that sample as a face bend instead of the root bend. QUOTE]The thing with that is you have no choice in what becomes a face or root bend.  The CWB has that specified already.  The procedure is to number the coupons from left to right 1,2,3 odd numbers being root bends and even being face.  If I recall it shows that in the videos I posted above....  Also somethings I forgot to bring up.  You most likely already know this though.  No more than 1/8th inch buildup.  Your root passes are not allowed to be any more than 8mm wide.Last edited by Newfie_1986; 01-23-2010 at 01:42 PM.
Reply:ahhhh gotcha! never checked out anything cwb as i am an american! but who will really know! i wont tell if you dont!
Reply:The inspector watches and stamps your plates before you weld them.  No fooling him lol
Reply:yeah we do the same where i work. but when we test them we are all by ourselves. what i was saying is that the inspector takes the messed up sample and use it as a face bend, which i have done before. but in d1.1 for a simple welder qual, i dont see that it makes a difference which is the face or shich is the root bend. seems like there is a reference to it on a drawing but i never really have paid much attention to the left side and right side. i have a tough enough time making sure i get a root and a face instead of two faces or two roots most of the time!
Reply:When I have taken the AWS unlimited test for 3/4G the plates are cut with a marvel saw and then once we have the coupon area cut out then you can tak the coupon and place it in a vice and then with an adjustable(crescent) wrench you can literaly snap off whats left of the backing bar. Then you touch things up with the grinder and away you go to the bender.My suggestion would be to tack the backing bar in about 3 places on each side of the bar. Be sure that your tacks are not in the coupon area. So grab a tape and measure out and mark the coupon locations then tack away. If you have pass pressure vessel tests with stick this will be cake. If you are doing the unlimited test for all positions, typicaly a 3 and 4G test, you can plan on just around 4 hours to complete the test.'Mike
Reply:the thing is though with a side bend test the backing area is quite small compared to a root and face. impossible to snap them off with these kind of bends. we do that all the time with the 1 inchers but the limited tests.....no can do. we started testing ppl on 1/2 inch plate and that gives them a little more welding they can do instead of the 3/8s plate. and we can still do the side bends on them. makes it nice when you can just twist the backing off.
Reply:Every test I've ever taken with a backing plate, just used a mill to take it off.   Fast, cheap, accurate.   30 seconds and it's done.
Reply:Our test plate is 3/8" thick, one side beveled, one side square edge. The backing plate is 1/4" thick. The 2 outer pieces cut must be root bent cause they went to root bend the 2 tie ins on each sample. We're doing all 4 positions, flat, virticle, horizontal and overhead. I do have my P-1 pressure pipe smaw ticket already. Also have my P-8 pressure pipe SS gtaw ticket.Any of you guys switch to straight polarity for the smaw overhead cwb plate test piece with 7018?JasonLincoln Idealarc 250 stick/tigThermal Dynamics Cutmaster 52Miller Bobcat 250Torchmate CNC tableThermal Arc Hefty 2Ironworkers Local 720
Reply:AC or DCEP is what 7018s should be ran on.  Just looked in the Bible (as they call it on here).  I ran my overhead on reverse same as the other positions.  Ran all 4 plates at the same amperage (120 amps).  I let my vert cool to cap.You should have no trouble.  Im only a first year apprentice and managed to pass you should be able to.    When you grind your coupons remember to grind parallel with the way your coupon will be bent.  If you grind across the coupon the grind marks can lead to cracks opening up. Id say you already know that though.
Reply:air arc to remove the bulk of it, finish it up with a grinder and buff on teh belt grinder.i ran all mine 1/8" rod at 115amps. get a couple peices of scrap to get your setting thoguh.DCEPupgraders (people who came in for the test, not students) plates were sent off for machineing.  but we got a huge price break to do tack up and prep our own plates.  if you have your pwps you should have no problem at all
Reply:When I had to do the tests in school we had a choice of air arcing them off or oxy/feul gouging. I preferd the air arcing because i could gouge off either side of where strip where it wasnt welded, then turn the plate on edge and gouge the 1/2 inch remainder off until it was down enough a quick grind was needed. This method is really effective since u dont have to worry about gouging into the plate, if i had an air arc id do one up to show how to do this.Nothing Ever Got Done By Quitting, Never Give Up.