I"m building a suicide perch for my car.My question is Is it ok to use a piece of schedule 80 pipe.I chose this pipe because it fit the frame chanel perfectly. I"ve welded the spring plate to the pipe already and mocked my front end using this pipe,but haven't tacked it to the frame yet.I've since learned that there is a difference between pipe & tubing.Tubing being brittle?The pipe is 1/4 thick The plate is 1/2 thick will it break. Every guy with white hair says it will be fine. All the young guys say its no good.I will do it over if i have too but, would like to leave it.
Well that stuff wasnt made to make cars from it was made for plumbing. Brittle ? tubing? Never heard of that one but i do know there are bunch of different types of tubing and they do make some that should work instead of schedule 80. Dave
I wouldn't take the chance with black pipe. A lot of the white-hairs did a lot of **** back in the day. How do you think the Suicide Mount got it's name? Have any broken off recently? On the young guys cars? Maybe proper tubing is a better idea. If you look at a lot of old time rods you'll see some scary ****. Please don't give the state governments another reason to call rods unsafe. Get the tubing and a new $10 spring perch and be safe about it. I may even have some tubing at a discounted price. What OD you using?
I agree ^ some guys used that pipe for roll cages and would not even p*** NHRA inspection. We have made tube ch***is out of MS and CM tubing 1 5/8 to a 1 3/4 OD it is not hard to find and does not coast a lot for the safety side of it.
maybe the HAMB metallurgist can chime in here but I think typical schedule 80 pipe is welded, it's conceivable that it could split under the twisting stress of a spring perch load. I would think again about using 1/2" plate here too, the too heavy material can tear away easier from the lighter gauge tube
It should be fine. Most people don't understand what schd. 80 means...it means it's twice the thickness of the schd 40 black pipe that most people are familiar with. It won't be as smooth on the outside as tubing but strength wise it's over kill in MHO. They make nuclear power plants out of it...
I have to agree with Tommy This will be fine, I work in the Oil feilds & the #80 Pipe we use out there IS NOT Plumbing Black pipe. This pipe is used for structural purposes and is WAYYYY over kill for the cross member mentioned. The stuff i am used to see'in in the Field IS NOT seemed, Thick as Hell, Non-brittle weldable Pipe. We use that #80 pipe on repairs for Lufkin Pumping unit Pitman Arms, Though larger than a cross member, Same deal with much movement & pressures the could rip **** apart. I think a pic need to be posted & some of you guys need to address the fact that there is "OTHER" pipe than just "BLACK PIPE".
+1 for what De Soto said...I'm a steamfitter, we use that stuff daily. The term 'black pipe' refers to steel pipe intended for pressure service, not to be confused with cast iron '**** pipe'. Carpenter didn't say what size he's using, but for example, 2" sch.80 has a max. working pressure of 551 psi at 400*F. Just remember, the part is only as strong as your welds!
The pipe o.d. dia. is 2 3/8 On the schedule 80.Out of 8 replies 5 said not to use it,3 said it would be fine.It won't break the bank i think i'll replace it with tubing.May wanna pop some wheelies someday.Thanks for everyone's advice.
As an additional note, from what I know about pipe vs. tubing, although made of similar alloy structure, the content is not identical and pipe tends to be more brittle, especially in a twisting motion that could occur from a suicide perch. Most pipe also has a rough outer "skin" or "texture" and that can easy contaminate and compromise the weld quality.
Certified high pressure pipe welder here. My 2" pipe welds routinely p*** x-ray. Properly prepped, there will be no contamination in the weld. Can't knowledgeably comment on the twisting forces a suicide perch will put on pipe. But I can tell you I made bends in 2" schedule 40 pipe with a cheap Harbor Frieght hydraulic bender and there were no issues with splitting or tearing. As an aside, to certify high pressure, sections are cut across the weld. They are then bent into a U. Any fracture or tearing and you fail to certify. I think that eliminates any notion of brittleness. 54chop
It looks like you might be adding a lot of steel, in terms of weight, and not necessarily gaining any safety! Here's a table of wall thicknesses, and I didn't see one that was 0.25" wall. Tubing has known quality levels and can handle the torsion and bending loads. "Iron pipe" is heavier(wall) and lower in quality than most tubing available. DOM might be a good place to start for a tubing choice. And the perch thickness would benefit from using a braced 1/4 or 5/16ths depending upon the loads expected. http://www.engineeringtoolbox.com/nominal-wall-thickness-pipe-d_1337.html
I wouldn't plumb my house with DOM tubing and I wouldn't cage my car with schedule 80 pipe. But I have used a DA and an airfile to finish drywall.
I had a set of headers made out of sch 40 and a drive shaft made out of the same ****. I got new stuff now. GWAR!!!!!!!!!!!!!
it will be fine, what most people don not relize it that when you make a frame it must be triangulated to be rigid enough to carry a load, in a square tubeing being welded its not that strong and will bend and eventually break welding with pipe, tubing - do not use cast - or what ever you want to call it is much stronger !!!! it wont break on you, and will allow flexing anf twisting in the frame and it will come right back to where it belongs without ever breaking i use schedule 40 for alot of my frames including commercial and private uses go ahead and use it, most of the guys here give you opinions, they dont work with it on a daily b***is, and the ones that do use it daily know how to weld also - welds are the biggest failures
I'm a pipe designer, and used to be a fitter. We have hung some heavy stuff from pipe in the field. It'll be fine. You aren't building a roll cage from home depot **** pipe. It's a hot rod, not a Space Shuttle.
I think tubing would be the way to go. If the whole structure was schedule 80, it would be no problem. However you have the frame rails which are probably .125" thick and a perch that's .500" thick all being welded to a crossmember .250" thick. That's an extremely critical weld that's going to require a lot of prep to get that heavy pipe mated to the relatively thin frame pieces. Having a lot of heat in one localized place can make the surrounding areas more brittle. And you're going to need a lot of heat to penetrate the cross member and perch.
Guess that's closer than I thought. I was more concerned about welding the .500" thick perch to the .218" wall pipe. I've got a 220 Hobart MIG welder and I wouldn't be comfortable welding that perch, its too thick. I think it would be best to consult a professional on this one.
as far as surface finish goes both sch. 40 and sch.80 are available in '' black iron '' which is a coated finish like a varnish which in normal weld prep you would remove anyway and in ''bare pipe'' which is no permanent coating except shipping oil.....the bare pipe is much nicer to work with......... .02
This is covered in Welding 101. Seriously, if welding 2 different thickness material together, without fear of failure, is a problem, yes, you really should have a professional do your welding. (we need the work )
Yeah I know, I'm three cl***es (all math) away from an ***oc. degree in welding engineering technology. I was just wondering how this guy was planning on tackling the welds on some pretty thick material? Guess I was trying to say I have a pretty nice, powerfull 220 MIG welder and I wouldn't think of welding 1/2" material with it. I really hope he wasn't headed out to the garage with a Home Depot 110 buzz box
sounds good to me the only other thing i can think of is to run the half inch plate threw the pipe so it gives it more strangth i did it with my truck and its perfict you run it strait threw and weld it on molth sides just a idea so their is no chance of a weld breaking
When did any steel become brittle? We are not talking about cast iron sewer pipe here. If steel was brittle we wouldn't have those beautiful fat fenders with their lovely rounded and stretched forms. Fenders would crack like fibergl*** instead of denting in an accident. That is one of the best features of steel. We can heat it beat the **** out of it bend it every which way, weld little pieces into big pieces and it's still stronger than ****. If you are scared of crashing have a certified welder build it for you. Don't ask him to weld up your joints. He will want to have properly prepared joints so that he can give you 100% penetration. CYA on his part.
I believe he was speaking about hydrogen embrittlement. It's what happens to metal that is over heated during welding. Too much hydrogen will crystalize the steel and cause it to become more brittle, which can crack. Hammering sheet metal doesn't create enough heat for it to happen. Getting back to the pipe thing. Yes #80 is strong, way better than #40 (heavier=stronger) and can be used for a lot of items but there are a lot of dynamic forces in a car that don't exist in a building or other stationary structure. That's why tubing is the choice of ch***is builders. It is manufactured for this use. Burst pressure means nothing by the way. I can run pressure through a hose but wouldn't use it for ch***is tubing. You can use a lighter piece of tubing and get the proper strength required. And through proper welding and ch***is design it will be good. Or you could use a ton of heavy steel and hope it will hold up out of shear m***. I'm not saying it won't stay together, it probably will. I'm just saying it can be done smarter and lighter and better with piece of mind that it won't fail instead of hoping it will "probably" stay together. We can argue about that all day but after all of the talk I don't have to do 75 mph in it, the owner does. And the guy he sells it to a few years down the road. Is it worth gambling you life on? Or someone elses? To save $20.
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