butt welds

[willieworld]

ive been watching some of the builds on landracing and other sites and i dont like some things that i see---butt welds in structural areas arent safe-----im going to show everyone a good safe way to join tube together ---there are many ways to do this but this is an easy way and only requires a drill ----a good rule of thumb is to make the length of the inside  sleeve at least 4 times the dia. ---the inside tube that i used is 1 1/4  o. d.--the length is 6 inches --drill 3 holes through the outside tubes  (through both sides )  i like 1/4 inch holes---slide the tubes together and weld---weld the rosettes first and make sure you weld to the inside tube ---then weld up the butt ---some racing bodies dont allow grinding of the welds so check with yours before you do --------------------------
i posted this under willies builds but decided to repost it here     willie buchta

[Geo]

Willie,

Thanks for taking the time to make an example, post and explain the process.

I'm about 1/2 a bottle away from welding on the car.  One thing I noticed, as a log ago welder relearning and using a bigger mig than I had years ago is that I am slowly turning up the amps and feed rate.  I am trying to reach the point of good penetration by looking at the back side of the practice pieces of 1 5/8 roll bar tubing.  I tried a friends smaller welder the other day and noticed it did not have the power needed.  I am moving to the point of melting the back side / hidden / interior part of the tubing.

Your thoughts of how far to go.  For example do I need to worry about melting the bottom of a vertical tube and having it sag?  I can send a pic in the next few days of the backside of my practice tubing.

Thanks again,

Geo

[HotRodV8]

Willie - -

Thanks for moving this post from the Willie's Build site because I could "read only" there.

I think your butt weld example is a great tip for all welders. Your pictures were very clear and easy to see what you did. I haven't welded for 40 years, but I plan to do some in the near future on a build. I also liked your tip about Holes on another post.

I think you should do a Willie's Tip of The Month on shop safety, welding or basic metal construction. I sure could use the reminders and I'd probably learn something new too.

Thanks,

Bill,  past welder and brazer            

[jimmy six]

I do not agree with Willie's statement.

If butt welds aren't good then every power plant in the world with a steam boiler wouldn't Willie's acceptance.

I've been working in them for over 43 years and was the supervisor over boiler mechanics and certified welder for a considerable time. We welded in "pups" for 100's of tubing leaks and all were x-rayed. The minimum pressure I supervised was 2000 and the max 3600  I have no trouble with a proper butt weld....JD

[SPARKY]

With any welding and especially MIG you have to have a good consistant width heat track on the back side of what you are welding or you are not getting enough heat.--- with TIG I was taught  that you want an ocasional back sag or puddle

[donpearsall]

Jimmy Six, your Steam Plant example does not relate to a roll cage. Steam tubing is not structural and carries almost no load except for its own weight. A roll cage must withstand the forces of being rolled and crashed. Willie's joint weld example is many times stronger than the tube itself and there is nothing wrong with that.

Don

[interested bystander]

Yrs truly knows of no motoracing association that, if it's referred to, doesn't require "visual reinforcement of butt welds" or words to that effect.

Conainment of pressure is a mite bit different than dealing with tension, compression and bending loads.

Just do what Willie says!

[wobblywalrus]

In my youth I got a job in a gold mine.  I welded all sorts of scrap metal together to make chutes, bins, conveyor arms, etc.  I used whatever rod I could find.  The finished job looked a treat.  The owner showed up and the foreman and I dumped the first load of rock in the hopper and let it run down through the line.  A bunch of my beautiful butt welds snapped and everything went to pieces.  A check was written, handed to me, and I was told to go.  The only job I have been fired from.

Butt welds are successfully used in the manufacturing world.  They do structural designs to make sure the welds are not overloaded.  They know the composition and temper of the steel they are using and the makeup of the rod.  Samples are welded and tested in the lab.  Certified welders do the work.  There is quality control such as x-rays.  I did not do this at the gold mine and most home builders do not either.

Willie is right.  Inserts and gusset plates are extra work but they can save a person's hide, especially with our seat of the pants design and engineering.   

[Beairsto Racing]

Willie,

I hope you will return to posting your build diaries. I enjoyed them, learned lots and I'm sure others did too.

-Scott

[jimmy six]

DonP. I still do not agree. All of our welders made "coupons" which were made buy doing a butt weld on tubing, then sectioning the tubing, pressing a "U" in it to test its integrity All of our welders were tested in this manner yearly no failures were acceptable. Eventho boiler tubing is not structural I would trust and DID trust one of my welders to do work on my cage. Granted there are no places where it was tube to tube in a straight line but I would still trust one to make that type of weld.

Willies example is a good one and is a very good way of welding straight line tubes and definitely useful in long tubing built frames. I believe reputable chassis builders use the method described. My point is not to make blanket statement.

[Peter Jack]

Jimmy Six, I am a licensed weldor. By the way a weldor uses a welder to create the weld.

When a tube is welded with a straight butt weld it automatically creates a stress riser right beside the weld assuming proper penetration and reinforcement. The proper weld will easily pass any x-ray or pressure test. If the tube is dynamically loaded the tube will fatigue right beside the weld unless there is further reinforcement. The inside sleeve with the rosette welds is the standard reinforcement for that type of weld and I can assure you that I wouldn't use any tube chassis that included butt welds, either straight or angled, without the required reinforcement.

Pete

[jimmy six]

Peter. Aggreed, and I stand corrected on the spelling (I knew better). My response had to do with a blanket statement.

As I stated every weldor who I supervised in high pressure welding had made the coupons I related to which were put under a 180 degree press and could not or did not fail.

99% of the Z-ed rear ends on framed cars have butt welds and no re-inforcements. Granted they are not round tubing and I would use the proper re-inforcing for a round tube "splice".  I just don't like blanket statements.

There are many excellant frame people who ave built LSR vehicles and in incidents held up to prtect the drive from harm and I hope it stays that way..... I'll stop....JD

[ScottG]

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[ScottG]

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[Gwillard]

The method Willie posted is the best for our applications. Butt welds are acceptable in piping where the major concern is hoop stress and the loads are predictable and controllable. On a race car the major concern is in bending which would place the HAZ under compression and tension. Since the HAZ is the weakest part of the weld, and we don't want to decrease the overall integrity of the structure, a reinforced splice is best for the type of joint discussed. This moves the stresses to an area better suited to handle them.
Both AWS and ASME refer to the operator of the welding equipment as a "welder". The power source is also generally referred to as a "welder". I've only seen "weldor" used a couple times including here.
Willie did a great job with the pics and description. The only things I would add are to remove all mill scale, rust, etc, from the areas to be welded and, if welding 4130, use a preheat and don't be afraid to put some heat into the weld to slow down the cooling rate. When welding 4130 heat is our friend.