The whole scoop on root gaps

[Blackbird455]

Can anyone tell me the big picture on root gaps?

Is there a formula? What are the rules?

[JTMcC]

The big picture is this:

If you intend to make your living welding pipe, you will have to deal with all kinds of space from slammed shut to big enough to throw a dead cat thru.

When that becomes routine you're ready for the workforce.

JTMcC.

[FATFAB]

Can anyone tell me the big picture on root gaps?

Is there a formula? What are the rules?

The big picture??? Hmmm?


Well when working to a procedure developed by someone other than you it is decided for you and is detailed in the procedure. I am guessing you know this?

A formula or rules. What ever works.

If you are developing your own procedure then you will be testing (destructively) who well you choose.

Are we asking "open roots" roots with no backing, no back side welding, (pipe) then a common saying is a nickels (thickness) gap and a dimes (thickness) land.
If you are talking about a CJP groove weld (not following ASW prequalified procedure) with backing then I will set it up with enough gap for me to easily tie all three base materials together in one root pass. That dimension then is dependent on the process to be used.




Like a lot of things with welding (and life) absolutes are ill fitting in many instances.

I think you might get better answers with a more definitive question.

What is the reason for the question? How are you going to apply the answer? Is this for general information or do you have a particular project in mind?

[hogan]

It is best to follow a WPS with all that info listed in it. Otherwise search for prequalified WPS'.

[Blackbird455]

Yeah I never said anything about welding for a living, or anything about throwing dead cats through anything. I understand that in critical applications, the proper root gap is necessary to prevent internal stress and catastrophic weld failure. All I am trying to do is get answers from people that actually know, not metaphores. And I also know that there are people called "pipe fitters". But you are missing my point, which is, I want to know how the gap is determined, what factors are considered, and what regulations govern it. I do not, nor do I intend to weld pipe for a living, so I am hoping that there is someone that does, that may be able to point me in the right direction. If you don't know, it's ok, and you don't even have to respond.

[SundownIII]

JT,

Don't you just love it. Newbe comes on looking for the "big picture" regarding gaps.

Guy who's been welding pipe for decades gives it to him "down and dirty". The way things really are.

Newbe comes back with sarcastic response.

Really makes one want to take the time to respond.

Guess we've become a society that likes to be "spoon fed" or can't take suggestions if they're not "sugar coated".

Oh Well, on to the next poster.

[JTMcC]

Yeah I never said anything about welding for a living, or anything about throwing dead cats through anything. I understand that in critical applications, the proper root gap is necessary to prevent internal stress and catastrophic weld failure. All I am trying to do is get answers from people that actually know, not metaphores. And I also know that there are people called "pipe fitters". But you are missing my point, which is, I want to know how the gap is determined, what factors are considered, and what regulations govern it. I do not, nor do I intend to weld pipe for a living, so I am hoping that there is someone that does, that may be able to point me in the right direction. If you don't know, it's ok, and you don't even have to respond.



Wow, you really showed me.

I hope someone who knows how to weld pipe comes along to answer your question the way you want them to.

I'll take your sage advise and not comment on things I don't know about.

JTMcC.

[migwelder05]

Wow, you really showed me.

I hope someone who knows how to weld pipe comes along to answer your question the way you want them to.

I'll take your sage advise and not comment on things I don't know about.

JTMcC.

yeah because you wouldn't happen to own a pipe welding company.
http://www.firstratefabricators.com/home

[Broccoli1]

Can anyone tell me the big picture on root gaps?

Is there a formula? What are the rules?

http://books.google.com/books?id=zeRiW7en7HAC&pg=PA124&lpg=PA124&dq=Pipe+welding+root+gaps&source=web&ots=fQmamiKcYi&sig=UuYqDjZZmOSyvfXXX_zN91RySSs&hl=en&sa=X&oi=book_result&resnum=5&ct=result#PPP1,M1

[FATFAB]

Yeah I never said anything about welding for a living, or anything about throwing dead cats through anything. I understand that in critical applications, the proper root gap is necessary to prevent internal stress and catastrophic weld failure. All I am trying to do is get answers from people that actually know, not metaphores. And I also know that there are people called "pipe fitters". But you are missing my point, which is, I want to know how the gap is determined, what factors are considered, and what regulations govern it. I do not, nor do I intend to weld pipe for a living, so I am hoping that there is someone that does, that may be able to point me in the right direction. If you don't know, it's ok, and you don't even have to respond.

Wow

"Missing your point" you received several answers"



"If you intend to make your living welding pipe, you will have to deal with all kinds of space from slammed shut to big enough to throw a dead cat thru.

When that becomes routine you're ready for the workforce."


"It is best to follow a WPS"


"A formula or rules. What ever works."

"Are we asking "open roots" roots with no backing, no back side welding, (pipe) then a common saying is a nickels (thickness) gap and a dimes (thickness) land.
If you are talking about a CJP groove weld (not following ASW prequalified procedure) with backing then I will set it up with enough gap for me to easily tie all three base materials together in one root pass. That dimension then is dependent on the process to be used."
{I hate quoting my self**




So what are you talking about?

[ocweld]

hi fatfab i see you are still school the new one on gaps . my rule on gaps is just fill it and gether done.

[Broccoli1]

probably something like this:

"Joint DesignAgain, regardless of the material to be welded, there are a few general practices that should be consideredwhen designing the weld joints.Plate 3/16 in., (4.8mm) thick or less may be butt welded with square edges using the short arc process or alow current spray arc (aluminum) if a root gap of 0 to 1/32 in. (0.8mm) is maintained. Plate thicknesses of 3/16 in., (4.8mm) and 1/4 in. (6.4mm) may be square butt welded with the spray arc process when a 1/32 to 3/32 in. (0.8-2.4mm) root gap is used. In all cases, a single pass can be used if a permanent or temporary backup bar is used. When welding in the overhead position, it is usual practice to always butt weld using a backup bar. However, if a backup of any kind is not used for 1/8 in. (3.2mm) thick plate and above, twopasses are usually necessary – one from each side. A bead overlap greater than the original root gap is desired to prevent centerline porosity and poor fusion. Maximum overlap is attainable if the backhand technique is used on the second side.Plates 1/4 in. (6.4mm) thick and thicker generally require single or double Vee grooves with 45 deg. to 70deg. included angles (depending on base material and thickness) to produce quality welds. A 0 to 1/16 in.(1.6mm) root face with a 1/32 in. (0.8mm) root opening is used. In single Vee grooves where no backup isused, a sealing pass from the back side will generally be required."

http://www.esabna.com/EUWeb/MIG_handbook/592mig8_4.htm


but I still suggest a book to have on the desk for reference.:)

[Blackbird455]

Just the basics, thats all I am looking for, not an argument. And yes compared to some of you , I am a newbie, thats why I am posting on this board, looking to more experienced welders for advice and direction. Sadly this thread has degraded, much like alot of others, and it looks like the usual suspects, that aren't even contributing to the subject matter of the thread.

Thank you Broc for the link, I haven't seen that one yet, I'll have to add it to the stack with the rest of the books.

Does anyone else have anything helpful to say?

[Blackbird455]

See thats what I was looking for, thats good stuff!!

[FusionKing]

See thats what I was looking for, thats good stuff!!

Yup Broc has a knack for finding good info that's for sure!!

[FATFAB]

Just the basics, thats all I am looking for, not an argument. And yes compared to some of you , I am a newbie, thats why I am posting on this board, looking to more experienced welders for advice and direction. Sadly this thread has degraded, much like alot of others, and it looks like the usual suspects, that aren't even contributing to the subject matter of the thread.

Thank you Broc for the link, I haven't seen that one yet, I'll have to add it to the stack with the rest of the books.

Does anyone else have anything helpful to say?

Sadly you posted an open, indirect, ill thought out question. Then complained that you were not getting what you want. WAAAAH!

I'll be sure to add you to the ignore list, sub heading helpless hapless hopeless.

[JTMcC]

[QUOTE=FATFAB;161507]Sadly you posted an open, indirect, ill thought out question. Then complained that you were not getting what you want. WAAAAH!

I'll be sure to add you to the ignore list, sub heading helpless hapless hopeless.[/QUOTE




Yea, he just ask the question in the wrong way. He didn't really want the "whole scoop on root gaps". What he wanted was a link to a book.

Maybe next time ask for the "link to a book" and save us all a lot of trouble trying to actually give you what you ask for.

A book will give you the whole scoop on root gaps about as well as a book will give you the whole scoop on ***. (s-e-x)

JTMcC.

[snowbro]

Yeah I never said anything about welding for a living, or anything about throwing dead cats through anything. I understand that in critical applications, the proper root gap is necessary to prevent internal stress and catastrophic weld failure. All I am trying to do is get answers from people that actually know, not metaphores. And I also know that there are people called "pipe fitters". But you are missing my point, which is, I want to know how the gap is determined, what factors are considered, and what regulations govern it. I do not, nor do I intend to weld pipe for a living, so I am hoping that there is someone that does, that may be able to point me in the right direction. If you don't know, it's ok, and you don't even have to respond.

i haven't really welded all that much pipe.. I'm actually a Union Millwright, but I just passed my 6G High Pressure, so I'm now a Permit Pipefitter/Welder, out of Sault Ste Marie Ont.

Anyways, over the past week of practicing I asked the same questions you did, and the answer i basically got was, if you are using 3/32 rod, then that's what your gap should be ( I like it, alittle tighter). But rule of thumb anyways. I'm pretty sure landing is the same, or abit less. But I like 3/32, if not abit more. So this would also apply if you were running 1/8 rod, and so on. I could be dead wrong here, but this is just what I know from practicing for the last week.

If I was you, I'd just get some pipe, go with what I just said, and then you'll know what you like.

Matt

[Green MT Welder]

I may be over stepping my bounds but i thought this forum was too share info ,advice and ideas. not take shots at someone for asking a question. where i come from the only stupid question is the one that wasn't asked. but that's just my two cent's

[tinkitten]

The forum is a good place to get help, but you need to do a minimal amount of research first!

Anyone with enough information to respond to your inquiry has spent a lot of hard work and experience getting it, and they expect that you will too. If you ask a question that reveals you haven't so much as cracked a book about it, you can expect to get some crap from the folks who have the advice you want.

Once you read about a topic in general, and still have specific questions that the book doesn't answer, then you have resources like this forum. Enjoy.

[Smactek]

And I Thank the Stars (and Andy & Miller) That there is a place like this Where people take their own free time to read and post to so many of us that ARE NOT IN The KNOW! Besides IMHO I've found I retain information for a much longer period when it was a little Tuff or Gruff to learn. :cool: