Shop Floor Talk  

Go Back   Shop Floor Talk > Welding and Metalworking Forums > Welding

SFT Search:   
Reply
 
Thread Tools Display Modes
  #1  
Old 03-22-2009, 07:52 PM
Dark_Angel Dark_Angel is offline
Member
 
Join Date: Mar 2008
Location: Ashley, North Dakota
Posts: 69
Send a message via MSN to Dark_Angel Send a message via Yahoo to Dark_Angel
Default Pipe Welding question.

Alright, well I was having a discussion with a friend who is currently going to the same college I went to and he started asking me some questions about pipe welding since that is what he is focusing on. Well he asked what to do if you burn through on the cover pass. I told him that he should stop and clean it best he can and weld it up.

It then dawned on me that I had this same exact thing happen to me last week while I was doing a welding job for a new building that is going up. So now I am wondering was that the best advice to give because that's all I could think of to tell him. Now I have my own questions.

With this job I am currently doing I am welding up 3" Sch. 40 carbon steel pipe 6010 root and 7018 hot and cap pass. There is only about 5lbs of pressure going through them but will be testing them around 60-100lbs of pressure. I am just wondering with that mistake I made will that cause any problems if I cleaned it up well and welded it back up?

Also if my root isn't 100% will a good hot pass and cover pass keep the weld from failing?
The reason I ask that is I am using a welder that isn't necessarily up to par but I make due with it pretty well except sometimes I have problems welding up my root pass.

Thanks for all your help, much appreciated!
Reply With Quote
  #2  
Old 03-22-2009, 08:25 PM
journyman's Avatar
journyman journyman is offline
Senior Member
 
Join Date: Apr 2007
Location: Hillsborough NH
Posts: 708
Default

If your burning through on your cover pass, you may want to check all of your parameters, amperage, speed of travel, lead and work angles. If that happens again try to remember what you were doing in order to correct the problem. As for the repair, I would treat it like the root pass. Grind/feather the weld down on both sides of the hole. Light up with 5P and make the repair. As far as passing the pneumatic test and operational load it will be as good as any other weld you made on the system, assuming you are consistent in your work. If it were being x-rayed to b31-3 you could have some trouble as the hole likely occurred in a spot that you are not comfortable welding in; i.e., some were between 3 and 6 o'clock I'm guessing. But if you grind back far enough there is no reason why you couldn't put a passable root in. Hope this of some help.
__________________
Neo-con: another name for moderate democrat
Reply With Quote
  #3  
Old 03-22-2009, 09:04 PM
Lu47Dan's Avatar
Lu47Dan Lu47Dan is offline
Connoisseur of Old Iron
 
Join Date: Mar 2006
Location: N/W Pa.
Posts: 5,972
Default

+ 1
I will also add I have done repairs to the root pass that did not show up as anything but a good root on the x-rays . Dan
__________________
Tools to Men are like Shoes to Women , you can never have too many !!
Used diesel engines are an adventure anyway you look at them !!
Miller XMT-304 Multiprocess
Miller 10-E Wire Feeder
Miller Spectrum 2050 Plasma Cutter
Hobart AC/DC stick welder
Hobart 175 Mig
Craftsman O/A set
Turbo torch and B-tank
Reply With Quote
  #4  
Old 03-22-2009, 09:19 PM
Dark_Angel Dark_Angel is offline
Member
 
Join Date: Mar 2008
Location: Ashley, North Dakota
Posts: 69
Send a message via MSN to Dark_Angel Send a message via Yahoo to Dark_Angel
Default

Well I burnt through it once because I was on the scissor lift at the time so I had someone down below adjust it to what I asked but he turned it up a little higher than I would like. The way they are going to be tested is we are just capping one end of the pipe and putting air to the other and are going to spray the weld with soupy water and look for bubbles.

I was just curious that if I had a problem with the root would a good hot and cover be sufficient enough to pass this pressure testing?

I don't think there is any problem with my roots but I am paranoid like that since I am pretty new to the welding world just got out of college last may and I wanna make a name for myself. When I grind out the root pass there is no holes or pinholes, same with the hot pass, I make sure when I am welding the root everything is clean etc, and that the majority of the sparks are inside the pipe like I was taught.
Reply With Quote
  #5  
Old 03-22-2009, 10:18 PM
Jim-TX's Avatar
Jim-TX Jim-TX is offline
Chairman of the Headboard
 
Join Date: Oct 2006
Location: Abilene, TX
Posts: 2,412
Default

I'm not a pipeline welder, but if they are only testing with soapy water I don't think that you have anything to worry about.
__________________
Jim
Reply With Quote
  #6  
Old 03-22-2009, 10:57 PM
Blackdog's Avatar
Blackdog Blackdog is offline
Senior Member
 
Join Date: Oct 2005
Location: The Frozen Arctic
Posts: 453
Default

A good root will make fill and cap easier. As everyone else has said make sure to feather out the repair. With no X-ray involved you will be fine. I have always treated the cap as the final presentation of the welding skill, but I have seen some butt-ugly ones that have passed.
__________________
Always one more job, but where?
Reply With Quote
  #7  
Old 03-22-2009, 11:18 PM
Dark_Angel Dark_Angel is offline
Member
 
Join Date: Mar 2008
Location: Ashley, North Dakota
Posts: 69
Send a message via MSN to Dark_Angel Send a message via Yahoo to Dark_Angel
Default

Alright so since the welds are only being tested with soupy water and nothing like an x-ray and I know I have a decent root, hot, and cap I have nothing to worry about...Great But if my root does have a defect that I could not notice I should still be okay with good hot and cap pass? Sorry if I seem annoying about this but testing day is drawing nearer and like I said....a little paranoid because I want to get my name out there.
Reply With Quote
  #8  
Old 03-23-2009, 12:11 AM
Blackdog's Avatar
Blackdog Blackdog is offline
Senior Member
 
Join Date: Oct 2005
Location: The Frozen Arctic
Posts: 453
Default

Practise, practise and more.....p
Watch your stop/starts, work the sides and avoid the wagon tracks, the slag in the corner will do you in everytime and more .............practise. Get comfortable with your heat and speed. Remeber that there are machines that do this and you are better than that.

a good weldor is a lousy grinder
a good grinder is a lousy weldor
__________________
Always one more job, but where?
Reply With Quote
  #9  
Old 03-23-2009, 09:43 AM
Lu47Dan's Avatar
Lu47Dan Lu47Dan is offline
Connoisseur of Old Iron
 
Join Date: Mar 2006
Location: N/W Pa.
Posts: 5,972
Default

Leaks are part of the job , anyone out there doing pipe welding has had one . If they say they have never had a leak , they are not being honest about it . I have had three over the years and a couple of bad x-ray tests , but worrying about them tends to make you have more not less . Welding is a job where the welder needs to be comfortable with his abilities and with his surroundings . I know rad room welders who won't weld outside the nuke plants . I am a welder who does not want to weld in the nuke plants , not that my skills are lesser them the guy's that do that welding , I just couldn't stand the snail's pace of production .
Worrying about whether or not you will have a leak is the surest way to have one . Relax , let your technique and skills work for you . Best piece of advise I ever received was to relax and enjoy myself , if you can't , then maybe it is time to find another profession . I had many jobs before becoming a Steamfitter , and hated most of them , doing plumbing and pipefitting is a job I really enjoy doing it not only exercises the body but the mind also . Working around people who hate their jobs was a learning experience on how not to go through life .
I know that the original question was if the hot pass , fill and cap will make up for a shaky root , they can and sometimes do . But if your roots are all good , they make life a lot easier .
Just my two cents (U.S.) Dan
__________________
Tools to Men are like Shoes to Women , you can never have too many !!
Used diesel engines are an adventure anyway you look at them !!
Miller XMT-304 Multiprocess
Miller 10-E Wire Feeder
Miller Spectrum 2050 Plasma Cutter
Hobart AC/DC stick welder
Hobart 175 Mig
Craftsman O/A set
Turbo torch and B-tank
Reply With Quote
  #10  
Old 03-23-2009, 11:23 AM
cramd's Avatar
cramd cramd is offline
Drivin' Fool
 
Join Date: Nov 2008
Location: Yorkton, Saskatchewan,Canada
Posts: 4,333
Default

Quote:
Originally Posted by Dark_Angel View Post
The way they are going to be tested is we are just capping one end of the pipe and putting air to the other and are going to spray the weld with soupy water and look for bubbles.
I am not a fan of using "soapy water" to test for leaks in a pipe joint or bad fitting.
I worked in a natural gas utility for 36 years, and part of my job was locating leaks -some in piping at 100+ PSI of pressure,some down as low as 4 OZ of pressure.I have found leaks using electronic leak detection equipment and confirmed with a good quality leak detection fluid (LeakTec), that were impossible to relocate when the plumber hired to fix the leak tried to find it using a soapy solution.Most of these home grown solutions are made using a weak dish soap/water mix,and aren't really thick enough,or clingy enough to stay on the pipe long enough to form bubbles,especially on a really small leak.
I have also seen leaks on natural gas transmission lines with the pressure dropped to 100 PSI, and even good leak detection fluid had to be in place several minutes before the most minute bubbles began to form.
A better solution would be to pump up the system to the test pressure with a good quality pressure gauge attached, then lock in the pressure,mark the gauge and wait 20 minutes or so to see if the pressure drops.If it doesn't drop, no need to piddle around with soapy water.
My $.02 worth.
Dave
__________________
Miller Thunderbolt XL AC/DC
Hobart Handler 190
Angle grinders,14" chop saw,Hobart medium duty O/A set
Some air tools,fair selection of hand tools,and other "stuff"
____________________________________________

The difference between genius and stupidity, is that genius has limits. Albert Einstein
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Web Search:

All times are GMT -5. The time now is 07:13 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2019, vBulletin Solutions Inc.