Minimum Weld Seam Separation on Pipe

Date 03-18-2015 15:12

We have been discussing this for quite some time in the shop and thought it was time to get a actual answer. We would like to know what the minimum weld seam separation for pipe is under API 1104, ASME IV and AWS D1.1. I began to look through our code books, which are all out of date, and found the Girth Weld Alignment 5.22.3.1 in AWS D1.1 but have yet to find anything mentioning weld seams and where they should be placed. To give you a idea of what we are doing, we have a machine we are testing called a Pipeline Inserter which pushes pipe into tunnels or open trench pipelines and it is set up for 30" pipe currently. The pipe is 30" x0.50 X70M with the Dura-Bond DSAW coating. We are welding this pipe to put inside the machine for testing purposes and not to a code weld (although our AWS D.1. certs cover this weld) and was wondering what the actual code(s) says. Any help would be appreciated and if I stumble upon my own answer I will post it up.
-Jonathan

By welderbrent (*****)

Date 03-18-2015 15:31 Edited 03-18-2015 15:35

Okay, I think what you are asking is 'how far apart at a minimum must two separate weld joints be?' So, you have two circumferential welds on 30" X .500 wall pipe and need to know how far apart the applicable code says they must be spaced? Right?

First, if the engineer, or manufacturer/owner on the project, has accepted D1.1 welder qualifications, even a welder qualified to a plate test would be qualified. Anything over 24" can be qualified by plate.

Now, vague as my memory is on things API and ASME I believe that this question has arisen many times on the forum and could probably be found using the 'search' function. But, I'm sure some of the pipe guys will be along to correct me if I misspeak my opinion of your query.

As I recall the discussions, and as far as D1.1 goes, there is nothing in the codes that dictate a set distance nor formula to determine distance between joints.

While there may be practical and even metallurgical reasons for such separation, it is a question left to the specific engineers on the job to determine if they want any particular space between joints.

As with many other issues, there are wives tales and rules of thumb abounding on what the spacing should be. I believe in this case it is normally considered to be a multiple of the diameter of the pipe, either 1 1/2 X or 2 1/2 X , again from my poor memory. So with your 30" pipe it would be between 45" and 75" for a MINIMUM according to a rule of thumb. But, rules of thumb have no bearing in codes. It is either in the code or it is not. As far as I know, especially for D1.1, it is NOT.

The other perspective that you could be referring to is how to align the seam welds for offset from one section to the next so that they are not in line which would lend itself to an extended inline weakness. I don't believe that is in the codes either. Again, there are rules of thumb and standard practices by some companies but nothing called out in the codes. You will often see 1/3 offsets. Sometimes other ratios. But nothing code wise as far as I recall.

He Is In Control, Have a Great Day, Brent

By Superiorwelding (*)

Date 03-18-2015 15:56

Brent,
I am in fact referring to the seam weld on the pipe. We had heard pipelines use the 10 and 2 rule so if one of the seams burst the pressure won't push the pipe out of the ground. The pipeliner said mainly this is the way it's been done and might not be a code thing. He also said spiral wound pipe it doesn't matter where you put the weld, lol.
-Jonathan

By welderbrent (*****)

Date 03-18-2015 16:10

As I recall even spiral you don't want the seams 'lined up'. Creates the same scenario.

Yes, offset is good. But as to a specific amount in degrees, percentage of diameter, etc. I don't think you will find one mandated by the codes.

Brent

By Superiorwelding (*)

Date 03-18-2015 16:50

I guess that was a joke gone bad. I meant the seams along the pipe and not where they meet at the ends of the pipe. Oh well, better luck next time. :lol:

Thanks for your responses Brent.
-Jonathan

By welderbrent (*****)

Date 03-18-2015 17:30

OK, sorry I messed up your moment of humor, a little slow today. I had a long day yesterday; Prescott, to Flagstaff, to Phoenix, back to Prescott. And that doesn't count the inspections time and teaching time.

Better luck next time. :lol:

Brent

By jarsanb (***)

Date 03-18-2015 19:46

Regarding the publications you've listed, I doubt you will fing any info. If there is such a requirement it is usually in the owners QC. Offsets of 1/4 diameter are common. No seam on the bottom quarter due to that is where any oil/sludge from compression processes can cause internal corrosion is a common requirement. ASME IV - Low pressure Heating boilers, were you thinking of VIII?

By Superiorwelding (*)

Date 03-19-2015 11:11

Thanks for pointing that out. I mean ASME IX and not ASME IV, my mistake. The oil/sludge causing corrosion is a interesting one.
-Jonathan

By ctacker (****)

Date 03-19-2015 04:23 Edited 03-19-2015 04:25

D1.1 (2010) 5.22.3.1, also says longitudinal weld seams shall be staggered at least 90°, unless closer spacing is agreed upon by the owner and fabricator.
I seem to nail pile drivers all the time on that one.

By Superiorwelding (*)

Date 03-19-2015 11:12

ctacker,
Thank you!! It was right in front of my face and I didn't see it!
-Jonathan