American Welding Society Forum
I try and keep this brief..if that is possible. Was helping a guy at the school I went to last night try and prep for a 6g on carbon steel. 6010 root, 7018 fill and cap, 3" sch. 40 pipe. From what I understand, as it was explained to me it is for ammonia benzene(?) in a factory/plant of some sort. Anyhow, he had a printout of the, well, it was a printout from the hr guy that basically said, "how to weld a 6g" something I think I would find searching on Google. So, the fella was asking about the root, fill, cap etc., but kept saying that the hr dude kept telling him he wanted heavy penetration on the root. I had to ask to try and clarify what he meant exactly as far as "heavy penetration" and he showed me a youtube vid that had about a 1/8" ring hanging on the inside of the pipe or maybe 3/16", seemed pretty large, but then again I really don't know. From reading on here and talking with you folks I always here that they don't want excessive penetration due to corrosion, disturbances in the flow of the fluid/gas in the pipe and so on.
I showed him how I run an uphill root, fill, cap and had a nice little 1/16 high ring on the inside, tied in both sides of the pipe but then we got back on the subject of the "Goodyear" weld that they say he needs on the inside. Seems like the teacher up there knows of this guy on this job that is hiring and neither of us have seen procedures laying out what the engineer wants in order to help this guy out. So I spent the evening helping this welder out, running passes, watching him run passes and so on but the whole night I was stuck on the "heavy penetration" issue.
So, I guess one question that would be on my mind would be is there something that would be considered excessive penetration on a root pass as far as the depth in which the weld protrudes into the center of the pipe? I know one cwi I talked to said that if you had a consistant weld all around and then one stalactite/stalagmite hanging down or up at one point he said then they would consider that "excessive". So when I talked to him I basically said, "if you had a 1/4" ring on the inside of the pipe but it was consistant then that would be considered good?". I know 1/4" is huge but just trying to figure this ASME thing out and thinking there has to be some sort of criteria right??? Or would the criteria be laid out by the weld engineer, CWI etc? Even if it was laid out by them I would imagine there was some sort of criteria to guide them, not just something pulled out of a hat.
That's all I can think of for now, but looking for input on this. I'm trying to become more educated in the ASME.
ASME B31.1 Power Piping gives no specific dimensional tolerance for excessive root penetration. However when a weld is to receive RT you must refer to 127.4.2 C5 that addresses the condition of a weld root where if there is an abrupt density change it must be corrected.
Refer to acceptance criteria for a visual examination and for radiography in 136.4.2 and 136.4.5, respectively.
Basically the Code(s) state that there shall be full penetration. Really anything beyond full penetration at the weld root provides no benefit and can be harmful in certain fluid and high pressure steam applications.
My 20+ yrs of experience with Weyerhaeuser Paper Company recovery boilers, is that their mill specifications call out for internal root reinforcement to be 0"-1/16". Superheat tubes spec out at no more than 1/32" internal reinforcement. No suck back is allowed. Also any piping that falls under ASME Section I, VIII, B31.1 are to be GTAW roots.
Pipe welding in the refineries in Baytown, TX in the '70s, we were allowed up to 1/8" root penetration as long as the root thickness was uniform. As a welder yourself you know how tacks go in heavier than the rest of the root weld so I was also mindful to place the tacks a bit more on the light side as to give the remainder a consistent thickness.
Therefore the acceptance critera is usually specified by the Client or Owner who takes into consideration the application and design of the system.
Thanks for that Robert, great explanation!
You're most welcome Shawn.
You said the piping was going to be for an ammonia benzene system? Sounds like is could be part of a coke producing plant. The process of making coke, one of the necessary components in forging steel, produces smoke that contains high amounts ammonia and benzene, a known carcinogen. The piping system takes the smoke to an "exhauster", or several of them, for containment to treat before releasing to the atmosphere. So this is very important piping your friend will be fabricating & welding.
With the piping just transporting smoke, IMHO I don't see where the requirement for a "heavy penetration" justifies itself. Of course I am neither PE nor Owner of the plant. As an inspector tho I would want to examine the AFC dwgs for weld symbols, mill specs and general welding notes.
On another note, I grew up near you in the town of Fort Payne, Alabama. Tenessee is such a beautiful state, God's country. Having lived in Oregon for the past 20yrs tho I just can't take the humidity of the South unfortunately. I visit relatives back there and in Gadsden, AL during the winter months. :)
I grew up near Fyffe, AL myself. Been through Fort Payne and Gadsden many times. It's a small world we live in.
Small world indeed. My previous employer in Houston had a plant in Gadsden. I like the area very much. Back then I was flying through Birmingham about once every two weeks or so. The Logans in Gadsden makes the best Road House Teas in the entire chain. Not for the young.
ASME B31.3 Table 341.3.2 gives the Acceptance Criteria for Welds, including internal protrusion.
I'm certain that the issue in the original post has been resolved for quite some time now, however this response is for the benefit of whomever may stumble upon this tread looking for this same answer, as I did.
And for performance qualification using ASME IX only, there is no amount of reinforcement restricted or required. Since 6G is referred to as the position, qualification would be the expected context.
Separate acceptance criteria outside the code for qualification would need to be referenced or whatever the manufacturer/contractor required.
It is old but the information remains important for sure.
Have a great day!
You are correct, but it would depend on the fluid service. Cat D is very liberal and allows a lot.
The only way root penetration can be considered excessive is if it can be measured. A maximum 1/16 inch an in no way be determined by radiography.
There are some requirements for "minimal penetration" I know what it is when I see it, but cannot determine it any other way than to measure it.
A SMAW 6010 root with fill and cap with SMAW 7018 will have root penetration. There is not way around it. Heat and gravity does its thing.
If they are concerned with excessive penetration of the bead with sch 40 3 inch the welds should be GTAW.
But when testing you should have clear parameters on what is required. Again, if it cannot be measured, it should not be rejected.
That's the thing Kahunna, from my understanding these folks dont want your standard 1/16 or so interior penetration, they want a goodyear on the inside. The guy I was helping was putting in a decent bead but was worried because it did not hang on the interior of the pipe 1/4 inch.
Sorry, I was thinking the wrong way.
I have to say I have never seen anyone want excessive bead penetration. It results in higher welding cost and in corrosive/erosive environments can cause corrosion/erosion.
As for excessive reinforcement, which this would be, there are limits, but again it is what can be physically measured. And I have never measured the reinforcement on the bead. Even on flanges. The reinforcement measurement is made on the cap only.
Thanks Kahunna. I'm not involved in this in anyway other than helping a guy out. Seems this place is testing for single hand positions so no place in their scheme for me. Still I'm curious to se the actual wps to see what they are wanting. We got to laughing and figured a guy was gonna come in there that has been welding process pipe for years and they will fail him cause he don't have a goodyear hanging on the inside! Good thing is you folks on here have taught me a lot from just reading posts. Thanks again!
If they are working to B31.3, that code has specifications for internal protrusion
Engineering Standards Manual ISD 341-2 Chapter 13, Welding & Joining
Section WFP 2-01 – Welding Fabrication Procedure Rev. 1, 10/27/06
Attachment 2, ASME B31.3, “Process Piping” Acceptance Criteria
1.0 ACCEPTANCE CRITERIA FOR COMPLETED WELDS
1.1 Butt Welds
1.1.1 As-welded surfaces are permitted; however, the surface of welds shall be sufficiently free from coarse ripples, grooves, overlaps, abrupt ridges, undercut, and valleys.
1.1.2 The surface condition of the finished welds shall be suitable for the proper interpretation of radiographic and other nondestructive examinations when nondestructive examinations are required. In those cases where there is a question regarding the surface condition on the interpretation of a radiographic film, the film shall be compared to the actual weld surface for interpretation and determination of acceptability.
1.1.3 Undercuts shall not exceed 1/32 in. and shall not encroach on the minimum required section thickness.
1.1.4 For single-welded joints (i.e., butt joints welded from one side), concavity of the root surface shall not reduce the total thickness of the joint, including reinforcement, to less than the nominal thickness of the thinner component being joined. (This applies only when inside surface of the weld is readily accessible or the weld has been radiographed.)
1.1.5 For single welded joints, the excess root penetration shall be limited to the lesser of 1/8 in. or 25 % of the nominal wall thickness of the thinner component being joined, down to ¼ in. wall thickness. For any nominal wall thickness less than ¼ in., the excess penetration shall be limited to 1/16 in. (applies only when inside surface of the weld is readily accessible or the weld has been radiographed).
1.1.6 Weld reinforcement greater than the amounts specified in the weld reinforcement table at the end of this attachment shall be considered unacceptable.
1.2.1 As-welded surfaces are permitted; however, the surface of welds shall be sufficiently free from coarse ripples, grooves, overlaps, abrupt ridges, undercut, and valleys.
1.2.2 The surface condition of the finished welds shall be suitable for the proper interpretation of nondestructive examinations.
Attachment 2, ASME B31.3, “Process Piping” Acceptance Criteria
Page 2 of 4
WELD REINFORCEMENT TABLE
Thickness of Reinforcement
or Internal Weld Protrusion
¼ in. and under
Over ¼ in. to ½ in.
Over ½ in. to 1 in.
Over 1 in.
Note: External weld reinforcement and internal weld protrusion shall be fused with and shall merge smoothly into the component surface.
Good reading, thanks Robert!
I just wanna ask to have a clarification regarding on how to weld a MS pipe with a size of 150mm x 150mm Schedule-80 using SMAW process. Particularly in a 2G position. Is it upward from 6-3-12 o'clock then downward from 12-9-6 o'clock? Or it will be demonstrated in a upward direction in all quarters of a pipe?
I am very glad for the answer.
2G is a horizontal groove. What you have described is a 5G.
If this joint is welded as part of a qualification effort, it is either welded using uphill progression, i.e. 6 to 12, on both halves. If this is a production weld, progression is limited to what is permitted by the qualified WPS and the welder's qualifications (what he did when he tested).
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