CJP, Contradiction Of Intent?

Date 06-15-2012 19:45

AWS D1.1 (2010) clause 2.3.5.3 and identical AWS D1.1 (2006) clause 2.2.5.3 state that,
“The welding symbol without dimensions and with “CJP” in the the tail designates a CJP weld as follows: "
(and a leader line is shown and in the tail is “CJP”,see attachment.)
The narrative goes on to say, “The welding symbol without dimension and without CJP in the tail designates
a weld that will develop the adjacent base metal strength in tension and shear.”

I find the statement, "without CJP in the tail designates a weld that will develop the adjacent base metal
strength in tension and shear " to be contradictory to Clause 3.12.1 (2010) as well as Clause 3.12.1 (2006)
which defines a groove weld welded from both sides without backgouging to be a partial penetration weld and
from Table 2.3 (in either edition) we see that PJP welds specifically limit the allowable stresses in tension and
shear to a very low fraction of the filler material strength and in no way relates to "....develop the adjacent
base metal strength in tension and shear".

Unless a shop drawing labels a weld as CJP, or there is some other direction to backgouge, these welds will
in fact NOT be backgouged and will necessarily have to be treated as a lower strength PJP by the designer.

I’m thinking that the first clauses I mentioned (2.3.5.3 and 2.2.5.3) are stated wrongly, but then again why
has no one ever caught this before.

So I would enjoy anyone’s insight on the above.

Attachment: AWSD1.12010Para2.3.5.3.doc (64k)

By welderbrent (*****)

Date 06-15-2012 20:38

Tom,

This has not only been noticed, it has been part of many discussions here on the forum in the past.

But, notice that the first thing you are doing is comparing Table 2.3 and "filler material strength" which is not the same as how the narrative states "will develop the adjacent base metal strength". In many cases your filler material (electrodes= 7018) will have a higher tensile strength than the base metal (not ALWAYS, I said "in many cases). There is to be a recognized distinction between filler materials and base metal.

Second, notice the use of tensile strength as well as yield strength in the various Allowable Stress calculations from Table 2.3. They are not the same and are to be carefully compared when trying to analyze rather the joint has indeed developed the strength of the adjacent base metal.

Thus, when also compared with terminology definitions and weld symbols from A2.4 and A3.0, I don't think it has been "stated wrongly" nor is it a contradiction, necesarily. There may be times where it could be questionable as to how well the base metal strength was actually achieved. But that is the responsibility of the engineer, not the inspector. When the weld is called out for PJP then it does not require backgouging. If it is called out as a CJP then it will be backgouged or have proper root opening with a backing bar of some sort. All in the hands of the engineer and detailers to specify how this is accomplished.

Have a Great Day, Brent

By 99205

Date 06-15-2012 21:22

You know, it seems that more and more I have to say, "that is the responsibility of the engineer, not the inspector".

By tom cooper (**)

Date 06-15-2012 23:20

Thanks for the quick reply Brent.
I searched the forum before I posted, but didn’t find much related to what I’m looking for.

Please let me try to boil down my issue and state it in another way....

We have a large project involving numerous manufacturers and welding contractors. The designers on the project produced many drawings (close to 1000) and on those drawings, welds that “appear” to be CJP** since they are welded from both sides, none of them have applied the “CJP” in the tail note. My claim is that since they have not labeled the welds as CJP, they will NOT be backgouged and by paragraph 3.12.1, they must be treated as a PJP. The engineers are pushing back and point to paragraph 2.3.5.3 by saying they don’t have to be labeled as CJP because the welds “without CJP in the tail designates a weld that will develop the adjacent base material strength…”

** (by welds that “appear” to be CJP, but not labeled as such, I mean for instance a T-joint where the plates being welded 1½ “ thick with ¾” deep bevels on either side).

I don't want to go engineer bashing, but would like to get opinions on this from the experienced folks.

Thanks if you can help.
Tom

By welderbrent (*****)

Date 06-16-2012 00:36 Edited 06-16-2012 12:56

Tom,

The better attachment would be to show us the symbols in question. It is very difficult to get too specific with only verbal discriptions.

But, usually a detail of the joint in question will show either a single bevel so that it would be obvious it required some kind of 'backgouging' to weld the other side or it will show a double bevel which would mean you would get most of your penetration because of the bevel angle. It should also show or call out a root opening or at least a joint detail from Clause 3 which would give the joint details.

But the bottom line is, based upon the questions which have arisen and the disagreement, an RFI needs to be sent to the engineer and as it is their job it will be done their way even if others disagree. Their interpretation will prevail and should be followed. Not much room for argument when they have declared their intention.

Just my two tin pennies worth.

Have a Great Day, Brent

By Shane Feder (****)

Date 06-16-2012 01:57

Tom,
Sorry but I agree with the designers.
You failed to include a significant part of that clause

2.3.5.3 Welding Symbols.
The welding symbol without dimensions
and with "CJP" in the tail designates a CJP weld as
follows:

The welding symbol without dimension and without CJP
in the tail designates a weld that will develop the adjacent
base metal strength in tension and shear

A welding symbol for a PJP groove weld shall show dimensions enclosed
in parentheses below "(El)" and/or above "(E2)" the reference
line to indicate the groove weld sizes on the arrow
and other sides of the weld joint, respectively, as shown below

If there are no dimensions shown for weld size, it cannot be classed as a PJP irrespective of what is stated in Section 3.
Remember,Section 3 is related to Pre-qualified WPSs - Section 2 Design of Welded Connections
Regards,
Shane

By tom cooper (**)

Date 06-18-2012 09:34

Thanks for your ideas Shane-

You're saying that if the designer has not provided E1 and/or E2 information on the drawing or in any way indicated the joint is a PJP, then by default it is a CJP.

I still see this as a conflict with 3.12.1, because if the weld isn't specifically marked as a CJP, there is no other verbiage in D1.1 that directs the fabricator to include the additional work associated with backgouging - the joints will not get backgouged.

Would really appreciate other fabricator input on this.
Thanks.

By Shane Feder (****)

Date 06-18-2012 09:51

Tom,
As I mentioned Section 2 is the relevant section - Design of Welded Connections.
Section 3 is prequalified WPSs.
If you look at 3.4 you will see that all CJP welds have backgouging (other than those with backing bar).
What Clause 3.12.1 is saying is if you have a prequalified weld joint welded from both sides without backgouging it cannot be a CJP, it is a PJP by default.
That has nothing to do with what the designers have designated the joint shall be.

"I still see this as a conflict with 3.12.1, because if the weld isn't specifically marked as a CJP, there is no other verbiage in D1.1 that directs the fabricator to include the additional work associated with backgouging - the joints will not get backgouged."

The weld does not have to be marked as CJP, it is clearly stated in Section 2 that the absense of markings automatically makes it a CJP,
Regards,
Shane

By welderbrent (*****)

Date 06-18-2012 11:04

Looking for a multitude of answers to garner the responses you desire will not change the fact that the issue must be cleared with the engineers on your particular job.

Even if another engineer with adequate knowledge of D1 Codes and supplementary AWS reference documents chimed in and sided with you, you still must satisfy the intent and need of the inspector on your job. When in the shop drawings/detail stage this should have sparked an RFI that would have resolved the matter.

Have a Great Day, Brent

By 803056

Date 06-18-2012 11:04

When the designer provides no weld size or when CJP is not included in the tail of the welding symbol, the default is that the weld must develop the full strength of the adjacent base metal. A fillet weld, double fillet welds, PJP with reinforcing fillet welds, or a CJP can develop the strength of the adjacent members. It is simply a matter of economics and it is the fabricator's responsibility to provide the type of weld and the sizes required to develop the strength required. This approach permits the fabricator the maximum latitude to use the weld detail that is the most economical to prepare and weld. In any event, the fabricator must still pass the drawings back to the Engineer for final approval.

The previous posts have done a good job of pointing out the relevant clauses that pertain to this problem. A quick review:

A reference line with CJP indicates a complete joint penetration weld is required. The fabricator's detailer is required to add the relevant information, i.e., groove angle, root opening, with or without backing. The latter requires back gouging unless the weld detail is qualified by testing. Double sided CJP groove welds require back gouging (a code requirement common to all the codes I've worked with).

A reference line with the required weld size(es) in brackets is a PJP. The detailer has to add the relevant information such as the depth of the preparation and groove angle. Double sided groove welds that are not back gouged are considered to be PJP unless the fabricator qualifies the proposed joint detail.

A reference line without the weld size specified and without CJP or PJP in the tail must develop the strength of the adjoining members again requires the fabricator's detailer to specify the weld(s) required to develop the tensile strength and shear strength of the adjacent members.

Where is the conflict? It is pretty clear if you do not "Cherry Pick" the clauses you chose to read. The user must read the entire code and apply all the relevant clauses of the code. “Cherry Picking” is a rookie mistake. The code must be applied in its entirety, not just a clause from here and there when they suit your position.

Al

By welderbrent (*****)

Date 06-18-2012 11:08

One other point to Al's comments if I might, even after the detailer has done his job at detailing out the joint/design details for all members of the project, it must be submitted to the engineers for final approval. This according to D1.1 and AISC. It always comes back the the project engineer of record. Without his approval it doesn't pass muster.

Have a Great Day, Brent

By 803056

Date 06-18-2012 11:24

Sorry Brent, I though the last sentence in the first paragraph covered me. You are correct in saying the Engineer has the last word on all joint details whether they are qualified by testing per clause 4 or when they are prequalified per clause 3.

How many failures have occurred because the fabricator didn't pass the welding details back to the Engineer or because the Engineer didn't really spend time to review the details proposed?

Best regards - Al

By welderbrent (*****)

Date 06-18-2012 18:02

You don't have to be sorry Al, I do. I totally missed your last sentence in the first paragraph. Just like the in house inspector down here keeps missing totally missing welds even though I keep asking him for his documentation on this new clear weld his welders are using. Must be my eyesight, since I just had another birthday it looks like I need to go see my eye doctor again. :lol:

Probably bears repeating though. But I imagine the main argument centers around the bid price not including the additional time required to do the job that way. So now the arguing starts instead of just clearing it through the engineer and completing the job as required by the EOR.

Tom, I have been on both sides. I have been the welder, forman, fabrication shop owner, and the last few years, TPI. Weld symbols are not ALWAYS as clear as we could wish/hope. That is the function of the RFI and the responsibility of the engineer.

Especially on a larger job, I understand the predicament of not having included enough time to make that kind of change. But it may be required any way and I personally think you are standing on sinking sand. Good luck.

Have a Great Day, Brent

By tom cooper (**)

Date 06-18-2012 11:56

Indeed Al, cherry picking seems to be happening on this project, and I am trying
to connect dots for some who can’t or refuse (I’m talking about my project, not
this forum). And Brent, yes I am answer shopping but, as you will note, to very
specific questions so that I can better understand the full picture myself from
experienced folks as yourselves and deal with the parochial factions that exist – yeah,
believe it or not, on big projects everyone does not play nicely.

I appreciate all of the time you have offered.
Thanks.

By 803056

Date 06-18-2012 11:59

I just reread my post. I really do have to break myself of the habit of using the word "you". It seems too incriminating when that isn't the intent.

Al