How To determince Full JOint Penetration

By Stephan (***)

Date 03-13-2008 07:38

sonni,

do a quick forum search by using "penetration". There's a plenty of information on this...

Or have a look upon what Al and the others have explained to me at that time

http://www.aws.org/cgi-bin/mwf/topic_show.pl?pid=58156#pid58156

Best,
Stephan

By swnorris (****)

Date 03-13-2008 10:28

I guess you're asking how to determine whether a joint is CJP or whether it's PJP whenever you see a bevel symbol on a drawing. In my experience, I've seen it shown several different ways. Some just say that a bevel symbol designates CJP unless noted otherwise. Some detailers use CJP in the tail and leave the joint geometry to the fabricator. Some detailers use an AWS D1.1 prequalified joint designation in the tail, such as TC-B4a-GF. Some detailers use only the bevel symbol and leave it up to the fabricator to figure out whether the joint is CJP or PJP. When this happens, sometimes I can refer to the design drawings and make a determination, but on occasion, either the detailer or the EOR has to be called. Regardless, it is the designers responsibility to show the desired joint on the design drawings, and it's the detailers responsibility to show the proper joint in the weld symbol. In my experience, neither one has been consistent in doing so.

By jwright650 (*****)

Date 03-13-2008 15:17

I've instructed my welders to judge CJP vs PJP by the groove weld symbol...if the groove weld symbol has no other infomation shown, that is a CJP,.....if the weld size and depth of prep is given to the left of the groove symbol, then it is a PJP.

By eekpod

Date 03-13-2008 18:32

What John posted is absolutly correct. AWS 2.4 Standard Symbols for Welding states;
6.2.2 Complete Joint Penetration- Omitting the depth of bevel and groove weld size dimentions from the welding symbol REQUIRES a groove weld that extends through the thickness of the joint.

So what that means is unless they tell you NOT to weld it all the way thru (full penetration) per AWS it is considered a full pentration weld. This applies for a square groove joints, (which is always called out wrong on the drawing), single bevel, double V groove, single V groove.

In order for a partial pen, it would need to have some dimentions that are less than the thickness of the part being welded. Let's say a 1/2" plate, but it told you you only had to bevel it 1/4" and put a 3/8 weld in it. That would leave an 1/8" that would not be welded, which is a partial penetration weld.
I hope that helps. Chris

By Bob Garner (***)

Date 03-13-2008 21:07

If it's partial penetration, aren't you supposed to give the effective throat dimensions in parenthesis?

Bob Garner

By jwright650 (*****)

Date 03-14-2008 10:40

Yes, Bob you are correct...the "effective" or "calculated" weld size is indicated within the (...)'s and the depth of prep is indicated to the left of that.

By 803056

Date 03-15-2008 13:21

My experience has been that about 85 percent of all the drawings I review have welding symbol errors.

Think about it for a minute or two. If 85 percent of the drawings are wrong because the designer didn't use the proper welding symbols only 85 percent of the welds shown are going to be what the engineer expects them to be.

If the welder making the weld only makes 85 percent of the welds in accordance with the drawings, that means only 72 percent of the welds are correct.

If the welding inspector only interprets 85 percent of the welding symbols correctly, that reduces the number of properly made welds to 61 percent.

In other words there is the real potential that only 61 percent of the welds deposited are exactly what the engineer had in mind when he sat in front of the computer terminal.

No wonder we depend so heavily on high safety factors and make the welds larger than they need to be. We have to assume that 39 percent of our welds are different than what the engineer had in mind.

I think I will use my birch bark canoe to cross the river this afternoon!

Best regards - Al

By Stephan (***)

Date 03-15-2008 14:50

Heaven forbid, but that's great Al!

Best to you,
Stephan

P.S. Using the birch bark canoe might be the right decision to cross the river... :-):-):-)

By 803056

Date 03-16-2008 03:35 Edited 03-16-2008 03:37

It reminds me of the cartoon where someone dreams of building a swing hanging from a tree branch. What is actually constructed is far from what was envisioned by the originator.

If I could only find a paddle.

I loaned mine one to Joe Kane! Once again, he was up sxxt's creek without one.;)

How's life treating you Stephan?

I'm packing my bags to head back to Georgia in the morning. Have bags, will travel!

Best regards - Al

By Stephan (***)

Date 03-16-2008 11:10 Edited 03-16-2008 13:00

Hi Al,

good to hear from you!

Joe Kane is the man, anyhow!! :-)

Cheers for asking my friend.

I suppose life's treating me as it treats all of us.

Lots of work to be done and much too less time for this extraordinary good forum.

However, I have spent some night time for thinking about darren's post with the "centerline" of a spray arc welded fillet joint.

And... he did it once again by having contorted my tiny brain with his excellent query.

I hope to be able to state my humble ideas on that on the forum very soon. Hope darren wants still even to know what I'm thinking on that!

So have a good time and I'm looking forward to hear from you!

Best regards,
Stephan

By Tommyjoking (****)

Date 03-17-2008 06:28 Edited 03-17-2008 06:31

Al as a side comment most of all our engineers come down to the shop and ask us what weld symbol needs to be on the drawing as well as what welding method would be most effective.....I do not mind this ...I encourage this kind of collaboration...but at the same time it is worrisome if you know what I mean. We still have drawings with the wrong weld designations on them. I find it utterly scary that engineers in the mech class have no knowledge of valid weld symbols. But we do what we can to help them out....all i can say is duck when you hear a jet overhead

Tommy

By sonni Date 03-17-2008 06:39

everybody thx for ur explanation, even a bit blur but i can understand to determine it. sometime in the drawings show only V groove symbol or filet wit weld size, anyway how many % for V still consider full penetration, like sampe, 25 mm plate V groove 10 mm is it still consider full penetration or no?
thx

By Tommyjoking (****)

Date 03-17-2008 08:32

ok as far as ASME and AWS are concerned a full pen weld will exceed the depth of the parent metal to some measurable degree.....so in explanation you may be able to require like on a 1g on .125 plate a total depth of .135 from crown to reinforcement crown....that is not a legitimate spec but just an example of what is commonplace. the weld joint exceeds the depth of the parent metal on BOTH SIDES. That is what you are likely to see on a structural drawing under these bodies standards .....however there are always special cases to which this will not apply at all......READ your standard and READ your drawings........if you have neither of those then do not propose you can come here looking for easy answerers.
Tommy

By jwright650 (*****)

Date 03-17-2008 10:38

Speaking of weld symbols and such...our Lincoln rep dropped by the other day to let us try some of the new Excaliber E7028 and left me with some colorful posters....one with weld symbols shown and the resulting joint and weld shown.

They were awsome, so I had them laminated and I posted them in our shop for reference. I know AWS has nearly the same poster, but these were very colorful and eye catching...I had most of the shop standing around on their breaks reading and looking over these posters.

They left these four posters for me:

>Welding positions for pipe,
>Parts of a weld(colorful, detailed description of a groove and fillet showing the dimensions),
>Typical weld joints, sections and symbols(mentioned above),
>and Welding postions(showing plate configurations both groove and fillet, butts and T's).

If you use Lincoln products, I believe they are free for the asking....

By swnorris (****)