Single V vs Double V 1

[dursosono]

What the adventage double V than single V for constructed of storeg tank per API 650? I know both of joints are allowed by API 650 and it's not essential variable per ASME-IX. It's horz. & vert. joint of shell to shell. I need suggestion for achieved good result or best practised. Thk shell 8 mm, there are 4 course with diameter 10 m. Welding process is SMAW and will be fabricated on site. How much minimum welder have to used?

 

[Ballbearing1]

Hello guys,
Sorry if my statement regarding U versus V was misconstrued and after reading B3.19 it looks like I was wrong all along (based on D1.1).
When qualifying welding procedures for the Australian coal mining industry to AS/NZS 1554 Pt 1 the predominant application is crack removal.This will be either a single U (plate partially gouged from 1 side) or double U (plate gouged from both sides).
Where I was getting confused is in the pre qualified section a single vee joint welded both sides with backgouging is shown as a symbol with V below the line, U above the line and backgouging in the tail.
Regards,
BB

 

[DVWE]

BB,

Your first post made perfect sense to me, maybe you meant something else by it???

 

[HgTX]

BB seemed to be saying at first that if you start out with a double V prep but backgouge the back side, then it's not really a double V but a V +U combo because the backgouging created a rounded bottom to the prep. But that's not how AWS sees it; they base the symbol on the initial prep.

Vesselfab was saying that if you have a single-V prep all the way through (minus land) and then backgouge, that's still considered a double V, not single V (or V + U, whatever). That's also not the case, per AWS. Check AWS use of backing weld symbol.

Not that any of this has to do with the OP.

Hg

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[DVWE]

BB was initially talking about a Single V groove. After backgouging, it becomes a Single V - Single U combo. Which is correct per the attachment I provided, B3.19. He then went on to say that no one calls it that, which is correct again, as further explained by the attachment. To me, in his last part, he was just reiterating that you will have a similar situation with a Double V.

 

[Ballbearing1]

Thanks DVWE,
Obviously I didn't explain it too well.
Regards,
BB

 

[HgTX]

No one calls it that, including the AWS structural welding codes.

Hg

Eng-Tips policies: faq731-376

 

[Ballbearing1]

HgTX,
I was purely trying to explain my difference of opinion based on vesselfabs statement below.

"If you single bevel the shell plate and weld from one side, and then arc gouge or grind to sound metal on the other side , then you have a double V weld."

If you have a single Vee weld backgouged the detail on the drawing will show a single vee with backgouging in the tail.
This then becomes a single vee / single U combination but nobody calls it that.They will call it a single vee with backgouging but what shape have you created with the backgouge - a U shape.(Unless you are an experienced operator and can create a V shape prep)
Hope that has explained what I was trying to say.
Regards,
BB

 

[hogan666]

Ballbearing1,
I have to agree with HgTX. What you are saying may work as a visual aid. But it is not a correct description of the joint detail. It is non standard. Somewhat like referring to the GMAW process MIG. The majority of people will be able to figure out what it is you are trying to say, but you will also have some that have no idea what you are saying.

 

[DVWE]

You guys are beating a dead horse. BB has already stated that no one calls it that, but his description is correct. hogan666, see the A2.4 that you suggested, and they basically describe it exactly how BB does.

 

[hogan666]

some horses need to be beaten after death, if the point is still not taken.

 

[Ballbearing1]

hogan666,
You are beginning to sound like my ex-wife.
As stated in my original response a single vee backgouged is not a double vee weld but a double sided single vee with backgouging.
I may not have explained it clearly but I think we should agree to disagree, there is not much left of this horse to flog !!
Regards,
BB

 

[DVWE]

hogan666,

Take a look at B3.19 of A2.4 and tell me how that is not exactly what BB said in his initial post.

I am putting away my beating stick now!

 

[hogan666]

hogan has left the building, dragging away the carcass. It's my horse and if I can not beat it in public, I will take my toys and go home.

 

[vesselfab]

ok guys....leave the poor horsie alone


but


if i have a double beveled in advance v joint

weld on side

backgouge the other side

does it become a u groove on the other side??

 

[DVWE]

vesselfab,

No it does not. Read the attachment I provided a few posts up. It explains it perfectly.

 

[hogan666]

DVWE,
It's your horse now

 

[DVWE]

hogan666,

We still love ya, man! [bigsmile}

 

[DVWE]

Sorry

 

[HgTX]

Look at the prequalified joint details in AWS D1.1.

neigh, whinny

Hg

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