Single V vs Double V
Single V vs Double V
(OP)
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?





RE: Single V vs Double V
RE: Single V vs Double V
Unless its pressurized, I'd figure they call for visual NDE. PT if petroleum and leaks must be prevented - Although he using an API reference, he has not stated his liquid.
Or am I wrong in my assumptions?
RE: Single V vs Double V
RE: Single V vs Double V
RE: Single V vs Double V
RE: Single V vs Double V
even though you bevel from one side, and then make a grove on the other by mechanical means, it's still a double V weld.
it's a lot easier than trying to put in a perfect root pass for x-ray purposes.
RE: Single V vs Double V
RE: Single V vs Double V
RE: Single V vs Double V
Hope this doesn't sound pedantic but if you backgouge it is not a double vee but a single vee, single U combination.
Nobody ever says that because it is always called a single vee with backing, single vee with backgouging or single vee with backgrinding.
If you grind a double vee prep and weld from one side you will still need to gouge / grind the backside anyway.
Regards,
BB
RE: Single V vs Double V
AWS disagrees.
Hg
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RE: Single V vs Double V
if during the course of welding, you get bevels on both sides, mechanical bevel one side and gouging/grinding the other side....it was considered a double v weld.
a single v is when you leave the root in and only weld from one side.
but I've only been doing this for 40 years and things change
in terminology.
RE: Single V vs Double V
AWS A2.4 should clear up any confusion you have.
RE: Single V vs Double V
Hg
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RE: Single V vs Double V
AND I UNDERSTAND SYMBOLS
What i was trying to say is if you make another bevel on the second side of welding, no matter how you get it there,
it's a double v weld.
that's all
RE: Single V vs Double V
V vs. U depends on the shape. Ballbearing1 was saying that if you backgouge, you make the back "V" a shape with a rounded rather than pointed tip, which means it's a U rather than a V and so technically the joint's not a double V. I'm saying (mostly to Ballbearing1, since that's who's making the claim that I quoted) that AWS still considers it a V, as evidenced by the D1.1 figure I cited. I suspect their distinction is a matter of tip radius.
Hg
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RE: Single V vs Double V
RE: Single V vs Double V
RE: Single V vs Double V
RE: Single V vs Double V
you were speaking of the bevel configuration
Guess I should have said....doulble side weld and not a single sided weld
either way....non=essential....to me a bevel is a bevel
ok guys
proceed
RE: Single V vs Double V
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
RE: Single V vs Double V
Your first post made perfect sense to me, maybe you meant something else by it???
RE: Single V vs Double V
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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RE: Single V vs Double V
RE: Single V vs Double V
Obviously I didn't explain it too well.
Regards,
BB
RE: Single V vs Double V
Hg
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RE: Single V vs Double V
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
RE: Single V vs Double V
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.
RE: Single V vs Double V
RE: Single V vs Double V
RE: Single V vs Double V
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
RE: Single V vs Double V
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!
RE: Single V vs Double V
RE: Single V vs Double V
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??
RE: Single V vs Double V
No it does not. Read the attachment I provided a few posts up. It explains it perfectly.
RE: Single V vs Double V
It's your horse now
RE: Single V vs Double V
We still love ya, man! [bigsmile}
RE: Single V vs Double V
RE: Single V vs Double V
neigh, whinny
Hg
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