Weld-O-Lets & ASME VIII Div. 1

[archimedez]

Has anyone ever used a weldolet for a nozzle on a ASME Section 8 Div. 1 Pressure Vessel? Does Sect.8 Div 1 allow the use of weldolets?

I cannot find anywhere in the code where it is clearly allowed or disallowed. Also I am not sure how you would go about adding a re-pad to a weldolet nor even what to use for the neck thickness in the reinforcement calculations.

I have been in this business for a long time and the only times I have seen this was with a different code, not ASME Sect 8. Any thoughts or help would be appreciated.

 

[TBP]

Are there "vess-o-lets" for this type of application?

 

[jte]

Weldolets are typically not used on vessels. One problem is that you will have a hard time determining their area (in every plane) for reinforcement calc's unless you get Bonney Forge (or alternate manufacturer if you are using non- name brand Weldolet equivalents) drawing.

Did I understand you right when you mentioned a repad for an 'olet? Why would you do that?

I have seen half couplings used for small connections. No reinforcing calc's req'd so that makes life a bit simpler. See Interp VIII-1-83-217 for nozzle neck thickness.

jt

 

[Xce]

They are allowed. Most O-lets are self reinforcing connections, and they are used widely on PVs. 2"NPS and under they do not require calcualtions as the drill size opening is to small as per UG-40 something.

 

[archimedez]

Thanks to all - this is not something that I did or would do but it has already been done and I have been ask to verify the design for this vessel.

obviously there are a number of other options that I would have chosen if I had been given the opportunity to do so.

So now my problem is making it work. I have a 5/8" thk. shell and 5/8" thk. heads. so the 2" may not be an issue but the 3" will still be problematic(UG-36). The reason I mentioned a re-pad is that other than cutting the olet off and starting over that is the only option that I can think of for adding additional reinforcement area (I can only add so much weld metal and that does not appear to be enough). I have contacted Bonney Forge and ask for some dimensions. About the only thing that I can come up with is to use the neck thickness of the pipe that corresponding to the schedule of the olet.

I was hoping someone had some experience doing this. I know that it is has been done and may still be done and it may be common practice at some particular shop. All of my experience is in the south with the oil and gas industry and it is not common practice here otherwise I would have seen it by now - and I have not. (Not saying it is not done just that I have not come across it)

 

[vesselfab]

IS THIS A NEW VESSEL WITH A NEW U-1A FORM?

SHOULD HAVE CALCULATIONS TO BACK UP THE DESIGN

THE MANUFACTURER SHOULD FURNISH THESE

 

[archimedez]

This is a new vessel, it is part of a large skid package. A pipe shop with a b31.3 code stamp was going to build it until they realized it had to have a U stamp.

Now another shop with with a U stamp is going to build it. I am doing the calculations for the shop that is going to build and stamp the vessel.

All of the material has already been purchased by the pipe shop. I am just trying to make it work to save as much money as possible by using the material that has been purchased.

I dug out an old catalogue from Bonne Forge from the 60's and found the dimensions I need for the Olets and I have verified that they are acceptabel as nozzle connections. Maybe now I can make it work.

Thanks to all that responded.

 

[CodeRef]

I would like to add my $0.02
I worked w/piping shop where their first attempt at building a vessl utilized 1.5" weldolets on a very thin shell. It was a while back and I cannot remember exactly. However, I will always remember the vessel appearance.

In my opinion, their choice of using a weldolet was overkill and a waste of material for this particular vessel. Especally when they wanted to fill out the reinforcing weld up to the secondary bevel. That amount of weld would have warped the shell excessively because they wanted to improve the vessel appearance.
The proper way to weld out weldolets is explained in detail at

http://www.bonneyforge.com/OletCat.PDF

and go to page 35 (catalog page number, or page 34 of the pdf) which is titled Installation Procedure. This is what has been qualified by testing. Any additional weld doesn't add value.

In my opinion, Some olets may look fine on the right vessel but if you can do with less, go for it. Try to keep it simple, and remember your design and Nameplate/Stamp will be there forever.

 

[vesselfab]

IT'S THIS WAY

the manufacturer should contact his AI to verify it can be used.

I don't know how I would do calculations on a non-exempt opening to prove that it is good

AND

a piece of pipe and a repad is not that expensive compared to cutting off a weld-o-let and rewelding on a pipe and pad.

just because Bonney Forge says it self-reinforcing .....don't make it so. They may 100% reinforce thickness removed on a particular thickness of pipe... but that does not mean it will self reinforce on a vessel that may be twice as thick.

How do you figure removal of corrosion allowance?

So you are a contractor for the vessel shop. You know that their ""assigned"" manager of engineering has to sign off on your calcs and that manufacturer is responsible for your calcs and the other companies drawings.

None of that would fly at my company. Drawings that are done at a pipe shop are usally not complete enough for a vessel to meet code.

And we dang sure know the calcs weren't run.

This is a bad deal all around.

 

[PVinspector]

UG-11 of Section VIII allows a lot of latitude when buying a fitting either to a known ANSI/ASME standard, or to a manufacturers standard allowing use to the temperature and pressure ratings that the manufacturer or standard allows.

The Certificate holder (firm whose name is on the data report!) ultimately must prove the fitting is suitable for the intended service.

It is round, so if you know what it is made from (if you don't, game over anyway) calculate allowable pressure per UG-27 using wall thickness of weld-o-let, and attachment per UW-15 and UW-16.

 

[Salmonslayer]

You may want to be careful here and watch the thicknes of the weld metal. Ensure your procedure is approved for expected weld metal thickness and ensure the welder is qualified for the thickness as well.

 

[vesselfab]

PVINSPECTOR

What thickness of weld o let would you use to do calculations

it constantly changes from bottom....wider in middle...and then thinner at top

 

[PVinspector]

I would use the thinnest dimension if it were me.

 

[archimedez]

Since Weldolets are bought as a pipe schedule; sch. 40, 80, 160 ect. for this situation I used the thickness of the pipe schedule that matches the schedule of the weldolet.

If you look at how a weldolet is made you will see that you have at least that much thickness, probably more, out to the limits of reinforcement. I believe this is a fairly conservative estimate, and everyone that I have ask so far has agreed.

If this had not been enough to satisify the code requirements for reinforcement for the 3" nozzles then I would have had them use either a pipe neck with a repad or a LWN. However the nozzles were adequately reinforced and as Pvinspector pointed out the code is fairly liberal regarding what is allowed so I told them to go ahead and use them.

 

[GenB]

UW-16(2)under 2 in no calcs are needed,
you have a abutting weld and it is permitted,
even on 3in in many cases.- read and read.
calculations for weld strength may be needed tosatisfy your inspector.
bonnie gives you the required weld size already built-in the fitting,
they have analized already the fitting and meet any ASME challenges.
the fittings meet the wall t of a 3k lb cplg
genblr