How to handle o-lets in Sec VIII Div 1

[halgodal]

I am sure this is an easy question, but how do you handle calcs for o-lets per the code? I cannot find any examples of them in UW. Specifically, I have a 3/4"-3000# WOL to put on a 2.75" wall vessel.

Also, if anyone uses Compress, is there a way to do it in the program?
Thanks!

 

[LSThill]

Bonney Forge

http://www.bonneyforge.com

 

[halgodal]

Thanks, but I already looked there for guidance.

Anyway, I don't think my A.I. will buy off on bonneyforge.com.

 

[unclesyd]

I have never seen any problems with a whole bunch of AIs' when a Weld-O-Let is properly welded out. We have gobs and gobs of them in service with no problems with fabrication and inspection other than sometimes we get too much weld metal.

O-Lets are taken as fittings when, again, properly installed.

We use both the butt weld and socket type with only one or two threaded that slipped in. We do some RT along with MT and PT. RT is not considered a complete examination but will give one a general idea of the weld quality.

 

[halgodal]

I agree that they are acceptable by code, as I have seen them used for years. But, I was just trying to find the proof in the book as backup to one of our clients since our ASME software does not have them as valid selections.

 

[PVinspector]

I guess you are finding out that with the Code, there are no easy questions

UG-11(a) will allow for receiving, material ID, etc.

UW-15(b) tells you that no strength calc.s for attachments for pressure loading required for this type of attachment.

To prove out the wall thk. calculate peer UG-27 using stress value of o-let (eg. SA105, or whatever it is) and verify that o-let is as thick as required t min. for the design pressure. If the mfg. rates it as 3000# it should be good for more than that at normal temperature ranges.

 

[CodeRef]

Your question should be directed to Compress (Codeware) if these fittings cannot be selected as valid. Isn't there a "custom" feature to Compress nozzle calculations?

As far as the Code is concerned, UW-16(f) is as close as you will get when it comes to standard fittings.

Do as PV Inspector recommends, it is easily done. I have even developed an excel spreadsheet for weldolets where you input the dimensions to determine acceptance. Now, if I can put together a spreadsheet, I am sure Compress has some similar feature.

 

[unclesyd]

6. Specify Piping Code (if available):

Examples: ASME B31.1, B31.3, B31.4, B31.8, ASME See VIII & ASME Sec I Branch Connection fittings are engineered fittings. Stock fittings are designed using "proof of design" Burst Tests. ASME B31.1 and ASME B31.3 codes accept Burst Test Design fittings. ASME Section III also accepts Burst Test Design fittings.

ASME Sec VIII, Sec I, B31.4 and B31.8 require additional design considerations and Burst Test design stock fittings may not meet specific code requirements in certain applications. They, as well as some specifications, require area replacement calculations as proof of adequacy. The requirements are project specific and WFI must be consulted and provided with the following additional ordering information:

Design Code & Edition/Addenda
Design Temperature
Design Pressure
Corrosion Allowance (if applicable)
Design/Location Factor (if applicable)

Adding to the above here are two design conditions that may call for calculations, clustering and cyclic service.

As Bonney Forge has bought out WFI I would imagine that this still holds true. MSS SP 97 has a method to calculate Olets, so I've been told.

This was taken from the WFI catalogue pdf concerning Olets.
I personally have never seen where it was deemed necessary to do an area replacement calculation when Olets were used on a Sect VIII design. This maybe due to size ration always being high. I can only recall 4" on large diameter Olets on vessels.

 

[GenB]

Hi, I use CEI/APV10
Fittings are acceptable just choose the proper welding
design. usually even a std 3000# SA105/B16 fitting
can meet acceptable thickness depending on the pressure
and temp. thread/weld'olets excede the above since they are self reinforcing.
genb