Weld on leg support 2

[Mohsen_81]

Hello all,

To install a replacement vertical vessel on existing anchor bolts, vendor suggested that legs be split into two parts. The lower part will be delivered to the site sooner to be installed and then later the reactor will be welded to it.
The suggested welding method is as below drawing. Can you advise how can the suitability of this design be checked? Should it be checked with any standard or code, or should it be modeled in any software?

 

[LittleInch]

I would like to see a proper flange so that all the forces and bending etc are known.

Or a sleeve welded onto the top or bottom part which is then welded around the end of the sleeve with vertical load taken by the two ends which will butt up against each other.

The chances of getting these legs to be exactly perpendicular are low and will have a potential for a bent leg look for a long time.

This will for ever look like someone forgot how long the legs were, will act as a water trap and be used for other purposes. If you're there in 5 years time someone will take the p*ss out of you for this...

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[r6155]

@ Mohsen_81
You can make a template of the existing anchor bolt locations and send it to the manufacturer (if possible). Or send a drawing. These options are to avoid legs in two parts.
All calculations will be made by the manufacturer.

Regards

 

[SnTMan]

For the sake of discussion, I am taking the other side:

If the fillet welds attaching the base plate to the lower section are adequate, then using the same filets to join the upper and lower sections are adequate as well. The splice plate is of no particular interest.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[MJCronin]

Ok... Here is my two cents....

Given the fact that this is yet another third-world posting with nearly zero information ..... (What a surprise...!)

What is the service and what are the loadings?..... Is this component 3m tall or a 100m tower ????... Indoors or outdoors ?

Must this vertical vessel sustain Wind and/or seismic loadings ?... Keep us guessing if you can

Are the vertical legs made from pipe or some other type of member (its impossible to tell from your half-assed, incomplete drawing)

What is the the code of record? ..... Do you understand what "Code of Record" means ????

Steel plate is cheap... I would want a plate MUCH MORE THAN 20mm thick to sustain probable misalignment.. Depends on the loadings, of course...

I also feel that full penetration welding of the leg-stubs to the misalignment plate would be a much better choice ....

Let the next round of the guessing game begin !!!!!

MJCronin
Sr. Process Engineer

 

[LittleInch]

MJC,

The OP is from the netherlands I think (NL) and dimensions are provided. It's a vertical vessel ( my guess is a vertical storage tank of some sort)

It is clear the support is made from pipe as it has a diameter (12" pipe).

I'm kind of with you that especially at the mid point of the support it's not a great location, but I think you've gone off the deep end a little.

The OP isn't even an MBA...



Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Mohsen_81]

Thank you all for your replies.
@r6155, that was our first suggestion to the client, but due to some reasons, they decided to proceed like this. Since we are at the latest stages of manufacturing, it is not possible to change it.

@MJCronin, Reactor with mixer installed at the top, total height around 6.5m, TL to TL 3.7m, indoor installation, no wind, no snow & no earthquake.

 

[r6155]

It is a pity that such a short leg has to be made in two parts.
It seems that this manufacturer does not have good experience.

Regards

 

[LittleInch]

If the bottom bit is being made earlier, it's not too late to chop that plate / disc off and fit a sleeve to the bottom section which the top section can then slide into and be fillet welded all round the sleeve. Then it should behave more like a continuous pipe than any other scenario IMHO.

Getting this thing located on all 4? legs is going to be interesting and I think rather difficult to achieve as you would need to support it or locate it securely whilst the welder is busy welding it in place. One big gust and ....

Has anyone seriously thought about how you're going to get it in place without killing someone? Or not making it look like you've bodged it into place and get all sorts of off centre loading going on?

Hence my idea about the sleeves so at least you get it lined up and then slowly lower it in place wher eit is then fixed in position and your can weld it in peace.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[MJCronin]

The way that vessel replacement is done in the USA:

1) Remove the old vessel, retaining the old anchor bolts, Inspect the bolts using UT techniques. Record findings

2) Have the vendor of the new Pressure Vessel visit the site and measure and develop his own anchor bolt template (wood, sheet metal or ?)

See the picture in this forum :

https://forum.nasaspaceflight.com/index.php?topic=49086.3640

3) Receive the new vessel and drop into place

Also, see page 14 of this very useful and fine document, developed by Chip Eskridge:...

https://www.chemicalprocessing.com/...report-avoid-common-mistakes-with-vessels.pdf

I don't like the "Misalignment Plate" idea at all ... I have never seen it done before.

Mohsen_81, has your vessel fabricator ever done this before ? Can he supply you with a list of vessels where this was done ? Can you visit and inspect those process vessels where this installation technique was successfully performed ? ... if not, why not.???

Please respect the members of this forum and continue the thread...

.... and, BTW, LittleInch, the MBA is not a graduate degree ..... it is a disease....

In the final stages of the disease, it makes people give themselves pink stars .....



MJCronin
Sr. Process Engineer

 

[LittleInch]

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.