Can Attachments be Welded on a Knuckle Region?

You skip over the knuckle region...

That's not the knuckle region.

No, it's not....

https://www.eng-tips.com/viewthread.cfm?qid=421558

https://www.eng-tips.com/viewthread.cfm?qid=425515

Something like this maybe?

That looks like a jacketed vessel for pharmaceutical service, with the legs welded to the outside of the jacket where the ability to sterilise and clean the outside is a major consideration. It is easy to visualise a situation where the jacket is only rated to the maximum pressure of the jacket utilities rather than the inner vessel, which may be well different.

On that basis it may fall outside the Original Poster's quoted standard, and, if so, is discarded on relevance.

yeah it is like this. so normally this is avoided right?

Well if it's a jacketed vessel, then you must know the pressure of the jacket to conform to the proper ASME code...

my situation is also like this the difference is that the there is a toriconical head, but im confused pipe support coming on knuckle?

I'm just not understanding the situation....can you provide a detailed drawing? with the pressure rating? Is this in fact a jacketed vessel? What are your qualifications? Are you a certified fabricator? Do you have a weld sheet?

<...have a ASME div.1, S.S vertical vessel...understanding...cannot weld anything on knuckle of head... ...justify a leg welded on the knuckle region?...>

• By discussion and agreement, and with a witnessed retest after agreement has been reached and the work carried out, by and with the Engineer/Surveyor for the company that is providing burst/collapse indemnity insurance on the vessel.
• Otherwise, make no mechanical alteration to it after final witness test as that insurance provider can walk away from any claim, in the event of an incident, leaving the individual and organisation that caused the deviation from its records both personally and corporately liable in both criminal and civil proceedings in most jurisdictions!

<...is there any reference where it s is written that attachments cannot come on knuckle region?...>

One presumes a copy of the current standard is to hand or, if not, that a credit card and a telephone is available to enable purchase of the same <rhetorical question - NNTR>? One can even do this sort of purchase over the internet these days...

So, one grinds back the 1st weld to attach the leg and then welds over the 1st weld with the 2nd weld leaving some 1st weld inside the leg. It seems to be:

• a lot more work, and
• one is welding in the 2nd weld onto metal that already has a heat-affected zone in it from the 1st weld, and
• a bit stupid, as one cannot inspect the 1st weld inside the leg after the 2nd weld has been carried out to attach the leg, and
• it may cause a rejection at the insurance company's witness test examination as being
• outside the standard, requiring special consideration, for which the fabricator will bear the cost of delays, or
• a way of rendering the vessel as unfit for purpose.

That might be acceptable for some fabrications. A pressure vessel is a special case, which is why it is standardised.

And the reason for wanting to compromise the vessel and to deviate from the standard in this way is what, please, exactly?

Here are a couple of other recommended Vertical Vesselsupport solutions from Hartwell, a UK based Pressure Vessel Manufacturer with decades of design experience.

As shown on the left, you can extend the legs and support the vessel by pads attached to the shell. Easy 100% inspectability...or

Go for the full bulletproof solution.... a complete skirt attached to the TP of the vessel head. Not cheap, but the best solution for tall vessels..... especially in seismic areas

Of course the best choice depends on your particular vessel and the number of nozzles and equipment that must be located below the lower vessel head

Quite.

Make a support to fit it (instead of weld it).

Here is a related discussion regarding nozzle locations in the knuckle region of ASME vessels:

https://www.eng-tips.com/viewthread.cfm?qid=67661