Lifting a vessel by the top nozzle 2

[Crusader911]

I've been asked to check whether or not we can lift a vessel we are replacing by its top nozzle. Is there any part of the Boiler & Pressure Vessel Code that explicitly deals with this? Anything I should watch out for? Any advice would be appreciated, as this is the first time I've been involved in a lift calculation.

 

[0707]

New vessels should have lifting lugs. If it is an old vessel you are going to replace and that will be considered as scrap iron, then, in that case to lift it by the top nozzle, for safety reasons, you have to see if the top nozzle structure has enough resistance to be lift safely

Good Luck

Luis

 

[prex]

No rules that I know of.
If the design pressure of the vessel times the area of the nozzle is more than the weight of the vessel, you could do that without too much concern, provided your lift point is well centered.
Otherwise you should do a calculation based onto WRC107 or WRC297.

prex

http://www.xcalcs.com

: Online tools for structural design

http://www.megamag.it

: Magnetic brakes for fun rides

http://www.levitans.com

: Air bearing pads

 

[jistre]

Could you possibly have some lifting lugs welded onto the tank instead of trying to lift it by its nozzle? Lifting the tank by the nozzle sounds like something from the makers of Bad Idea Jeans. Even if the calculations say it'll be fine, I've got to think that the nozzle and roof were never designed to carry the load of the whole tank like that.

Lifting lugs would at least distribute the load evenly and can be placed so they do the least damage to the tank in the event of an oops moment.

 

[jistre]

I had an oops moment. I missed the replacement part of your question. I'll have to reverse course and say that if the calculations say the nozzle won't come off the vessel, then lift away. You're not really caring about damaging the vessel you're replacing, are you?

I'm going to go back into my hole and drink some more coffee now.

 

[jte]

Vessels are commonly lifted using a blind flange with a lug on the top nozzle. This type of pick is not unusual on fairly large vessels. One advantage of this type of lifting device for a replace in kind operation is that the same blind/lug can often be used for both the old and replacement vessel.

No part of the Code deals with this. That is not what it exists for.

I would be concerned with a first timer trying to evaluate lifting/rigging a vessel without a mentor. I don't doubt your qualifications - its just that these are not simple calc's, its easy to overlook something apparently trivial, and the consequence of failure can be high.

There is much more than just the top nozzle to evaluate. Having said that, if you are focused in on the nozzle, follow the load path. Start with the pin for the shackle and verify that it is ok with respect to shear. Remember to use allowable stresses for shear, not for tension. Check the lug for tearing at the hole. Check the lug for bending (as the old vessel goes from vertical to horizontal, opposite for new, typically done in 5 degree increments). Check the flange for the same loads as the lug. Check the flange bolting. Check the nozzle neck for tension and bending. Be sure to use compressive allowable streses where appropriate - do not think that you can use tensile allowables here. Check the head for the nozzle loading (tensile, then bending/shear). I've probably left something out…

Then all you have to do is check the vessel shell for structural integrity and check the tailing crane attachment (choker, or more likely, lug or beam(s) on the baseplate).

Good luck, and seek experienced oversight - and not only from an anonymous bunch of folks in a newsgroup…

jt

 

[JoeTank]

Crusader911
Please don't try this unless you have an experienced pressure vessel engineer look this over for you.

Joe Tank

 

[Crusader911]

Thanks for all the advice. I punted the question back to the vessel manufacturer.

 

[LSThill]

Crusader911 (Mechanical)

TECHNICAL NOTE:
REVIEW DENNIS MOSS PRESSURE VESSEL HAND BOOK 3RD
PROCEDURE 7-7
DESIGN OF FLANGE LUGS PAGE 420 - 430

L S THILL

 

[LSThill]

Crusader911 (Mechanical)

Other option is PAULIN RESEARCH GROUP FE-PIPE Lifting Program.

http://www.paulin.com

 

[Crusader911]

Good to know, 1sthill, thanks very much.

 

[JoeTank]

Just another thought regarding the condition of the vessel. If it is being replaced due to deterioration, any analysis of the nozzle/lifting lug needs to consider the current condition, not the as-built condition. can't be too safe.

Joe Tank

 

[LSThill]

Technical Note:

Other Option:
DyanVESSEL V1.0) (w/18 Degree of Freedom)
(Fitness for Service REFERENCE ASME FFS-1)

API 579 is replace by ASME FFS-1
by Paulin Research Group

http://www.paulin.com

L S THILL

 

[zjliang]

Once worked on checking if a pair of nozzles on the transition cone of a tower can be used as "trunnions" for lifting, but it failed from the FEPipe results.

So, totally agree with Joe Tank's comments: Can't be too safe.

 

[gr2vessels]

There is nothing much to add to the jte's experience in the vessel design and erection;- practical experience is obvious. It is quite common to erect the equipment, lifting it by the top nozzle, provided that the nozzle strength calculations support the intended use.
There is a strong trend to deliver to site fully dressed vessels, reactor and columns, including internals, external attachments and top platforms...The column to be erected with the top platform fully installed, must be provided with an erection blind, fitted temporary for the top access opening. This will prevent the complications coming from the interference of the slings with the platform, retrofitting the platform on the column with a secondary/additional crane and additional costs, etc.
Again, this should always be undertaken by an experienced vessel engineer and consulted with the structural engineer.
Cheers,
gr2vessels

 

[rjoaks]

good engineering and construction practice is to lift vessels with lugs designed for that purpose or with slings.
In my 50 + years in the business we never used nozzles as lifting points.
Respectfully rjoaks

 

[jte]

rjoaks-

Just goes to show that different folks have different experiences. You don't state what "the business" is to you; it would seem that I'm in a different "business", with experience mostly in the oil refining world. I've seen way too many good engineering analyses of lifts using top or side nozzles with properly engineered devices (and sucessful lifts) to agree with a generalization that it is not good engineering practice to do so. For many vessels, lugs are a good approach, but trunnions and nozzle lifts are other valid options. Each has its advantages and disadvantages. Slings are well suited to "pots and pans". I don't recall ever seeing a sling being used for a critical lift, though.

jt

 

[AravindSujay]

Ofcourse Nozzles can be used as Lift lugs such that they can withstand the entire vessel weight.

Regards,
Aravind Sujay

 

[Crusader911]

Up until now, I spent my career in the production end of oil and gas. We would not even think of lifting a vessel by a nozzle, so my experience has been similar to that of Rjoaks. I am in refining now, however, and so I'm keeping an open mind about things. I am delighted that I was able to avoid responsibility for this.

 

[vesselguy]

Crusader911,
I just read this post and I felt it serious enough to chime in.

I totally agree with jte's advice to you.

First: Yes, it is not unusual to design a top nozzle as a lift point during erection. In the design of hydrotreaters, FCCU, and other reactor designs this type of lift is common because you DO NOT want any unnesseary external attachments to be welded to the vessel shell due to several factors such as hydrogen service and extreme high temp. Just do a Google search for fabricators such as Belleli, IMV, JSW and you see photos of such arrangements. Keep in mind, these are short (comparatively specaking) and very thick wall vessels, hence the nozzle and the head can withstand the bending stresses from the lift. I would not try this on thin wall (less than 1.5") columns, period. If you know someone working at Fluor, ask them to lend you the Fluor design manual on vessel erection and their Rigging design manual and you'll learn all there is to know about the design. It is the best in the industry, I dare say.

Second: If you never done the calculations for erection loads checks and structural design of lifting lugs then hire someone qualified to do it. It is no laughing matter when a lifting lug or someother parts of the erection equipment failed during a lift (It happens a little more often than we like to know about). The equipments can be destroyed and worst yet people can be killed or injured. I witnessed a near miss incident one time when a freaking exch fell due to lug failure.

As a Professional Engineers, the ethics is we don't do work that we are not qualified to do; we get suppervision or just someone else experienced to do it. I'm sure you are a qualified engineer but haven't done this type of design, so get some help outside a computer forum.

Sorry for long winded post.