HYDRAULIC JACKING FOR FIT UP

[GANESH2005]

For welding shell to skirt assembly of a 30 mm thick, 5000mm Dia CS vessel, we used jacking to close a 50 mm gap for alignment and fit up as per UG 31.

Is this a common practice and is it anyway affect the structural integrity of the vessel.

 

[JStephen]

I don't see that UG-31 relates to the post.

In the tank world, I've not seen hydraulic jacks used for fit-up, but have seen equivalent methods that induce a good bit of force into the parts to be fitted.

 

[codeeng]

No worse than rolling a shell or forming a head.

 

[unclesyd]

codeeng,Beat me to the post.

The metal doesn't know where the force is coming from. We use mechanical and hydraulic jacks to round out SS vessels. 200Ton hydraulic jacks to reshape 60" SS flanges with the AI cheering us on. We expand all types of tubes hydraulically.
A couple of things we have accomplished in forming and reforming some PVs' is I preferred using the remote capability of the hydraulic approach due keeping personnel away from all the stored energy.
Several reasons that you don't see that much hydraulic forming equipment is that it is more expensive and can get messy if not careful.

 

[weldtek]

We too make use of hydraulic jacks to aid fit up. As unclesyd mentioned, be careful of the potential of leaking fuid which would contaminate weld joints, should they be in its path.

 

[GenB]

Depending on the t of the metal, I would perform stress relieve or full PEWHT after welding, just a suggestion
genb

 

[deanc]

Come-alongs,dogs&wedges,jacks,BIG hammers,cranes,tuggers
,fixtures and swearing.

They all work----depends what you are doing and what you start with.

If you have a good fitter you will get what you need with minimum damage.

 

[chicopee]

It sounds as if the skirt sprung back after the forming operation and if that is the case I would reform it a little more to tighten up on the clearance,then use the jack.