Bevel Preparation

[Quality2479]

Hi,

What ideal joint preparation would be for a shell horizontal seam joint in Tanks of thickness 15mm and above-

1. Single Bevel Preparation in one shell course (Top) and other shell course without any kind of bevel preparation by keeping edges square.

or

2. Double Bevel Preparation in one shell course (Top) and other shell course without any kind of bevel preparation by keeping edges square.


Is there any standard or any kind of literature mentioning the requirements of bevel preparation or bevel preparation which changes as per the thickness & position of welding.

Thanks

 

[weldtek]

What process are you going to use.

 

[metengr]

I presume you are referring to storage tanks? If so, the code of construction for storage tanks should be used as guidance for welding (including weld joint details).

For example API 650 contains fabrication requirements for oil storage tanks.

 

[jtseng123]

I have to decide many field bevel preparations for pressure vessels (large diameter and length)and piping (also large diameter above 24"), not tank.
This is my personal preference, and has been done many times:
Your option #1 for thick <= 7/8", option # 2 for thk >7/8" if weld from inside is accessible.
This is only for field welding after equipment is stacked up.

 

[steakman911]

I think weldtek has asked the right question.

If its Sub arc, which is likely the most productive process available for the welding of large above ground storage tanks (horizontally), then a single bevel on the upper course would be the preferred joint prep. The SAW process lends itself very well in a series of fillet welds to make the weldment. Speeds of up to 35 ipm can be realized depending on #/size of wires used.

For the verticals I would go with some form of automatic system use a Dbl Bevel with an all position FCAW. For equip, speed of production/quality, my preference would be to use a fully automatic system from ESAB called the Rail-Trac. A completely programmable (EASY to use), lightweight and highly versatile pce of automation.

yes..there is no doubt that capital cost is a consideration: ~60K for a sub arc tank welder and say ~16K for a railtrac. But your welds will be consistent, look great, go in extremely fast and your total cost of welding will be significantly less.

I've used both .. and they work great...just my .02

stk

 

[steakman911]

Correction...for verticals dbl bevel should read single V. Thickness depending... of course.
stk

 

[Quality2479]

Hi,

Thanks for all your valuable answers -

The welding will be performed in Fabrication yard and the welding process which we are going to use is SMAW.In this case which kind of bevel preparation would be ideal to use.

Thanks in advance for your reply.

 

[weldtek]

Quality2479,
For the situation you describe I would opt for the single bevel on the top plate. You'll also need to decide what size land, if any, and root opening, if any, would be appropriate. Whether or not you have access to the back side of the joint will influence those decisions.