3 replies to this topic

[AmoorSaleh]

Dear All,

I need your help choosing the joint efficiency of the welds,

Assume

Given:-

·        hemispherical head which assembled to the shell by "type No (2):- single   

         Welded butt joint   with backing strip… see sketch UW-13.1 (i) ".

·        the manufacturer decides to do Spot just for the longitudinal weld!!!

·        the circumferential weld for the assembled head to shell is done without any Radiographic examination!!

·        I have to draw your attention to: the hemispherical head was formed by one piece only(seamless)

The question is:

The joint efficiency for the head thickness according to the Book should be 0.65, 0.85 or 1 ?

Could you please explain to me how to use it?

[ELEMAN]

Hello everybody:

 

AmoorSaleh, I would like to suggest to you to redirect your query to some very special sites specialized in the topics of welding and its regulation codes.

 

These sites are:

 

1. Eng-Tips Forum.

 

Welding, Bonding & Fastener engineering Forum: http://www.eng-tips....der.cfm?pid=725

 

AWS (welding) Code Issues Forum: http://www.eng-tips....der.cfm?pid=178

 

2. American Welding Society Online Forum.

 

Discussions About ASME Codes: http://www.aws.org/c..._show.pl?bid=57

 

Become a member of these forums is as easy or as difficult as being a member of Cheresources Forum.

 

I hope to see soon your query in any of these forums.

[Art Montemayor]

Amoor:

 

You have not attached or submitted sketch UW-13.1 (i).  So we don’t have any idea of what the joint looks like.

 

Please explain the basic information – such as: 

• Is this a cylindrical pressure vessel with hemi-heads?
• Who specified the vessel?  Who filled in the data sheet?  Why don’t you supply the data sheet?
• Are you the design engineer?  Who is the fabricator?

Since I was a welder during my younger years when I worked as a boilermaker, I can add comments:

•  If you are the design engineer or the eventual owner of the fabricated vessel, YOU are the person responsible for specifying and ordering the type of fabrication you desire – especially the type of steel, the vessel dimensions, the radiographic tests, and the joint efficiencies to be used – according to your specified design and fabrication code (which could be ASME section VIII).
•  We don’t know the diameter of the hemi-head, so maybe the fabricator is capable of forming the head out of one sheet of steel.  This sounds odd, but if it is small enough, he/she may be able to hydraulically press it out.
•  All the hemi-heads I’ve had fabricated (and there have been many) have been segmentally cut and welded with 100% joint efficiency (full penetration) and 100% radiographed.  That was specifically cited in my data sheet which was part of the instructions and contract made with the fabrication shop.

We can’t give you recommendations on what joint efficiency to use or what radiograph level to specify.  That is your decision.  You haven’t given us any basic data on the vessel(?) or what the service is.  We know absolutely nothing (thanks to you) about the ultimate vessel or what service it will be put into, where, and how it will be operated.  We can’t do much with what you have given us.

 

[ELEMAN]

Hello everybody: 

 

By the way AmoorSaleh, in the meantime, before you become a member of some forum, you can read the document prepared by Pressure Vessel Engineering Ltd. http://www.pveng.com...ncies_Notes.pdf.