Can we come to a conclution regarding this topic.?
Can any of the other members reply on this topic.
Interpretation 13-11E of ASME B31.3 will give all options to find out the welding requirement including the one as said by Mr. Raghuram.
Please note that even though the Code allows to use RF pads, nowadays some Clients & PMCs clearly mentions the need of weld 'O' lets in the specifications. So, it is unavoidable to use O lets.
Clients & PMCs, they themselves should understand the problem of chance for less welding at the branch connections due to inspectors less design knowledge and clearly specify the weld thickness required at the branch connections in the specifications. This will avoid the weld failure.
From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of Bathula Raghuram (Mumbai - PIPING)
Sent: 14 November, 2008 11:50 AM
To: materials-welding@googlegroups.com
Subject: [MW:1308] RE: 1307] Re: 1305] welding reqd on a weldolet
I am expecting multiple opinions on this issue from the group members but so far none?. please share your experience (no matter whether it is right or wrong after all we are just learning) , since it is long debated and yet not resolved issue. almost on every project I work for I have an issue with weldolet welding/distortion etc..
On many occasions in the past I have come across Weldolets which have not been fully welded out to the weld line. One in particular resulted in a near catastrophic failure. In general I find that contractors do not fully weld out weldolets to the weld line generally with the mis-conception that provided they have the same thickness as the branch wall they will be O.K. However they need to meet Thermal Stress Analysis requirements and not just Pressure reinforcement. I am neither a designer nor stress specialist bur considering Code" SIF's are lower than set-on branch SIF's since they are based upon the assumption that the Weldolet is fully welded out to the weld line. In not fully welding out the Weldolet then the actual SIF's are far greater than the "Code" values. The problem is that in many cases the Pipe Stress Engineer has assumed that the Weldolet is fully welded out whereas in fact the inspector approves cases where this has not occurred. My opinion is that Weldolets should be fully welded out always and if the parent pipe is so thin that distortion is a problem then use some other type of fitting.
there are some client specifications indicate the the extent of weld required for olets for e.g NORSOK standard M-601 states
"The weld bevel of O-lets shall be completely filled up to weld line on the O-lets. Smooth transition between the pipe and the O-lets is required. Notches below the weld line shall be avoided. Prior to welding, sufficient root gap shall be ensured"
The problem is that olets are manufactured in a combination of diameter groupings to avoid inventory, resulting some of them will have the reinforcement at branching in excess of what is required. also it is because we get Sch40 fittings for sch10 run pipe, since bonny forge does n't have sch10 in their inventory, is n't it? and end up with more welding.
simplest solution would be rather than going thro these complex geometry, we can choose a poorer solution such as with RF pad, after all we can calculate the required thk as per code is n't it?
I hope some national/international code will be published soon on the olet geometry.
-----Original Message-----
From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com]On Behalf Of HAREESH K V
Sent: Thursday, November 13, 2008 4:25 PM
To: materials-welding@googlegroups.com
Subject: [MW:1307] Re: 1305] welding reqd on a weldoletcan we calculate the weld required based on asme B 31.3, the minimum reinforcement required for the branch opening. If so can you send one example calculation.
also how much weld should be done on a half coupling.On Thu, Nov 13, 2008 at 1:46 PM, Bathula Raghuram (Mumbai - PIPING) <R.Bathula@ticb.com> wrote:
there is always heated debate on this between me and the vendors. in my opinion what ever is the bevel provided has to be completely filled since it compensates the area of opening (also called as crotch).
also olet manufacturer (since they are the designers) should give these recommendations. you may check the burst test performed on these olets by mfrs, the minimum weld should be the one they welded during burst test.
-----Original Message-----
From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com]On Behalf Of HAREESH K V
Sent: Thursday, November 13, 2008 9:11 AM
To: materials-welding@googlegroups.com
Subject: [MW:1305] welding reqd on a weldolet
I want to know how much welding reqd on a weldolet. My client is insisting me to weld the total slope (up to the middle of weldolet) on the weldolet. How the welding to be calculated?
Generally please suggest how much welding reqd on the OLETS.
If available can anyone send pictures of the same.
Regards
Hareesh
<BR
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