Root opening and groove angle in a CJP weld 1

[SuG89]

Hello,

In the attached image, a CJP weld section is shown. The groove angle is 71.3 degrees. This doesn't fit to any of the prequalified CJP welds shown in Table 8-2 of AISC 13. Would it be ok to use the 60 degree groove angle case from Table 8-2 to verify this weld?

Regards,
Su

 

[Ron]

71.3 degrees is a bit ridiculous. Change the angle to a prequalified groove angle and be done with it.

 

[SuG89]

Thanks for your response Ron. Changed it to 45 degrees.
Regards,
Su

 

[tmschrader]

Hello
We use 45 degrees quite a bit on welds that may not need the full strength of the material thickness. Most everyone in the shop has a 45 deg router. The effective throat distance is a bit less. The 60 degree angle gives a bit more effective throat thickness, if needed. But seldom use it, unless needed.

We welds plates for cranes using a corner to corner weld similiar to as shown but with no groove angle and no weld prep. So it is a really fillet weld. Someone could say that a fillet weld has a groove angle of 90 degrees. But I understand that would not be a exact use of the terminology. I assume there is some reason for a specific profile on the corner in you image.

 

[gtaw]

Using a groove angle of 45 degrees is not a good choice is one is expecting the weld to penetrate the full cross section of the joint. Generally, if the groove angle is less than 60 degrees, the weld size will be on the order of 1/8 inch less than the depth of groove.

The standard groove angle for an open root butt joint in pipe is 75 degrees (ASME/ANSI B16.25). That being the case, 71 degrees isn't far off if CJP is the objective.

As shown in the sketch, the weld size will be less than 8 mm (dimension of the thinner member) due to the configuration of the joint. The being the case, it is unlikely one can take full credit for a CJP.

The joint is not a prequalified CJP per AWS D1.1 or AISC unless it employs backing with a suitable backing bar or unless it is back gouged and back welded from the second side.

I would also point out that the joint as shown will be a bear to align, tack, and weld. Distortion will be an issue unless there is some means of restraining the joint while welding from the open side. A back gouge and back weld operation sounds reasonable if 100% joint efficiency is the goal.

Best regards - Al

 

[dik]

thanks gtaw... I've generally used 60deg to minimise the amount of weld material... I can up this to 70.

I don't spec an angle or dimension it... but show it on drawings.

Dik