TKY Weld Inspection

By - Date 02-18-2005 15:59

Hey Mike,
Yeah that was a good article. You can find it in the Fall 2004 issue of Inspection Trends.

Drafters always have difficulty with welding symbols for tubular TKYs. It is usually necessary to add a note stating that the welding be in accordance with some sort of procedure that fully details what needs to be done.

As you say, if you have a 22"OD brace member intersecting a 38" chord member at a 45 degree brace intersection angle, the groove angle at the heel of the joint cannot be 45 degrees. Refer to Table 3.6 of D1.1, where for a 45 degree dihedral angle (at the heel of the joint the dihedral angle is equal to the brace intersection angle) you will find that the maximum allowable groove angle is 40 degrees. That is too large (lay it out and see what kind of weld volume you end up with). The minimum allowable is 1/2 the dihedral angle, which in your case will be 22.5 degrees. This should work okay for you.

Be aware that if this is a D1.1 job:
1. The WPS needs to be qualified, and you'll need at least a 6GR test and an acute angle heel test to accomplish that (refer to section 4.12). Your project documents may require additional testing, such as impact, hardness, CTOD, etc.
2. The welder will also need a 6GR and an acute angle heel test (refer to section 4.26, Table 4.9, Figures 4.26 and 4.27).

Find that article if you can. It will tell you how to do the fitup inspection and reference point marking, which will allow the weld to be completed in accordance with the code.

Hope this helps,
Mankenberg

By qcmike

Date 02-18-2005 16:21

Thanks for the quick reply. I will look for the article.

It is a D1.1 job. But the weld joint calls for a 45 degree prep at 3/4" depth for a 3/4" wall pipe. This is a PJP weld. Wouldn't this joint be pre-qualified by referencing 3.12.4 along with figure 3.5 since my joint angle is 45 degrees (greater than the min.=30 deg)?

I believe I have the joint down. Figure 3.5 is helpful. A few months ago I bought a skew-t fillet gauge. It will also be very helpful with the weld inspection.

Let me know if you can offer any more insight.

Mike

By - Date 02-18-2005 18:21

Mike,
If these are indeed PJP joints (3/4" depth of prep on a 3/4" thickness - almost sounds CJP), then you are on the right track. Looks like these joints can be welded with a prequalified WPS in your case, if as you say there will be no groove angles under 30 degrees and you meet all of the other conditions.

Unfortunately, though your skewed fillet gauge is excellent for skewed fillets in plate, it won't do you any good for tubulars. That is because the two surfaces you have to work with are elliptical, not flat, in the direction in which measurements need to be made, i.e. always perpendicular to the weld. The problem is the Tw dimension you'll see in Figure 3.5. In order to verify after welding that the weld size meets the minimum, you'll need reference marks applied at the fitup stage.

Looks like your welders will need either a 6G, a 2G+5G, or a 6GR test, due to the fact that your tubular is less than 24" (see Note 3 to Table 4.9).

Mankenberg