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Up Topic Welding Industry / Technical Discussions / D1.6 "Minimum" Fillet Weld Size
- - By FloridaSnook (**) Date 05-07-2003 13:48
D1.1 gives min fillet weld size criteria in Table 5.8. but since I am welding P8 to P8, I am digging into D1.6.

I can't find any reference in D1.6 speaking to a "min" size, only a maximum size in parg. 3.14.1. Does D1.6 address minimum sizes for fillet welds??
Parent - By FloridaSnook (**) Date 05-07-2003 13:51
By the way, we are using GTAW and ER308L.....mainly on square tube steel for platforms and skids.
Parent - - By H.Dibben (*) Date 05-08-2003 16:54
Minimum fillet weld sizes are given in D1.1 to ensure sufficient heat input so that the steel does not cool too rapidly and cause brittleness in the weld metal or HAZ. The chemistry of stainless steel is different, and rapid cooling will not cause embritlement. For the same reason, preheat is not required when welding stainless.

Of course, the weld size must be adequate to handle the forces in the weldment, but this is up to the designer to consider.
Parent - - By FloridaSnook (**) Date 05-08-2003 17:34
I would have thought D1.6 would give minimum requirement so there would be guidance in situations where drawings do not give welding details at all.

In the interim, I have directed my welders to provide a fillet weld size equal to the wall thickness of the thinner of the two members assuming the thicker member is 1/4" or less. This follows Figure 3.2 on page 23 of D1.6 (99) but the figure appears to be intended as a "maximum" and for welds made along edges as in a lap joint.

My welders are now advising me that by having to make the heavier welds, they are experiencing a high degree of warpage and distortation. I simply want to insure we have adequate weld metal at the joint.

Do you think my direction follows good practice and judgement?
Parent - - By H.Dibben (*) Date 05-08-2003 18:32
There is no way to properly give a rule of thumb for weld size.

The weld size should come from the designer of the equipment, as it depends on the force in the weld. To develop the strength of a plate, you need a fillet weld approximately 1.5 times the plate thickness (assuming you are only welding on one side only and the strength of the weld metal matches that of the base metal). So by arbitrarily selecting a weld size equal to the plate thickness, you may not be providing enough weld in some cases, but in other cases, you may be providing a lot more than is required with the consequent problems of increased welding time and distortion.

Parent - By FloridaSnook (**) Date 05-08-2003 18:33
Comment well taken. Thanks!
Up Topic Welding Industry / Technical Discussions / D1.6 "Minimum" Fillet Weld Size

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