D17.1 fillet weld acceptance for concavity

By Lawrence (*****)

Date 04-03-2008 17:36 Edited 04-03-2008 17:38

Alan,

Funny you should ask........

I made some comments on this exact subject yesterday

http://aws.org/cgi-bin/mwf/topic_show.pl?tid=15275

I think the last post in the thread gets to the specifics of your question

By Ringo

Date 04-04-2008 17:41

We do the same thing here.Try .040 tungsten,fuse the root pass,then add wire the next pass.

By OBEWAN

Date 04-04-2008 20:18

I would dig around in D17.1. Offhand, I don't recall specific number limits, just pictures of desired, acceptable, and rejectable profiles. Throat dimensions are more applicable to fillets than concavity dimensions. I could be wrong though, so like I said the spec should be consulted. I don't see how a .005" limit could be maintained without filler wire. We do a lot of autogenous fillets here, and most have a concave radius. It is seldom a problem except for the tiny Hastelloy ones. They are crack prone if in the range of .015" when made without filler wire.

By Lawrence (*****)

Date 04-04-2008 22:39 Edited 04-04-2008 22:42

If you are talking about concave profiles on the front side of a fillet than the text is pretty clear.. The weld size will be measured by the triangle that fits inside the macro section..... If the weld is concave to the extent that the requred weld size is not achieved than it is undersized. If the concave profile when sectioned and measured is adequate (a large enough triangle) than the thing is good.

Now as far as D17 table 6.1 speaks specifically to "concavity" it really does NOT relate much to fillets in my opinion. The proper term in D17 for an overly concave fillet profile would be "Insufficient Throat" or "Insufficient Leg Size"

Look to D17 Table 6.1 Fillet weld size-minimum size when fillet weld size is not stated in the drawing
Here you will find the minumum weld sizes. Again these sizes will be figured from your macro sections. (See Figure 6.1 (C) Unacceptable Fillet weld Profiles INSUFFICENT THROAT)

Here is an interesting note... D17 Figure 6.1 uses a triangle calculated from the root, "theoretical throat" to measure weld size (just look at the picture). While A3.0 2001 Figure 25 (B) calculates weld size in a concave fillet using the Actual/Effective throat. Note D17 Commentary C3.3.3 second paragraph

I think the D17 Table 6.1 reference to "concavity" is speaking to defects illustrated in Figure 6.1 (E) Insufficient Throat

Regardless of Weld Class; The minimum weld size must be 1.5T on a single sided fillet right? Whether the fillet has a concave, flat or convex profile.

If there is some 0.005 concavity requirement on fillet welds, In my opinion it is not found in D17 but might very well be in an individual design specification by the OEM.

PS to OBEWAN: How can an autogenous fillet possibly be acceptable for size per D17 criteria?
I just can't get my brain around this one... You may have to draw me a picture :)

By OBEWAN

Date 04-09-2008 18:16 Edited 04-09-2008 18:19

They are actually lap welds where a tube pilots onto a shoulder or a smaller diameter tube. The corner of the largest OD is burned down to make a "fillet" weld on the "lap joint". I agree too about the largest inscribed triangle point. That is how I have always certified fillets. I suppose a diagram would have to be drawn to inspect some cases if a macro is not available. We usually weld oversize (to the high limit) anyway so it is seldom a problem for us.

By Lawrence (*****)

Date 04-09-2008 18:52

Obewan

That makes perfect sense........ I was picturing a Tee joint in my mind... silly me.