Weld Type 1

[dik]

I'm attaching a 1-1/4 steel plate to a 3/4" steel backing plate. I can use a fillet weld on either side of the 1-1/4" steel plate or use a prepared weld. Does the AISC or AWS have a guide to the minimum fillet weld that should be used based on the plate thickness? and/or is it less costly to use a prepared weld (groove) instead of two large fillet welds?

Dik

 

[phighfill]

AWS D1.1-2004
5.14 Minimum Fillet Weld Sizes
The minimum fillet weld size, except for fillet welds used to reinforce groove welds, shall be as shown in Table 5.8. The minimum fillet weld size shall apply in all cases, unless the design drawings specify welds of a larger size.

Table 5.8
Minimum Fillet Weld Sizes (see 5.14)
Base-Metal Thickness (T)1 Minimum Size of Fillet Weld2
T ≤ 1/4 1/8 (Note 3)
1/4 < T ≤ 1/2 3/16
1/2 < T ≤ 3/4 1/4
3/4 < T 5/16

Notes:
1. For non-low-hydrogen processes without preheat calculated in
conformance with 3.5.2, T equals thickness of the thicker part
joined; single-pass welds shall be used.
For non-low-hydrogen processes using procedures established to
prevent cracking in conformance with 3.5.2 and for low-hydrogen
processes, T equals thickness of the thinner part joined; single-pass
requirement shall not apply.
2. Except that the weld size need not exceed the thickness of the
thinner part joined.
3. Minimum size for cyclically loaded structures shall be 3/16 in. [5 mm].

 

[dik]

Thanks...

Dik

 

[gtaw]

The minimum fillet weld size specified by AWS D1.1 is not based on strength requirements. The minimum size fillet is intended to develop sufficient heat input to mitigate the chance of developing an undesirable microstructure and subsequent delayed cold cracks. The presumption is that all the other requirements and conditions of prequalification have be met with regards to preheat, matching filler metals, listed base metal, etc.

Best regards - Al

 

[dik]

Thanks... 3/8 is adequate, but I was going to use 1/2" on either side of the 1-1/4" plate just because of the potential abuse... this is likely a 3 pass weld and I was curious if a double v-groove weld would be less expensive... the total weld length is only a few feet... just felt a little more secure with the double v-groove... but didn't know if I was inflicting the client with a large cost and whether there are distortion issues that are more likely with one or the other weld.

Dik

 

[phighfill]

Depending upon the application, the double v-groove could be more expensive. If your code requires inspection (X-ray or UT) of the welds and there are problems then the cost would be more. Plus you should think about the time it takes to prep the joint configuration (beveling, cleaning ...).