×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Maximum size fillet weld that can be done in single pass

Maximum size fillet weld that can be done in single pass

Maximum size fillet weld that can be done in single pass

(OP)
What is the maximum size fillet weld that can be done on site in a single pass?
5 mm? 6 mm? 8 mm?

RE: Maximum size fillet weld that can be done in single pass

According to Structural Steel Design 5e by McCormac & Csernak 2012, about 8 mm for SMAW and 13 mm for SAW process.

A good structural engineer is often a blessing for others.

RE: Maximum size fillet weld that can be done in single pass

The AISC Manual shows the number of passes. See Table 8-12.

RE: Maximum size fillet weld that can be done in single pass

With what size wire or rod?

RE: Maximum size fillet weld that can be done in single pass

(OP)
I am in Canada and don't have a recent AISC Handbook, but you have provided me with sufficient information for me to have a level of comfort that the weld size I want to specify can most certainly be done in one pass. Thanks very much.

RE: Maximum size fillet weld that can be done in single pass

I was told years ago by a mentor 3/16", but I have heard larger recently.

Mike McCann, PE, SE (WA)


RE: Maximum size fillet weld that can be done in single pass

Was not aware of that AISC table. Looks like they added it for the 14th edition.

In any event, AISC lists 5/16" (8 mm) for fillet and single-bevel groove welds.

RE: Maximum size fillet weld that can be done in single pass

It depends on the welding process, the electrode, and the position.

AWS D1.1 Structural Welding Code/Steel provides some excellent guidance if you look at the table 3.7 for prequalified welds.

Best regards - Al

RE: Maximum size fillet weld that can be done in single pass

(OP)

Decades ago I too was told 3/16" was the maximum size for single pass weld, but it seems based on what gatw and others here say it is a little more complicated than that. Since I do not have copies of the referenced documents to which you refer, let me rephrase my question, as follows: For steel plate to steel plate fillet welding on site, some of it involving overhead welding, is there a significant cost difference between 5 mm and 6 mm (3/16 and 1/4:) fillet weld of 50,000 psi yield strength steel. I would say that if the 6 mm weld requires an additional pass, then there is a significant cost and time difference.

RE: Maximum size fillet weld that can be done in single pass

You have not specified the welding process or the electrode diameter.

Best regards - Al

RE: Maximum size fillet weld that can be done in single pass

(OP)
As building structural engineers, we never ever specify the welding process or electrode diameter. We leave that to the contractor's welding engineer. Let me rephrase my question: Are we significantly increasing the time and cost of the project by specifying a 6 mm rather than an 5 mm weld, assuming that the weld length is the same? In other words, 5 mm would work by calculations, but we were considering a 6 mm weld, would we be increasing the welding time and cost by more than 25%?

RE: Maximum size fillet weld that can be done in single pass

No, you pay for a little bit more weld metal and potentially some additional time to put the weld down. Apart from that most of the process is essentially the same. I've seen contractors who price a difference and others who don't for a single pass weld.

More often I find you specify 5mm with a view to some economy, and you end up with an 8mm+ fillet round these parts. Welders like to weld I guess.....

Additional passes are where the cost increases, or full penetration welds, because of the prep required to the plates and preparation between individual passes.

RE: Maximum size fillet weld that can be done in single pass

(OP)
To Agent666 - Perfect. That is clear and concise. Thanks very much. Much appreciated.

RE: Maximum size fillet weld that can be done in single pass

Up sizing from a 5mm to a 6mm fillet leg width should make minimal difference in the weld time - regardless of the position, and the only realized cost increase should be the additional filler metal involved. This would be an increase of weld area of about 44%, and the weld filler metal cost would increase proportionately, though not the total cost of making the weld, which will depend on the welding labor costs in your area.
Dave

Thaidavid

RE: Maximum size fillet weld that can be done in single pass

(OP)
To thaidavid40 (Structural)- yes I see it is a lot more weld material to deposit, I had not thought about it in those terms. I am curious as to why the time to deposit the weld would not increase in about the same ratio?

RE: Maximum size fillet weld that can be done in single pass

They are both a single-pass welds - ergo, the welder moves continuously one time through. The time to deposit the larger amount of filler metal is, electrically speaking, about the same time as needed to deposit the smaller amount. The actual time spent laying down the larger bead is not appreciably longer than the next smaller size bead.

Thaidavid

RE: Maximum size fillet weld that can be done in single pass

(OP)
thaidavid40 (Structural)- ok, that is clear. Thanks very much.

RE: Maximum size fillet weld that can be done in single pass

No one seems to consider the welding process in this discussion. Traditionally, SMAW was used to fabricate structural steel. Large diameter electrodes were able to deposit large single pass fillets with little difficulty. That is no longer the case where fabricators are using small diameter electrode with either GMAW or FCAW. The small diameter electrode makes it difficult to deposit large single pass fillets because the welder must manipulate the electrode to achieve the desired weld size. The manipulation, i.e., weaving, can result in the proper weld size, but it is very likely to suffer incomplete fusion at the joint root.

As a normal practice, I require the welder to pass a T-fillet break test described by AWS D1 structural welding codes. It is surprising how high the failure rate is. I believe the codes fail to take this into account. Many of the code provisions relating to performance qualification were developed when SMAW was the predominant welding process. Using a large diameter electrode, i.e., 3/16 inch, it was easy enough to make a single pass 1/4 or 5/16 inch fillet weld. That is no longer the case. The codes are in agreement that a welder that qualifies on a grooved joint (plate or pipe) is automatically qualified for filet welds. Therein lies the disconnect. My experience has been that a welder that can pass the single pass fillet break test can easily pass the grooved joint test, but a welder that can pass the grooved test will more than likely fail the fillet break test. The disconnect is that the codes (AWS, ASME, etc.) fail to recognize the degree of difficulty the large single pass fillet present when welding with GMAW or FCAW.

Best regards - Al

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources