General Weld Note Callouts 3

[BPGasparin]

I am working with small machine bases and am trying to figure out what basic weld sizes I should be calling out on the drawing. 4" S40 304-SS pipe machine bases that do not have a lot of stresses acting on them. We have just started to add weld callouts to the drawings and I don't know what basic sizing to call out.

1) What type and size of weld should I call out when a straight tube is being welded to an elbow (the elbow comes pre-beveled)?
2) What size fillet weld should I call out when welding a 1/4" gusset plate to the side of the tube?
3) What size fillet weld should I call out when welding a 3/8" thick foot plate to the 1/4" gusset?
4) What size fillet weld should I call out when welding the 3/8" thick foot plate to the 4" S40 pipe?

I am just learning how to deal with these so any help would be appreciated. Thank you.

 

[Duwe6]

To calculate the Engineered strength* of a fillet weld using 70ksi** series filler metal the formula is:

928 lbs x [size in 1/16's] x [length in inches] thus a 1/4" [4 1/16's] fillet weld welded on both sides, 2.5" long each side is:

928# x 4 x 5 = 18,560#

*Engineered strength means that the appropriate safety factors have been already deducted from the 70ksi material strength.

** 70-series fillers are standard for carbon steel. For welds on 304 using 308L fillermetal, use a constant of 775#.

 

[BPGasparin]

In this case I'm not looking for much in regards to strength. The pipe is more than enough to support what it is. The foot plate is used just to lag it in place and the gussets are more for aesthetics than anything. I'm just looking for the cleanest, proportional, and most aesthetic welds for the sizes I am using. I don't want it to look like too small of a weld, but I also don't want it to be a big sloppy looking weld. What do people usually put on these sizes for a weld?

 

[MintJulep]

People do what ever the hell they want. Then things fail.

Engineers proceed as suggested by Duwe6.

So are you a people, or an engineer?

 

[dhengr]

MintJ:
You have such a way with words and phrases, so succinct. I couldn’t have said it better if I tried. Given his way with welds, one can only imagine how the pipe size or plate sizes and thicknesses were selected or what the loads and stresses are. But, why fret the little stuff?

Actually, I think he needs to go to “Welds is Us,” they have almost every size and kind of weld you could ever want without all that complicated thinkin. Limited color selections, but ya buy them by the pound, so ya can mix-n-match sizes and lengths. They don’t got no ‘too small of a welds’ and they don’t got no ‘big sloppy lookin welds,’ they is all just right. They look ya over, and know just what size ya need. No fuss, no muss. Them weld fittin persons is really good, they’ll check your root and joint, they’ll prep. your joint if you wish, they’ve got some really nice sheer welds too. Then they’ll NDT (No Darn Technology) your entire design for you at no extra charge.

There is nothing more elegant than gussets what ain’t needed, to dress up an overpriced design which has no engineering basis. I’ve always rather liked 12 gussets, they add cost to the job, and they can be arranged to match and align with the signs of the zodiac.

 

[BPGasparin]

MintJulep:
I am an engineer, but I still have to please the people (customer). It's our job to give the customer exactly what they want (we're a custom design/manufacturing company that builds machines specifically for customer's problems, typically to add automation in place of people to remove the "people do whatever the hell they want" problem). If the customer doesn't get exactly what they want, I don't get $$$.

This frame is designed well over what is necessary for the machine to run, but it was designed this way because its being put in a very close quarters work environment that is over-populated with "people" who operate forklifts like they're bumpercars. The frame was beefed up to handle basic forklift bumps. Its not in our best interest of time, resources, or money to calculate every potential environmental hazard (forklifts, etc) that could play a factor into the frame. The gussets came as a specific request from the customer for "aesthetics". Though we didn't agree with it, I still have to add it to the design regardless of whether we agree with what they want or not. Cost is not an issue, because its the customer paying for these expensive unnecessaries.

Because this design is already manufactured well over standards, I was simply looking for basic advise from someone who may have run into similar situations and could recommend what would be a proportional weld. Though this is a menial detail, our company's name is still on the machine and we want to make it as aesthetic as it is functional.

 

[Duwe6]

For "looks right", make the fillet leg lengths the same size as the plate thickness, or one gage-size smaller. By gage, I mean the standard stamped sheetmetal gages from the welding supply. In the smaller sizes [up to 1/2"] they go by 1/16" increments.

 

[gtaw]

If the weld is a double fillet weld, i.e., welded on both sides, the weld leg can measure about 3/4 the thickness of the thinner member and develop the strength of the thinner member if matching filler metal is used.

If a single sided fillet weld is used, the fillet can be about 1.5 times the thickness of the thinner member, but you have to consider the strength of the thinner member. In other words, the weld might be strong enlough to cause a failure through the thinner pipe wall.

If the loads are cyclic, you might want to consider specifying a weld with a concave face, but the leg dimention will have to be increase to account for the concavity.

Good luck.

Best regards - Al

 

[innovation2]

I would just use 1/4" fillets and seal all edges. If they are using a flux core weld process you can generally get a 1/4" fillet in one pass.

Otherwise follow gtaw's advise on weld sizes, good rule of thumb is weld size is minimum of two thickness being welded.

 

[Guest102023]

'... you might want to consider specifying a weld with a concave face, but the leg dimention will have to be increase to account for the concavity.'
_____________________________

That's getting too cute to expect transformation to reality in the shop. In any case, fatigue cracks invariably initiate at the weld toe (assuming acceptable weld quality), and other design factors usually are determinant.

 

[muld0020]

AWS has set minimum weld sizes since this sounds structural. They are also referred to the minimum size that looks good based on plate thickness....I guess my quick ref book (from Lincoln) was written for welders, but it does give a starting point for engineering weld calculations.

Anyway, the sizes are tabulated for full strength carried by the fillet weld and 50% load carried by fillet weld for each varying thickness. For example if 50% strength is required the AWS recommended min fillet size is 3/16" from 3/16" up to 1/2" thk plate.