# Carbon Steel Pipe Coupons & Welding



## erikmannie (Mar 1, 2022)

I finally got tooled up for making 8” Schedule 40 pipe coupons. Here is the setup:


----------



## erikmannie (Mar 1, 2022)

I am going to bevel each side at 37 1/2° (75° included angle).

I still haven’t decided whether I will have a 1/16” or 3/32” landing.

For SMAW, I use 3/32” Lincoln Fleetweld 5P+ (which is obviously 6010) for the root. Subsequent passes are 1/8” Lincoln Excalibur (obviously 7018).

I will take pictures of making the 6” long pipe coupons.


----------



## erikmannie (Mar 1, 2022)

The parting went fine once I had my parting tool precisely squared up: 36 RPM, manual feed.

Setting the 37 1/2° angle would have been easier with 2 people.


----------



## erikmannie (Mar 1, 2022)

Now I see that the trick to using a protractor when you’re by yourself is to:

(1) set preliminary angle,
(2) measure the angle that you set,
(3) make an adjustment,
(4) measure angle, and on and on like that.


----------



## aliva (Mar 1, 2022)

Curious, why are you making 8" coupons? Where I used to work all welding pipe coupons were 2", for stick, TIG, whether SS or mild steel.


----------



## mmcmdl (Mar 1, 2022)

erikmannie said:


> (1) set preliminary angle,
> (2) measure the angle that you set,
> (3) make an adjustment,
> (4) measure angle, and on and on like that.


Or just use a sine bar .


----------



## erikmannie (Mar 1, 2022)

The mistake I made with the first pipe coupon is that I should have faced the back end before I machined the end with the bevel and landing.

Here are shots of the tapering, result before lathe file, & result after lathe file plus Scotch-Brite.

Cutting a taper:







Before lathe file/Scotch-Brite:




After lathe file + Scotch-Brite:


----------



## erikmannie (Mar 1, 2022)

And now I notice that all the other pipe coupons that I have made in my whole life were beveled at a 52 1/2° angle (i.e. 105° included angle).







Edit: I took the time to re-taper all of the 8” pipe coupons that I had because I like a 37 1/2° bevel.


----------



## erikmannie (Mar 2, 2022)

aliva said:


> Curious, why are you making 8" coupons? Where I used to work all welding pipe coupons were 2", for stick, TIG, whether SS or mild steel.



Smaller coupons don’t last very long. I like a longer task.


----------



## Winegrower (Mar 2, 2022)

Eric, I don’t even know what a pipe coupon is…do you sell these, or store them up for the winter, or what?


----------



## erikmannie (Mar 2, 2022)

Winegrower said:


> Eric, I don’t even know what a pipe coupon is…do you sell these, or store them up for the winter, or what?


Welding coupons come in 2 varieties: flat & pipe. Welding coupons are used for intensive welding practice. The main benefit is “a *lot* of arc time with minimal prep time”.

The name “coupon” comes from the appearance of a flat, rectangular coupon: it is shaped like a coupon!

Flat coupons can be either fillet or groove. Pipe coupons are always groove. Flat, thick butt joints are always groove.

One characteristic of a groove weld on thick material is multiple passes (multiple stringer beads which make up a multi-pass weld bead).

A fillet weld can be a butt joint, T-joint, edge joint, lap joint or corner joint. A pair of flat welding coupons can quickly be oriented into any of these joints.

With flat welding coupons, you can easily orient them in the (1) flat, (2) horizontal, (3) vertical or (4) overhead welding positions.

Fillet is “F”, and groove is “G”.

So, for example, a fillet groove weld in a flat position is 1F. A groove weld (this would be thick material) in a flat position is 1G. A fillet weld in the overhead position is 4F, and so on.

Pipe welds are usually “5G” or “6G”. 5G is fixed horizontal, and 6G is fixed at a 30° angle. “Fixed” means that you are not allowed to rotate the pipe after it is tacked.

I sell the 8” coupons because I have never seen anything larger than 6” for sale.


----------



## erikmannie (Mar 2, 2022)

At welding schools, most of the time is spent sitting at a bench welding coupons (either flat or pipe). At this point, the student has virtually unlimited access to a supply of coupons, weld wire, stick & tungsten electrodes, etc.

This is why people that go to welding school become such good welders, spending hundreds of hours welding without having to spend time prepping materials.

If there is a secret to how to get good at welding, it is maximizing the amount of time you spend actually welding whilst having access to a *lot* of coupons, weld wire, electrodes, etc.

Somebody who learns to weld by making projects, as functional as that is, will only spend 10-20% of their time welding. These people sure get good at prep & fit-up, though!


----------



## erikmannie (Mar 2, 2022)

Here are some screenshots from the web & YouTube videos that I have saved on my phone. They are so good, I am going to upload them separately.

All of these fillet welds are butt joints:


----------



## erikmannie (Mar 2, 2022)

Most of my welding machines only go up to 210A, so I need to increase these values slightly:


----------



## erikmannie (Mar 2, 2022)




----------



## erikmannie (Mar 2, 2022)




----------



## erikmannie (Mar 2, 2022)

They forgot edge joints. PA, PF, etc. is used outside the USA.


----------



## erikmannie (Mar 2, 2022)




----------



## erikmannie (Mar 2, 2022)

Note the socket welds on the right side.


----------



## erikmannie (Mar 2, 2022)

Again, socket welds (e.g. 2F pipe) on the right side:


----------



## erikmannie (Mar 2, 2022)

I won’t run 7018 downhill:


----------



## Winegrower (Mar 2, 2022)

Eric, wow.   This helps me understand why I am such a crummy welder!   Thanks for the info!


----------



## erikmannie (Mar 2, 2022)

Winegrower said:


> Eric, wow.   This helps me understand why I am such a crummy welder!   Thanks for the info!


Let the fun begin:


----------



## erikmannie (Mar 2, 2022)

I plan to weld all day, & I start my day with this mess. One wonders if I will see an arc today.


----------



## aliva (Mar 2, 2022)

erikmannie said:


> Let the fun begin:
> 
> View attachment 398780


I think you should up your price way too low.


----------



## erikmannie (Mar 2, 2022)

aliva said:


> I think you should up your price way too low.


Thanks, I will strongly consider it.


----------



## erikmannie (Mar 2, 2022)

So my first “1G pipe” effort (I was welding from 9 to 3 o’clock with 3/32” 6010, & 9:45 to 1:30 o’clock with the 1/8” 7018) was rough.

Two of my four 6010 tacks failed as I welded almost 180° around of the root pass. For that 180°, I had a nice 1/16” gap (which was easy money!), but the tacks failing opened up the remaining 180° of gap of 3/16”!

I took the challenge and welded the 3/16” gap which I didn’t have a problem with. It was usually just 2 passes of 6010. I was between 70-80A with the 3/32” 6010 (Lincoln 5P+).

I was very happy with the root penetration, but the root pass was too high. I ground it down to where it should have been with stone, cleaned everything up with a wire wheel, and did a single hot pass of 7018. I was at 120A the whole time with the 1/8” 7018 (Lincoln Excalibur).

At this point, the hot pass was too high! I did not grind that down, and I made two cap passes with 1/8” 7018, & you can see that it turned out pretty awful.

You will see all 360° with these 4 pictures. Very humbling.


----------



## erikmannie (Mar 2, 2022)

Here is a 360° view of the root pass which I am not at all proud of. There is also a 360° view of the back side of it.

This point, I am just uploading welding gore. It looks like I missed a spot on the root pass. Also, I see plenty of places where I did not get full penetration on the back side.


----------



## erikmannie (Mar 2, 2022)

Back side:


----------



## erikmannie (Mar 2, 2022)

This is how I grind it down for the hot pass. It is critical that *no* 7018 punches through the root.


----------



## aliva (Mar 3, 2022)

Not sure what the gap is between the coupons, but it should be no more than the diameter to the root pass rod. Where I used to work all root passes for mild steel was done with 6013 rod. It splatters a lot but easier to control. You may get burn through holes if you go too slow.  Grind any flux off the root and rest is done with 7018, in this case probably 1/8 dia.


----------

