When you weld a fabrication or do a repair job, you might encounter a joint that’s vertical to the ground. Unfortunately, vertical welding is not easy. It needs different techniques and settings than the flat position.
This article will answer all your questions and explain the differences between vertical and flat welding.
To keep things simple, we’ll focus on the most popular arc welding processes, joints (T and butt), and welds (fillet and groove) for mild steel.
Table of Contents
- What is the vertical welding position?
- Why is vertical welding hard?
- What is vertical-up (uphill) welding?
- What is vertical-down (downhill) welding?
- Beads and patterns for vertical welds
- What amperage do you use for vertical welding?
- What is the correct traveling angle for vertical?
- What is the correct traveling speed for vertical?
- Vertical with a stick welder
- Vertical with a MIG welder
- Vertical and flux-cored wires
- Vertical with a TIG welder
- Personal safety
- Tips for vertical welding
- Frequently asked questions
When you weld vertically, the proper term is welding in the vertical position.
What is the vertical welding position?
Vertical welding is one of the four basic welding positions where the joint’s axis is vertical to the ground, at an angle ranging from 45° to 90°. If you have a fillet weld in a tee or lap joint, it’s called a 3F position. If it’s a butt joint with a groove weld, it’s a 3G position. The other basic positions are flat, horizontal, and overhead.
If you want to weld vertically, you can weld up or down, but there are great differences between them. But first, let’s see why vertical welding is hard.
Why is vertical welding hard?
Vertical welding is hard because gravity pulls the molten metal away from the puddle before it solidifies in the joint. Without accurate settings and puddle control, you may encounter defects such as spatter, porosity, undercut, and lack of fusion.
To get satisfactory vertical welds, creating a smaller puddle and keeping it steady from start to end is vital. A smaller puddle is easier to control and faster to solidify.
You create a smaller puddle by using a thinner electrode, lower amperage, and shorter arc length.
What is vertical-up (uphill) welding?
Vertical-up or uphill welding is when you start from the bottom side of the joint and travel upwards. Vertical-up is the proper way to weld thick metals because it offers excellent puddle control and deep penetration.
The main advantages of vertical-up are deep root penetration and good overall fusion because:
- When you weld upwards, gravity pulls the puddle down, so the arc points on the exposed base metal, melting it faster and deeper.
- Uphill needs a slower traveling speed to control the puddle and keep it in place. A slow speed inputs more heat into the metal, offering deeper penetration.
Uphill also offers excellent puddle visibility. This way, you can observe the crater size and how it fills with weld metal.
Another advantage is wider electrode manipulation (weaving). This helps to fill large joints with fewer passes and weld joints with poor fit-up.
Furthermore, the slow welding speed can burn coatings or their residues, for example, galvanization, mill scale, or rust. However, welding over coatings is never recommended for critical welds because they create a weaker joint.
Finally, if your process creates slag (stick and flux-core), gravity will pull it down, preventing the slag inclusions defect.
For metals 1/4″ (6.4 mm) or thicker, uphill is necessary to ensure strong joints. However, you can weld metals down to 1/8″ (3.2 mm):
- If it’s a fillet weld (tee or lap joint) since it can absorb more heat.
- If you use MIG welding because it creates a weaker arc.
Below that thickness, the excessive heat will warp the metals or even burn through them.
The main disadvantage of uphill is that it needs a lot of practice before you start getting good welds. If you try to weld the same way as in the flat position, the puddle will overheat, become too fluid, and drip down. The base metal can also overheat, even turn red-hot as you progress. This can lead to warping or burning through the joint, even if the metals are thick.
A common defect when you weld uphill is unfilled grooves along the bead’s sides (or toes). The arc melted the metal, but the traveling speed was too fast, and the weld metal didn’t fill the crater. We call this undercut.
To prevent these problems, you modify all the welding parameters to create a smaller puddle. You can also use weave beads to support the melted metal as you work.
Uphill welding and arc blow
Uphill tends to concentrate large amounts of heat on the upper section of the joint, because:
- Heat always wants to travel upwards.
- Heat also follows the traveling direction which is also up.
As a result, the two directions drive the heat toward the ending point, making it too hot. The slow traveling speed worsens the effect.
That may result in melting the edges and a defect called arc blow. Arc blow happens when concentrated magnetic forces point the arc away from the joint. As a result, the final bead will be asymmetrical.
To prevent these defects, you can use a run-off tab. This is a small piece of metal (e.g., 2″x2″x the metal thickness you weld), beveled and tack welded at the ending point of the joint.
When you weld and reach the end of the joint, you continue on the run-off tab. This way, the tab will absorb the excessive heat, the ending crater, and delay the arc blow defect. When you finish, you remove the tab.
What is vertical-down (downhill) welding?
Vertical-down or downhill welding is when you start from the top side of the joint and travel downwards. This direction inputs less heat, making it suitable for open root joints and thin metals.
Downhill can weld thin metals because less heat goes into them. This is done in four ways:
- You use a fast traveling speed to control gravity’s influence and keep the puddle in place.
- The arc points more on the puddle and less on the workpiece.
- You weld with stringer beads that deposit less weld metal, thus less heat.
- A portion of the heat travels upwards and away from the traveling direction. As a result, they don’t concentrate in one direction.
As a general rule, for 1/8″ (3.2 mm) or thinner metals, it’s best to weld downhill. Otherwise, the heat will burn through or warp them.
You can weld downhill thicker metals, if you have an open root or if you use a process with a strong arc. For example, stick welding with 6010 or 6011 rods.
However, for most jobs, metals 1/4″ and thicker often have fusion problems with downhill.
Other advantages of downhill are:
- Superficial penetration, low heat input, and low metal dilution are beneficial when you weld hard-to-weld metals vertically. For example, stainless steel or cast iron.
- The fast traveling speed allows thicker electrodes and higher amperage to fill the joint faster.
- The final bead is prettier with a smoother surface.
The main disadvantage of downhill is severe lack of fusion:
- If the puddle overruns the arc, it will act as a barrier. The metals will not melt properly to mix (fuse) with the weld metal. This can affect the entire bead, resulting in a joint that can fail with minimal effort.
- Lack of fusion can also happen if you travel too fast because the arc doesn’t have enough time to melt the metals properly.
- One more factor that causes lack of fusion is the presence of coatings because they act as a barrier.
Another disadvantage of downhill is that you need a symmetrical joint with a precise fit-up. That’s because fast traveling speeds don’t allow wide electrode manipulation to correct a poor fit-up.
Finally, for the same reasons that you get lack of fusion, and if your process creates slag, you will also have slag inclusions in and around the bead.
Now let’s see what bead types and weave patterns you can use.
Beads and patterns for vertical welds
For uphill, you can use straight beads (stringers) or weave beads.
Stringers are considered stronger in many ways, and often are the only permitted way for critical welds done under a welding code.
However, vertical stringers often have irregular and convex surfaces. You also need more passes to fill a thick joint. These make multipass welds hard to do without lack of fusion problems between each bead.
Stringers are preferred for the first pass but weave beads are practical and quite popular for thick joints because they:
- Make the puddle easier to control.
- Momentarily point the arc at the bead’s toes to achieve deeper fusion without undercut.
- Fill the joint with fewer passes.
- Leave a good-looking flat surface.
When weaving, you move the arc side-to-side across the joint and focus it on the cold edges of the previous pass for one second or two. You must pause long enough to:
- Melt the sides, to prevent lack of fusion.
- Fill the craters to avoid undercut.
It’s essential to spend less time when passing through the joint’s center to prevent high buildup. The center is always hot, and enough weld metal will flow to fill it.
Each process favors different weaving patterns for uphill welding, but the most popular is the “Z” weave.
The “Z” weave creates a wide shelf to support the puddle, fills large joints with a few passes, and prevents concave surfaces. The maximum weaving width should be 3/4″ (19 mm). After that, the temperature differences between each side can get too high.
One common mistake with the Z weave is directing the puddle too high when traveling from side to side. Each puddle you make at the toes must connect with the one below it.
Furthermore, to avoid too much heat buildup in the metals, you can pause between each pass to lets them cool down.
When you weld vertical-down, you don’t use weaving. You pass stringer beads with or without a short side-to-side motion to control the speed and make the bead flatter. This way, you can travel fast enough to keep the puddle behind the arc.
Next, we’ll see how the basic settings for uphill and downhill compare between each other and the flat position.
What amperage do you use for vertical welding?
After selecting the correct electrode diameter, vertical-up welding needs a 10-15% lower amperage than the flat position. That’s because it’s a slow process. If you use weave beads, you reduce the amperage even further. On the other hand, vertical-down wants a 10-15% higher amperage because of the necessary fast traveling speeds.
For uphill stringer beads, you set a lower amperage to create a smaller and less fluid puddle that’s easier to control. This allows the puddle to stay in place. Also, the workpiece will not overheat, preventing defects such as arc blow and warping.
With weave patterns, the heat buildup is much higher and the puddle will become too fluid. To avoid this, you want to set the amperage much lower.
If you use a stick welder, further reducing the amperage can surpass the rod’s lower amperage range. The rod will not melt properly and will tend to stick to the metal. For this, you must select a thinner rod size. Then you reduce the amperage by 10-15%.
You probably don’t need to change the wire if you have a MIG welder because wires have a wide amperage range. To set the wire speed and voltage, you check the manufacturer’s chart. But these settings are for the flat position.
For uphill, you select the settings for one thickness under (or two for an open root pass). Then test the settings and adjust them to get a small arc but without causing lack of fusion.
For downhill, you want a higher amperage to melt the filler metal fast enough to compensate for the fast traveling speed. Also, a higher amperage will create a stronger arc that will push back the puddle and keep it in place.
For stick welding, you can select the same or even a thicker rod, depending on the metal thickness. After that, increase the amperage by 10-15%. For a wire feeder, you set the settings of the next metal thickness.
At first, it might seem odd that you set higher amperage for downhill because it welds thinner metals. But the traveling speed has a higher impact on the heat that goes into the base metal than the amperage you set.
What is the correct traveling angle for vertical?
Vertical-up welding needs a small traveling angle of 0-15° (below horizontal) to keep the arc small, control the puddle easier, and melt the base metal deeper. Vertical-down requires a greater angle of 15-20° so that the arc can push back and hold the puddle in place. If your process creates slag, you use an even larger angle (20-30°) to keep it from dripping.
Vertical needs smaller traveling angles than the flat position. You also want to keep the angle steady all the way through to avoid defects.
The working angle is the same as in the flat position, 90° for butt joints, 45° for tee joints, and so on.
What is the correct traveling speed for vertical?
The traveling speed is also different from the flat position.
For vertical-up, the traveling speed must be slow enough to fill the bead’s toes to avoid the undercut defect. On the other hand, for vertical-down, the speed must be fast enough to prevent the molten weld metal from dripping ahead of the arc.
Uphill uses a much slower speed to support the puddle, especially for weaving beads. But if you travel too slow, the puddle will become too fluid.
Downhill always needs a faster speed, but traveling faster than necessary will not give the arc enough time to melt the metal.
As a general rule, you use a traveling speed that points the arc to the first 1/3 of the puddle.
Now, let’s see how capable each process is for vertical welding.
Vertical with a stick welder
With a stick welder, you can weld uphill or downhill if you select the proper welding rod. Rods with 1 as the second from the last digit in their identification (Exx1x) can weld vertically. It’s impossible if it’s 2 (Exx2x).
Exx1x means these rods can weld uphill, but most have problems when welding downhill. For example, the popular heavy-duty 7018 rods cannot weld downhill. The easy-to-use 6013s can weld downhill if you select diameters 1/8″ or thinner.
Only the 6010 and the 6011 rods can weld downhill with excellent results, even with thick diameters.
Stick rods create slag material that helps support the puddle for uphill welding. However, slag is a problem for downhill, and you need a wide rod angle of 30° or larger to keep it back.
The E7018 rod is the best for uphill because it deposits the strongest and most ductile (elastic) weld metal. It also fills large joints faster than the other rods.
The E6010 and the 6011 rods are ideal for welding demanding joints downhill, for example, pipe open root joints. However, most common stick welders cannot burn 6010 rods.
As an alternative, the 6013 rod is ideal for thin sheet metal or joints with poor fit-up.
Holding a tight arc length, no more than one-rod diameter, and keeping it steady all the way through is essential for stick welding. If it’s longer, the arc will become unstable and hotter, creating sparks, spatter, and undercut. In addition, the puddle and slag will become too fluid and drip down.
Weldpundit has a detailed article on how to stick weld vertically, including rod amperage charts, and weave patterns for cellulosic rods.
Vertical with a MIG welder
With a MIG welder, you can weld vertical up or down if you set a metal transfer more that can freeze the puddle fast enough. There are two suitable transfer modes, the popular short-circuit mode, and the costly pulsed mode.
One reason why MIG is limited for vertical welding is that MIG wires don’t generate slag. Slag is helpful to support the puddle when welding uphill.
The short circuit mode (or short-arc) is the most popular. Most single-phase MIG machines work only with this mode.
This mode doesn’t keep the arc on all the time. Instead, the arc stops and reignites many times per second. This creates a small puddle that is not very hot and freezes fast.
But a weak arc means that it’s hard to melt thick metals. When welding uphill, a weak arc can cause incomplete root penetration and lack of fusion at the bead’s toes or between multiple beads. These defects get far worse if the metals are not clean.
For uphill, short-arc needs torch manipulation that points the arc into the joint’s root to avoid fusion issues. The upside-down “V” offers the best root penetration, especially if the metals aren’t clean. It can fill small joints with one pass. For additional passes, you can use the Z weave.
You can also use the triangle weave, which also penetrates deep into the root. This pattern deposits more weld metal than the “V” and creates a better-looking bead.
A short stickout of no more than 3/8″ is also important for deep penetration.
Short-arc can also cause fusion problems when welding downhill. That happens because the fast traveling speed may not provide enough heat to melt the metal.
If you weld metals thicker than 1/4″ and your project has demanding service conditions, it’s best to switch to stick welding with 7018 rods.
The pulsed mode is a modified version of the spray mode. This mode can weld uphill or downhill thin and thick metals. But it’s expensive to use for regular jobs because you need:
- A complicated and high-amperage machine.
- A high argon gas blend, for instance, C10 (10% CO2 and 90% argon).
The other two metal transfer modes, spray and globular, create a puddle that’s too big, hot, and fluid for vertical welding.
You can also read this detailed article on how to MIG weld vertically.
With a MIG welder, you can also use flux-cored wires.
Vertical and flux-cored wires
With the proper flux-cored wire, you can weld vertically both up and down. If the number before the “T” in the wire’s designation is 1 (Ex1T-x), you can weld vertically. But if it’s 0 (Ex0T-x) you cannot.
Flux-cored wires are tubular, filled with flux material that creates slag. Slag can support the puddle when you weld uphill. But it creates slag inclusions when you weld downhill.
The problem with cored wires is that each one has its own behavior. Others weld only uphill, others are better for downhill.
The most popular cored wire is the E71T-11, a shelf-shielded (FCAW-S) wire that creates its own shielding gases without a gas cylinder. Since it has a 1 in the proper place, it can weld vertically up or down.
The E71T-11 can give good beads for downhill if you ensure that the arc stays ahead of the slag. However, welding thick metals uphill needs some practice because the wire generates a fluid slag, making it harder to support the puddle.
For uphill, you point the wire perpendicular to the joint. For porosity problems, you can try a 5-10° travel angle, but pointing down, not up. With this wire, it’s best to use a triangular or a Z weave pattern.
For downhill, use a 30° or larger angle and pull the torch with a slight side-to-side movement.
Cored wires have a lower tolerance for wrong settings than solid MIG wires, so try to set voltage, wire speed, stickout, etc., as accurately as possible.
E71T-11 wires, up to .045″ (1.1 mm) thick, aren’t suitable for metals thicker than 5/16″ (8 mm) because the bead will become brittle. A brittle bead may crack if the joint takes heavy stress.
There are also gas-shielded flux-cored wires (FCAW-G) such as the E71T-1. These wires are great for vertical-up because they:
- Don’t need electrode manipulation, wide triangle or Z beads, only stringers. They are the easiest way to weld uphill.
- Penetrate thick metals without lack of fusion or root penetration problems.
- Deposit more weld metal than all the other processes, increasing productivity.
- Use cheap C100 shielding gas.
However, gas-shielded wires need a high amperage machine and are more expensive per weight. In addition, they are hard to find in thin diameters and small spools.
Vertical with a TIG welder
TIG is a true vertical position process. It can weld both uphill and downhill without going through the trouble of finding a suitable rod, like stick welding. Or use specific metal transfer modes like MIG. Also, there is no slag material to worry about.
TIG has excellent heat control, so you can control the puddle’s fluidity and keep it in place:
- You manipulate the TIG torch with one hand and add filler metal with the other. More filler metal freezes the puddle, and less keeps it hotter.
- You can use a foot pedal to directly control the amperage as you weld.
- Or use pulsed welding that penetrates the metal deep without overheating the puddle.
This way, it’s possible to weld uphill metals thinner than 1/8″ without overheating them or downhill without using fast speeds.
If done right, TIG will not create sparks, spatter, porosity, or undercut, leaving a perfect bead. That’s important for stainless steel or aluminum.
However, TIG has some difficulties. TIG takes a long time to deposit weld metal, making filling thick joints time-consuming.
For uphill, the most practical thing to do is pass a quality root pass with TIG and then stick weld with 7018 rods to fill the joint.
Another disadvantage of TIG is that you need to clean the metals perfectly. Otherwise, the tungsten electrode will be contaminated, forcing you to stop welding and regrind it.
To start practicing, you can weld up or down fillet welds or closed butt joints without using filler metal. But decrease the amperage by 10A.
Vertical welding exposes you to hot spatter much more than the flat position. Spatter can land on your skin at a temperature of, 2700° F (1500° C). It can also damage clothing that isn’t heat-resistant.
To protect yourself, you want to wear some additional protective equipment:
- Ideally, the arc shouldn’t go higher than your chest height. A pair of long leather sleeves can protect your arms.
- If the arc goes higher than that, wear a leather jacket, and cover the top of your head with a welding cap.
Never wear synthetic clothing or shoes when welding. Even light sparks or spatter can penetrate them, melt them, or set them on fire.
Wide-spread spatter also means a greater chance of fire if flammable materials are nearby.
Tips for vertical welding
- Always try to clean the metals. Uphill requires clean metals to offer the strongest welds, and downhill to prevent the lack of fusion defect.
- Vertical is easier when the base metal is at 45° and harder at 90°. So if you want to practice, it’s best to start at 45°.
- Ensure you remove tools and equipment from the area because welding spatter can damage or permanently scar most surfaces.
- Vertical welding needs concentration and stability. Try to prop on a nearby surface to stabilize your body. You can create a temporary one by placing a vise grip close to your work. You can also tack weld a piece of metal for the same purpose. Also, keep your working elbow close to your body to minimize shaking. For uphill, try to position your work so that when you finish the bead, your hand won’t be above your heart level. This way you will have good arc visibility and your hands will be more stable.
- Before you start, run a couple of dry runs to test your position, angle, freehand movement, etc.
- For uphill, it would help to pause a few minutes between each pass, to prevent overheating the joint.
|1/4″ and thicker||Thinner than1/4″|
|Amperage||10-15% lower||10-15% higher|
|Travel angle||0-15°||15-20° (double if slag)|
|Common Problems||Fluid puddle, |
|Lack of fusion, |
|Potential arc blow||Yes||No|
Frequently asked questions
Is it better to weld up or down?
Since welding is about strong joints, for most jobs it’s better to weld uphill rather than downhill. This way, you have higher control over the puddle, penetrate the metals deeper, and have better visibility. Downhill is helpful for thin metals to prevent blowing through or warping them.
Is it easier to weld uphill or downhill?
It’s much easier to weld downhill because it requires less skill to control the puddle. You don’t need precise electrode manipulation or weaving patterns. When you weld uphill, you use complex weaving techniques to create a shelf to support the puddle. This requires a lot of skill to do it perfectly.
When you weld downhill, you don’t build a shelf, gravity pulls the puddle, and you let it happen in a controlled manner. On the other hand, uphill is perhaps the most difficult position for plate metal.
Still, downhill welding is much harder than the flat position. If possible, position your work in the flat position so that gravity helps you fill the joint instead of being a problem.