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Why Do Welding Rods Need to Be Heated?

Why welding rods need to be heated before welding

Do you get frustrated when you see your weld come out like Swiss cheese (with porous texture)? And you were wondering what the problem is?

Well, the answer is quite simple—you forgot to heat the rod before welding. 

Wait, why do welding rods need to be heated if the welding process creates heat anyway? 

That’s a great question! Here’s briefly why.

Welding rods may contain moisture. When electricity from welding interacts with water, it generates some unusual results. As you know, heating can drive out this unwanted moisture. But existing moisture content present in welding rods can introduce defects into the weld such as porosity, gas inclusion, and toe cracks. 

In fact, we know that the extremely high temperature used in welding is enough to turn water into steam. Hence, this steam can create hot air bubbles inside the weld. Of course, these hot air pockets will then lead to weaknesses in the joint or weld. The joint won’t look uniform or consistent which then leads to major failures.

The easiest solution for all these problems would be to preheat the welding electrodes before using them. But how do we do it exactly? And what else do we have to know? I will explain everything in this in-depth guide. 

Let’s dive right in.

Do Welding Rods Have A Shelf Life?

The answer is yes, absolutely. Also, it depends on what is the type of rod that you use and the storage condition. In fact, the storage condition for the rod could make a huge difference in its shelf life. 

So, exactly how long do welding rods last? ESAB has given the below shelf life of their rods if maintained at a temperature of 50-90°F and 50% relative humidity.

ESRB Shelf life Chart
ESRB Shelf life Chart

*Shelf life is for the rods that are still in unopened package from the manufacturer

For rods like 6010, as long as you store it in a dry place and not let moisture in, the rods will last for years. As a result, I could use the 6010 rods in my garage for years without any issues. However, it is not the same for all welding electrodes.

Let’s look at the most common rod used by structural welders—7018 (AKA Low hydrogen rod). This means the coating on the rod contains very low hydrogen, which helps avoid cracks in weld (usually called Hydrogen Cracking) and creates less spatter smoother weld, and a quite stable arc. 

Sounds too good to be true? It kind of is… The catch is that this rod easily absorbs moisture that completely turns this rod useless. Hence, the storage condition for 7018 plays a major role in its shelf life. So, how do we store them, do we need any special storage or equipment? 

7018 Welding Electrode Storage Procedure

As I mentioned earlier, the storage condition of the welding electrode (especially for 7018) plays a major role in its shelf life. This is why these low hydrogen rods come in a sealed (hermetically sealed) container. The container seals the rod from external moisture.

Once you open the container, the rod must be kept dry and stored at a higher temperature to prevent moisture or hydrogen absorption from the air. You can store the opened containers in a cabinet or a rod oven maintained at 250 to 300°F. 

Another key point to remember—ideally you don’t want to leave the rods out for more than 4 hours or so. When kept out longer, the rod absorbs enough moisture to lose its low hydrogen property and all its advantages. Therefore, you can take only enough rods for the work that you think you will end up using in the next 4 hours and leave the remaining in the rod oven or cabinet.

This begs the question- what do you do with the ones you accidentally kept out for too long? Well, some experts in the industry would say that and it is a good practice especially in the heavy fabrication industry. Standard says otherwise, as not all companies are ready to throw away the rods as they are not cheap. 

Indeed, there is a solution for re-drying the rods, that will remove all moisture and bring back its properties before welding. So, how exactly do we go about this?

(NOTE: Welding rods or electrodes with designation EXXX8 are all low hydrogen electrodes. The number ‘8’ at the end stands for low hydrogen coating) 

Redrying 7018 Welding rods

Let’s jump straight into the most pressing questions. How do you dry 7018 welding rods? What temperatures should you use?

For a 7018 rod, the standard (AWS A 5.1) suggests a re-drying temperature of 500 – 800°F for 1 hour or to follow manufacturer instructions. Leading welding rod manufacturing companies suggest the following temperatures. You’ll see these in the welding rod temperature chart below.

Lincoln Electric Low Hydrogen Electrode preheating temperature chart
Lincoln Electric Low Hydrogen Electrode Re-drying temperature chart
ESAB Low Hydrogen Electrode re-drying temperature chart
ESAB Low Hydrogen Electrode Re-drying temperature chart

Thanks to technical innovation, the 7018 rods available in the market are far more moisture resistant. Following welding rod numbers will denote them— E7018R or E2018HXR (H4R, H2R, H8R), etc. What this means is that they are tested for their resistance to moisture absorption (the letter ‘R’). 

How long can 7018 be out of the oven? This depends on their make. Some we can leave in the open air for almost 9 hours, compared to 4 hours in standard 7018 rods. 

7018 Welding Rod Re-Drying Procedure

Steps in redrying welding rods:

  • Rods must be removed from the can and placed in a suitable rod oven. The rods should not be cluttered but spread out in the oven. 
  • After that, the rods should be placed in the oven before the oven reaches half the re-drying temperature and shall be held at that temperature for 30 mins. 
  • Next step: The oven shall then be raised to the re-drying temperature and held at that temperature for 1 hour. 
  • Discard the rods if the coating becomes fragile, flaky, or break off while welding. The rod will no longer give you the desired result as expected. 

Don’ts in redrying of welding rods:

  • Re-drying the rods at temperatures higher than the manufacturer’s suggestions or per standard if not specified. 
  • Re-drying more than 3 times for a rod. 
  • Drying for several hours at a lower temperature is not equivalent to drying at specific or standard requirements. 
  • Mixing low hydrogen rods with nonlow hydrogen rods while re-drying as they have different temperature ranges for re-drying and different properties for absorbing moisture. 

This prompts another question—what about other welding rods? What welding rods need to be kept in an oven? Also, do we need to heat them before welding? Do I need a rod oven for those?

Can You Dry Welding Rods In The Oven?

The below table provides some insight into different welding rods and their storage condition and re-conditioning methods. 

Welding rods and storage condition
Welding rods and storage condition

If you are someone who uses mostly 6010, 6011 rods, or any in the category, then you don’t need any special ovens or facilities. All you would need is a cabinet where you can keep your rods safe and away from moisture. 

However, as we know, nothing compares to 7018 rods in terms of smoothness of weld and ease of weld control. So, if you are an avid lover of 7018 rods, then I would suggest you get a small rod oven depending on your usage. While that may seem like a big investment, it will pay off in the long term with quality welds.

I would strongly suggest getting a rod oven, be safe, and keep your surroundings safe. Welding rod ovens are getting cheaper and you can buy a small one that can hold up to 10lbs and doesn’t take up much space in your garage. 

The Bottom Line

I hope this post helped you in understanding the importance of preheating welding rods before welding. As I discussed, storage conditions and type of welding rod would determine if you need a rod oven or not. For 7018 rods, it would be wise to invest in a small rod oven. Any potential moisture can damage the internal metal structure and introduce cracks or other imperfections.

Now that you know why exactly welding rods are heated before welding, you might want to learn how to properly prepare equipment for stick welding. I wrote an article about how to hook up welding leads in here. You might want to check that out 🙂

Frequently Asked Questions

1. What is the purpose of a welding rod oven?

Some welding rods are highly sensitive to moisture. They can introduce hot air pockets into the weld, which will compromise its structural integrity. In general, they use heat to ‘bake’ welding electrodes and drive away water. Ensure you do proper research before selecting a welding rod oven.

2. Do welding rods go bad?

Welding rods are probably the last thing you’d expect to have a shelf life. But, they do go bad, and this is why storage conditions are crucial. Stainless or carbon steel rods have a shelf life of one year. Low hydrogen ones can last around 5 years. Refer to this chart from ESAB.

3. What are low hydrogen electrodes/ rods?

Low hydrogen electrodes work perfectly for high quality, smooth welds. Simply put, it is a SMAW electrode that has less than 0.6% moisture in its coating. Because welding temperatures are so high, any moisture will split into hydrogen and oxygen. 

As hydrogen atoms are tiny, they can sneak between the weld metal structure. When the metal cools down, these atoms form hydrogen gas. And we know what happens when gases from inside the weld—cracks. So, low hydrogen electrodes minimize the risk of hydrogen trapping inside the weld metal.

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