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Enhancing Welding Efficiency with Rod Ovens – How They Work

Date: 04-07-2024
Stick Welding

Rod Ovens – How They Work - Alphaweld

Welding and moisture typically don’t go well together. Welding rod ovens ensure low hydrogen content in the stick rod flux content. Many welding jobs don’t require using a rod oven. However, critical welds that must be welded according to code often require using a welding oven.

What is a Rod Oven?

Rod ovens are designed for stick rod storage and baking. Also referred to as electrode holding ovens or electrode stabilisation ovens, these ovens heat the SMAW electrodes to the specified temperature. Ovens bake out hydrogen, which significantly helps in preventing hydrogen weld cracking.

How Rod Ovens Work

Rod ovens can bake the rod or be used to keep the electrodes at specific temperatures. The difference is primarily in the operating temperature range, with baking ovens working at higher temperatures.

Ovens heat the rods using the simple principle of resistance heating. The current flows into the heater, which resists the flow and heats up. Next, the heat is transferred to the electrodes via radiation. This is typically how a kitchen oven works, only rod ovens are specifically designed for far higher efficiency, safety, and accuracy of applied temperature.

There are two primary types of rod ovens:

  • Stationary, in-shop rod ovens - These have a high capacity, like the Smithweld Baking & Storage Oven, with a 130kg capacity and a 50-400°C temperature range. 

  • Portable rod ovens - These are much lighter and smaller in size, and allow you to store a large number of electrodes when working on-site. For example, the Weldclass portable electrode oven has a capacity of up to 10kg and a 50-200°C temperature range.

Electrode ovens use a thermostat for temperature regulation. The probe extends into the oven and detects temperature before sending it back to the thermostat. Once the set temperature is met, the thermostat shuts off the heater.

Most importantly, rod ovens use high-end insulation materials to ensure an even temperature gradient and prevent excessive heat loss. That’s one of the reasons why you should use ovens specifically designed for rods over any DIY solution.

What Applications Require a Rod Oven?

Typically, most critical applications like shipbuilding, pipelines, petrochemicals, ASME pressure vessels, and structural steel will require using a rod oven for stick welding jobs.

Stick electrodes are covered in flux, and this flux can pick up moisture from the air. So, once the electrode package is opened, rods slowly start accumulating moisture. The air humidity determines how fast the rods can pick up moisture. Most critical welding tasks include a procedure specification that tells the welder how long before the rod must be rebaked, or at what temperature it needs to be held in the oven.

Low-Hydrogen Electrodes

Low hydrogen stick electrodes, like the famous E7018, have a particular susceptibility to moisture. They have a very low hydrogen content, making them ideally suited for critical applications where the risk of hydrogen cracking must be minimised. However, if they pick up hydrogen from the air, they won’t be so “low-hydrogen” anymore.

Once you open the factory package, you should store low-hydrogen rods at 120 to 150°C, but actual storage may vary depending on the application. E7018/E7028 exposed to air for less than a week without direct contact with water should be dried in an oven at 340 to 400°C before use. 

Unless kept at proper temperatures, low hydrogen electrodes can cause weld defects like porosity, rough weld surface, and hydrogen cracking.

Non-Low Hydrogen Electrodes

“Regular” electrodes, like the E6012, E6013, and E7014, aren’t designed for applications where low-hydrogen electrodes must be used. They can be used in such applications, but they pose a higher risk of weld cracking. So, these are two separate electrode types. 

There is less need for using rod ovens for these stick electrodes, but they can still require pre-drying, drying, and storing in the oven, depending on the application.

Excessive moisture in non-low hydrogen electrodes can cause increased spatter, tight slag, undercut, porosity, erratic arc, and similar issues. So, if they pick up moisture from the ambient air, they can sometimes be conditioned in the oven.

What are the Best Portable Electrode Ovens?

For many on-site jobs, these rod ovens will provide you with enough power for adequate electrode storage before use. However actual use cases may vary depending on the code you follow and the electrodes you use.

Need Additional Help? Alphaweld is Here for You

If you need additional guidance choosing a rod oven for your application, contact the experts at Alphaweld – we’re always ready to assist.