Keen KHT-200 SMAW Electrode Rebake Oven

About the KHT-200 Electrode Rebake Oven – 200 lbs. Capacity

The Keen KHT-200 is an electrical, high-temperature industrial oven that is designed for rebaking flux-coated, shielded metal arc welding (SMAW) electrodes. It has a 200 lb. storage capacity and a temperature range of Ambient-999°F (Ambient-537°C).

For welding electrodes that have been contaminated by moisture, the high temperature KHT-200 rebake oven is your answer. Highly efficient and easy to use, it is the perfect solution to restore up to 200 lbs of moisture-contaminated shielded metal arc welding (SMAW) electrodes.

Heavy-Duty Construction Features

• Durable powder-coated steel exterior
• Welded construction
• Angled perforated shelving induces natural convection
• Heavy-duty reinforced door, door latches and door handle • High-strength door gasket with 304 stainless steel knitted wire core and high-temperature fiberglass overbraid • Pockets at oven base for easy transport by forklift
• 1 year limited manufacturer warranty

Performance Heating and Safety Features

• 4" (2.54 cm) thermal insulating wool for energy-efficiency.
• Long-lasting 1000W UL®-approved Incoloy-sheathed tubular heating element for effective heating.
• Adjustable proportional integral (PI) digital controller
• Stable, reliable loop feedback temperature control
• 3-digit LED temperature indicating display
• Handy tactile increment/decrement keys on the controller’s water-resistant front panel enable easy temperature set point adjustment
• Temperature readout in Fahrenheit or Celsius
• Adjustable, thermocouple-actuated manual reset over temperature control (high limit fail safe device)
• UL® approved proportional integral (PI) digital controller • UL® approved incoloy sheath tubular heating elements

Shelving Design

Our angled welding rod storage shelving is purpose-built not to inhibit natural convection- a common occurrence with competing brands that utilize flat shelving for storage. The unique welded-in shelves allow the insertion of full 50 lb. tins of welding rods up to 18 inches which is a unique benefit for nuclear and aerospace welding codes that require immediate heated storage of opened tins before use.

Most electrode manufacturers discourage ‘stacking’ of electrodes too deeply while being heated to allow for better airflow over the consumable. With our shelving design, heat reaches the electrode coating more effectively to stave off atmospheric moisture. Please see diagram below of the airflow action with our shelving design:

Quality Insulation

Efficient heating design must be supported by quality insulation. The Keen KHT- 200 features features thermal mineral wool insulation. It is highly thermally- efficient and is installed within the walls and door of the unit.

Customization

We have the unmatched ability to customize any of our standard ovens, and/or design one-of-a-kind ovens for unique storage requirements. Welding codes are constantly changing, and Keen is ready to meet the demands of today’s welders. Please visit our website http://www.keenovens.com for more information about our products and detailed technical information about welding consumable storage.

Frequently Asked Questions

What are stick electrodes and what is shielded metal arc welding (SMAW)?

SMAW (Shielded Metal Arc Welding) is a manual arc welding process that is often called stick welding. It is one of the most popular welding processes used today. Its popularity is due to the versatility of the process and the simplicity and low cost of the equipment and operation. SMAW is commonly used with such materials as mild steel, cast iron, and stainless steel.

The process requires a consumable electrode that is coated in flux (stick rod) to lay the weld, and an electric current is used to create an electric arc between the electrode and the metals that are being welded together. The electric current may be either an alternating current or a direct current from a welding power supply. While the weld is being laid, the electrode’s flux coating disintegrates. This produces vapors that provide a shielding gas and a layer of slag. Both the gas and slag protect the weld pool from atmospheric contamination. The flux also serves to add scavengers, deoxidizers, and alloying elements to the weld metal.

What is the difference between welding electrode rebaking and welding electrode holding?

Generally, there are two processes involved with the proper maintenance of stick welding electrodes: holding (also called storing) and rebaking (also called reconditioning).

The holding process refers to the short-term* or long-term** heated storage of welding electrodes to maintain factory-fresh dryness. Storing the rods at elevated temperatures prevents atmospheric moisture contamination of the electrode’s hygroscopic flux coating. There are various temperature requirements according to the type of electrode and also that are also set forth by welding codes. For specific holding temperature guidelines, please contact the manufacturer of your consumable.

The rebaking process refers to the short-term*, high temperature heating of welding rods that have been or may have been contaminated by atmospheric moisture. The rebaking process “reconditions” the welding rod, meaning it bakes out the moisture that has entered the coating thus restoring the electrode so it is suitable for reuse. Many large shops have a rebake rod oven in the tool crib in which electrodes coming back from the field are procedurally rebaked as a precaution to remove any moisture, and then put into a holding oven for long term low temperature storage for reuse. For specific rebake temperature guidelines, please contact the manufacturer of your consumable.

* - In relation to our products, we consider short-term to mean 8 hours or less.

** - In relation to our products, we consider long-term to mean 24 hours/day 7 days/week.

Why do I need to store and/or rebake stick welding electrodes in a heated rod oven?

In stick welding (SMAW), the most commonly used welding electrode is low hydrogen 7018. It is covered with flux which is hygroscopic (easily absorbs moisture from the air). This flux coating burns and converts into a shielding gas that protects the weld pool from atmospheric contaminants such as hydrogen, nitrogen, oxygen and others. If these contaminants enter the weld pool they will cause defects such as cracking, and porosity (worm holes.) These defects can create a weak point at which the weld may fail under stress or load.

Low-hydrogen 7018 rods are just what their name states…low hydrogen. They allow very little hydrogen into the weld pool unless they have been stored improperly and contaminated by moisture. Moisture allows hydrogen into the flux, which is then introduced into the weld pool adversely. This moisture contamination is super-heated during the welding process, converts into steam and then bubbles up to the surface leaving an open pocket in the finished weld bead. So at that particular spot the weld is weaker because it is not a solid bead. This will happen at the beginning of the bead with each new rod used, and diminish as the rod heats up and burns the moisture out as it is being consumed. Moisture-contaminated rods may make a good-looking weld at first, but they will be subject to longitudinal cracking either right after welding, or later on (longitudinal cracking occurs where a crack begins at one point and follows the length of the weld).

How are KHT-200 rebake welding rod ovens used in the field?

As explained above, rebake SMAW rod ovens are designed to reach the high temperatures needed to restore dryness in the flux coating of low hydrogen SMAW electrodes that have been exposed to detrimental amounts of moisture. They are often centrally located within a facility where the storage and distribution of welding consumables is controlled. When electrodes are returned from the field, they are examined, and it is determined if they are to be put into a holding rod oven or redried at high temperatures in a rebake rod oven. Keen KHT-200 rebake SMAW rod ovens are large capacity units, and are the preferred choice for many large manufacturing, fabrication and aerospace facilities where tight control of welding electrode quality and cost is of utmost importance.

What can you tell me about performance of Keen KHT-200 rebake rod ovens?

The KHT-200 is ruggedly designed to withstand years of use in the most demanding industrial environments. Heavy-gauge steel is used throughout the unit and 4 inches of mineral wool in the oven walls and door keeps Keen KHT-200 SMAW rod ovens well-insulated and energy efficient. The exterior features a durable powder-coated paint that is highly-resistant to industrial environments and will stand up to years of use.

Thorough, energy-efficient and quick heating is the hallmark of all Keen welding electrode storage ovens. The KHT-200 rebake rod oven in particular has two 1000w incoloy sheath tubular heating elements placed in areas to facilitate natural convection and efficient heating.

As standard equipment, Keen KHT-200 rod ovens feature a UL® approved programmable proportional integral microprocessor-based controller with digital temperature adjustment and LED temperature-indicating display. The temperature reading can be displayed in either Fahrenheit or Celsius, and has a ±0.2 degree accuracy. Handy tactile increment/decrement keys on the controller’s water-resistant front panel enable easy temperature set point adjustment. The controller also features an on/off control mode. The standard control unit supplied with Keen KHT-200 rod ovens is programmable for standard operation, and an upgraded “ramp & soak” version is also available upon request.

Can you explain the purpose of angled shelves in the KHT-200 rebake welding rod oven?

Our angled welding rod storage shelving is purpose-built not to inhibit natural convection- a common occurrence with competing rod oven models that utilize flat shelving for storage. The unique welded-in shelves allow the insertion of full 50 lb. tins of welding rods up to 18 inches which is a unique benefit for nuclear and aerospace welding codes that require immediate heated storage of opened tins before use.

I would like a different shelving configuration. Can Keen offer a different type of shelf system for Keen KHT-200 rebake welding rod ovens?

Yes. For Keen customized industrial ovens, fabrication and design of shelving is specific to the customer’s process and can consist of flat perforated, removable, vertically adjustable, cradled, stackable baskets, trays and much more. Shelving in our line of welding consumable storage ovens is specific to the type of consumable being stored and storage capacity. We can produce a variety of configurations to enhance efficiency of your heat processing application.