TMU – 21U
Permissible spatial positions during welding
TMU – 21U Welding Electrodes
Electrodes for welding of carbon and low alloy steels
Prices for welding electrodes
Type of coverage
Basic. It provides a seam metal with high resistance to the formation of crystallization cracks and low hydrogen content.
Current and polarity
Direct current of reverse polarity (DC+)
Surfacing coefficient
9.0 – 9.5 g/ah
Consumption of electrodes
~ 1.5 kg per 1 kg of deposited metal
Application Area. TMU – 21U Welding Electrodes.
Designed for welding critical metal structures, pipelines, pipes, and other pipe elements made of carbon and low-alloy structural steels in all spatial weld positions except vertical “top-to-bottom”, with direct current of reverse polarity.
Welding Technique. TMU – 21U Welding Electrodes.
Welding is performed with a short and extremely short arc length at a voltage of 24-25 V, which provides higher arc thermal power. Short-term arc lengthening without porosity formation is possible.
It is recommended to perform welding on thoroughly cleaned edges. When welding root passes of pipes without backing rings, welding is performed in the groove ensuring full penetration.
Regulatory Documents. TMU – 21U Welding Electrodes.
GOST 9466-75, GOST 9467-75.
Corresponding International Standard.
E 513 – B30.
Special Properties. TMU – 21U Welding Electrodes.
The electrodes have high arc stability and easy arc striking. They allow short-term arc lengthening without porosity formation. They have better slag detachability when welding in a groove compared to UONI 13/55 -7. Unique feature: they allow welding in a narrow groove with a total bevel angle of 15°.
Thanks to the high penetrating ability of the arc, they ensure complete fusion of the edges at the groove root and the formation of a back bead, which eliminates the need for backing rings.
Chemical Composition of Deposited Metal, %
| C | Si | Mn | P | S | |
| Minimum | 0.08 | 0.20 | 0.70 | 0.000 | 0.000 |
| Maximum | 0.10 | 0.40 | 1.00 | 0.030 | 0.030 |
Welding Recommendations (Current, A)
| Diameter, mm | Weld Position | ||
| Flat | Vertical | Overhead | |
| 3.0 | 80-110 | 60-90 | 60-90 |
| 4.0 | 130-170 | 100-140 | 100-140 |
| 5.0 | 170-200 | 140-160 | 140-160 |
We respond quickly to questions on Telegram
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Bottom horizontal or in a boat
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Bottom to the corner
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Horizontal seam on a vertical plane
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Vertical seam for lifting
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Vertical seam for descent
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Ceiling seam
All covered electrodes are sensitive to moisture absorption. Excessive moisture content in the coating can lead to porosity or hydrogen cracking.
However, if the climatic storage conditions meet the following requirements, moisture absorption by the electrodes is minimal:
• 5–15°C at a maximum relative humidity of 60%
• 15–25°C at a maximum relative humidity of 50%
• >25°C at a maximum relative humidity of 40%
At lower temperatures, maintaining the storage temperature 10°C above the ambient temperature is sufficient to achieve the required moisture content level. Cold packages must be allowed to warm up to ambient temperature before opening.
At higher temperatures, the required moisture content in the air can be achieved by dehumidification. The shelf life of electrodes under the above conditions shall not exceed three years.
• Covered electrodes with a basic coating and low hydrogen content must be baked prior to each use whenever requirements regarding the content of diffusible hydrogen and/or the soundness of the deposited metal are specified.
• Stainless steel electrodes with a basic coating may produce porosity during welding if the humidity levels during their storage did not meet the requirements. To restore their original properties, they also need to be baked.
• Electrodes for welding carbon steels with a cellulosic or rutile coating typically do not require baking.
• Electrodes that have suffered serious damage due to exposure to moisture cannot be restored by rebaking and must be rejected.
Contacts
Company phone numbers:
+375 (29) 688-27-06
+375 (17) 388-28-02 accountant
+375 (17) 388-28-03 sales department
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