Final answer:
The recommended repair method for a dented steel structural tube is cold working.
Step-by-step explanation:
When a steel structural tube is dented to more than 1/4 of its circumference, the recommended repair method is cold working. Cold working refers to the process of reshaping or restoring the damaged tube without the need for heat. It involves using specialized tools or machines to gradually remove the dent and restore the tube to its original shape.
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