| 摘要 |
PROBLEM TO BE SOLVED: To provide a protective covering of a weld zone of an embedded steel pipe which is the covering for protecting the weld zone of the embedded steel pipe subjected to electrolytic protection by an external power source system and is formed by heating heat shrinkable tube to cover welding part and the right and left ends of the steel pipe corrosion preventive covering part near the weld zone and bringing the tube into tight contact with the steel pipe, winding biodegradable resin foamed sheets and plastic nets around the top thereof and tightening the entire part of the covering with plural retaining tapes. SOLUTION: Since the biodegradable resin foamed sheets exist in-between of the weld zone protective covering, the damage of the covering by soil and sand does not occur in backfilling into the ground. On the other hand, the biodegradable resin foamed sheets disappear in about one year but the soil stabilizes after lapse of one year and there is no more movement of the sand and soil, and there is no more flawing of the covering. Even if water stagnates temporarily at the point of the covering, the covering is the net and therefore the water is automatically discharged from the mesh of the net and the effect of the electrolytic protection may be retained without degradation.
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