Why is it advisable to backfill pipelines during the coldest period of the day and night?
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This post was last edited by Sammy_Wang on 2016-10-27 08:10. Why, according to clause 4.5.11 of GB50268-2008, should backfilling of flexibly connected pipes be carried out during the period of lowest temperatures in a day? Why? Was the standard written wrong?
The pipe should contract, so the filler can be made more compact.
It’s 50235, right? 50236 is the welding specification
It’s 50268, I made a mistake. Sorry
It is better to let the pipeline be under pressure due to temperature changes rather than under tension; the closing of large bridges in construction projects follows the same principle
If you think about whether ordinary materials have good compressive strength or good tensile strength, you’ll understand; it has little to do with being compacted
I hope the expert can explain it more clearly; I still don’t quite understand it
The compressive strength of ordinary materials is much greater than their tensile strength; therefore, mechanical tests on materials usually involve tension testing. The lowest temperature during the day means that when the pipes are in use, there is a higher likelihood that they will be in a compressed state compared to when they are buried at the highest temperatures
The lowest temperature of the day means that the pipes are shorter at that time; as the temperature rises, the pipes expand. And if the pipes are fixed, is it pressure rather than tension that acts on them in the length direction? In the case of metal materials, why are mechanical tests always conducted as tensile tests rather than compressive tests? This is because materials generally have much greater compressive strength than tensile strength; isn’t it more reliable to subject the material to compression rather than tension? Search for the temperature at which the bridge is closed; it’s the same principle