What is the pre-stretch amount of the compensator?
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“The pre-stretch distance of the compensator can be determined by measuring the distance between the last weld seam after it has been installed, before welding that seam; this value should correspond to the specified pre-stretch amount. How is the pre-stretch amount calculated?
The pre-stretch amount is an empirical value, not calculated.
Is cold drawing necessary because the amount of compensation is insufficient? The power pipeline design manual states that for temperatures below 250 degrees, the pre-stretch amount is 50% of the thermal expansion amount; whereas for temperatures between 250 and 400 degrees, the pre-stretch amount is 70% of the thermal expansion amount. Could it be that pre-stretching is necessary because the compensation amount is insufficient?