无约束补偿器，也称为自由补偿器，是一种在管道系统中用于消除或减少由于热膨胀、收缩、振动等因素引起的应力和变形的装置。其主要作用如下：
1. 防止管道应力过大：在管道运行过程中，由于温度变化、介质流动等因素，管道会产生热膨胀或收缩。若管道应力过大，可能会导致管道变形、泄漏甚至破裂。无约束补偿器能够有效吸收管道的热膨胀或收缩，防止管道应力过大。
2. 提高管道使用寿命：管道在使用过程中，由于应力和变形的影响，容易产生疲劳裂纹。无约束补偿器能够降低管道应力，减少疲劳裂纹的产生，从而提高管道的使用寿命。
3. 保证管道安全运行：管道在运行过程中，由于应力和变形的影响，可能会产生振动。无约束补偿器能够有效吸收管道振动，保证管道安全运行。
4. 减少维修成本：管道在运行过程中，由于应力和变形的影响，容易产生泄漏、破裂等问题。无约束补偿器能够降低管道应力，减少维修成本。
下面是一张图，展示了管道补偿原理：
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| 管道段1 |–| 管道段2 |
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