对于P 8材料，一般不需要预热，关于正确的预热和层间温度的要求，参见相应的WPS。
No preheating is required for P8 material in general. For the correct preheating and interpass temperatures, please refer to corresponding WPS.
根据FWEC管式空气预热器技术规范对管子—管板胀接的要求，对有缝电阻焊管胀接进行工艺试验。
In this paper, to meet the expending requirements of technical specification for FWEC Tubular Air Heaters, the expending procedure test for the ERW tube was performed.
但由于室外温度比较低，要求预热到室温后再进行焊接操作的焊前预热可不作记录。
However, if outdoor temperature is comparatively low, the records preheating aren't required for the welding operation preheating to room temperature.
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