"Sweating occurs during the hydrostatic test" 或 "There is sweating during the hydrostatic pressure test" 都可以表达“水压试验时出汗”这一意思。其中,“hydrostatic test”或“hydrostatic pressure test”均指水压试验,“sweating”形象地描述了出汗这一现象。根据具体语境和表达习惯,可以选择更合适的表述。