419 Please explain the method of field test and flushing (blowing off )of the pipelines.
419 Please explain the method of field test and flushing (blowing off )of the pipelines.
请说明管线的现场试验和冲洗（吹净）方法。
419 Please explain the method of field test and flushing (blowing off )of the pipelines.
请说明管线的现场试验和冲洗（吹净）方法。