小直径油管
small diameter coiled tubing
带切线直管段的三倍直径弯头
three-diameter ells with tangents
林分直径分布规律
regularity of diameter structure of stands
小直径管道
small diameter pipeline
small diameter pipe
Pipes with small diameters
小直径管供热系统
small bore heating system
小直径管坯
Small-sized billet for tube-making
无底柱小分段崩落采矿法
non-sill pillar little segment caving method