重点介绍了DL/T 438—2009中取消合金钢碳化物、蠕变孔洞检测监督、蒸汽管道不强制进行蠕胀检测的技术背景和9%~12%Cr钢制高温部件硬度控制的技术依据，阐述重要技术条款的修订项，以利于规程的解读和执行。

For the convenience of understanding and performing the codes, the technical background for canceling carbides and creep voids check of alloy steel, and for unenforced creep strain check of steam pipe at high temperature are emphatically introduced. The technical basis for control the hardness of 9%~12%Cr steel used in high temperature assemblies is analyzed. Furthermore, the revise of some important technical terms is demonstrated.