In standards DL 438-2000 and DL/T 439-2006

the supervision and inspection of high-temperature fasteners after putting them into service all had been stipulated.It is discovered from analysis of both standards that the stipulation in DL 438-2000 is easy to make the supervisor or inspector to regard the hardness as only one index for judging the damage of bolts

but in DL/T 439-2006

it is insisted to use several indices in supervisory process of bolts for comprehensive evaluation

therefore

being more scientific and practicable.For this

it is recommented that the related departments have to unify the requirements for inspecting bolts as far as possible in the two above-mentioned supervision and inspection modes.