[MW:718] Impact test exemtions as per Fig UCS66.1

members please share your views, also i am giving here my
understanding

i have a job where MDMT is -47 deg.C and -49deg.C, however the
materials are available with impact testing at -45 deg.C only

Ratio = (Required calculated thickness x E*) / (Actual thickness less
corrosion and any thinning allowances)

my understanding is once we calculate coincident ration by the formula
given above, one need to interpolate this ration (ofcourse it must be
below 1) to find out the differential temperature

for. e.g if i get ratio 0.5 i get an interpolated value of 32 deg.c
differnetial temperature
then i can use this material for upto (-45 + -32 = -77 deg.C) without
impact tetsing.

please correct me if my interpretation is wrong! and share your views?

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