Hello,everyone, could anybody explain to me the red line among the below interpretation? many thanks!
Interpretation: VIII-77-04
Subject: Section VIII, Division 1, UG-84(c)(5)(b), Table UG-84.1 and Table UG-84.2
Date Issued: January 18, 1977
File: NA
Question: Does the following meet the intent of the Code?
The material is SA-516, Grade 70 where the actual plate thickness is 0.262 in. The
minimum design temperature is -50°F and the Charpy impact specimen size is 10 x 5 mm. Since the
specimen width (0.197) is less than 80% of the actual plate thickness, what is the interpretation with regard
to the appropriate test temperature per Table UG-84.2 and with regard to the applicable Charpy V-notch
impact energy in foot-pounds per Table UG-84.1.
Reply: The provisions of the second sentence of UG-84(c)(5)(b) require that the test temperature
for the specimen in question is that which is adjusted by Table UG-84.2 for the temperature reduction
corresponding to the actual material thickness and the temperature reduction corresponding to the Charpy
specimen width actually tested. In this case the test temperature would be reduced by the temperature
reduction corresponding to the size of the specimen, 20°F, minus the temperature reduction corresponding
to the material thickness, 10°F, resulting in a temperature reduction of 10°F below the minimum design
temperature -50°F or a required test temperature of -60°F. The required energy in foot-pounds from Table
UG-84.1 is multiplied by 5/10 or the ratio of the actual specimen width along the notch to the width of a
full size specimen.

Hi Fred,
please find attached an example:

(1) Test temperature=MDMT-Temperatur reduction
and
(2) Temperature reduction= f(Charpy specimen width) –f(nominal material thickness)

Example:
MDMT=-20°C
Nominal tube thickness 7 mm.
Charpy specimen width after machining the tube 5 mm

For 5 mm charpy specimen width, find 11 °C temperature reduction in table UG-84.2.
For 7 mm material thickness, find 4°C temperature reduction in table UG-84.2.

(2) Temperature reduction= 11-4= 7°C
(1) Test temperature= -20°C-7°C=-27°C

Hope that helps

_________________
Kind regards,
Juergen Fleischfresser

thanks! your example is helpful, it is very clear!