ASME VIII-1 MDMT exemption for SB 163 N08825

[FPPE]

Hi,

According to UG-20(f):

"Impact testing per UG-84 is not mandatory for pressure
vessel materials that satisfy all of the following:
(1) The material shall be limited to P‐No. 1, Gr. No. 1
or 2, and the thickness, as defined in UCS-66(a) [see also
Note (1) in Figure UCS-66.2], shall not exceed that given
in (-a) or (-b) below:
(-a) 1/2 in. (13 mm) for materials listed in Curve A
of Figure UCS-66 (Figure UCS-66M);
(-b) 1 in. (25 mm) for materials listed in Curve B,
C, or D of Figure UCS-66 (Figure UCS-66M).
(2) The completed vessel shall be hydrostatically
tested per UG-99(b) or UG-99(c) or 27-4. Alternatively,
the completed vessel may be pneumatically tested in accordance
with 35-6.
(3) Design temperature is no warmer than 650°F
(345°C) nor colder than −20°F (−29°C). Occasional operating
temperatures colder than −20°F (−29°C) are acceptable
when due to lower seasonal atmospheric
temperature.
(4) The thermal or mechanical shock loadings are not
a controlling design requirement. (See UG-22.)
(5) Cyclical loading is not a controlling design requirement.
(See UG-22.)"

Exchanger tubes material SB 163 N08825 (thickness 1.65 mm) does not fall under these paragraphs, nor does under UCS-66, which only applies to carbon and low alloy steels.

Can we obtain for this material an exemption from impact test according to Div.1?

Thanks in advance

 

[SnTMan]

See Part UNF

Regards

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[FPPE]

Hi SnTMan,

From the following paragraph:

"UNF-65 LOW TEMPERATURE OPERATION
The materials listed in Tables UNF-23.1 through
UNF-23.5, together with deposited weld metal within
the range of composition for material in that Table, do
not undergo a marked drop in impact resistance at subzero
temperature. Therefore, no additional requirements
are specified for wrought aluminum alloys when they are
used at temperatures down to −452°F (−269°C); for copper
and copper alloys, nickel and nickel alloys, and cast
aluminum alloys when they are used at temperatures
down to −325°F (−198°C)"

I have understood that up to a required MDMT of -198°C, we are exempt from the code requirements of impact test for SB 163 N08825. Right?

Thank you

 

[SnTMan]

FPPE, I read it as your tubes are exempt from impact test at -198C and warmer. Your language "up to a required MDMT of -198°C," seems ambiguous to me

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[FPPE]

SnTMan, you're right, I meant from -198°C and above we are exempt. Thank you