CVN temperature Requirement

[Rems Okonkwo]

Dear All,

 

Can someone please explain the ASME B31.3 requirement with respect to Stardard Subsize CVN specimen requirement.

 

I have a 2inches pipe with thickness of 5.5mm. the design temparature is -46deg C

 

what will be my test temperature for this test coupon as describe in B31.3 below.

 

 

ASME B31.3

323.3.4 Test Temperatures

(b) For Materials With Thickness Less Than 10 mm

(0.394 in.).

Where the largest attainable Charpy V-notch

specimen has a width along the notch of at least 80%

of the material thickness, the Charpy test of such a specimen

shall be conducted at a temperature not higher than

the design minimum temperature. Where the largest

possible test specimen has a width along the notch of

less than 80% of the material thickness, the test shall

be conducted at a temperature lower than the design

minimum temperature by an amount equal to the difference

(referring to Table 323.3.4) between the temperature

reduction corresponding to the actual material thickness

and the temperature reduction corresponding to the

Charpy specimen width actually tested

 

Regards,

Rems O

[Sasikumar Nair]

Dear Rems,

Pls. check the size of "largest attainable Charpy V-notch specimen" out of this coupon,  after that we can determine the test temperature.

Regards,

Sasi.

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[Rems Okonkwo]

Dear Sasi,

the maximum attainable specimen shall be 4mm.

regards,

rems

[perumal govindan]

Dear Mr. Rems O,

With reference to your email, if test coupon thickness is 5.5mm and Charpy Impact Design Test Temperature is -46 degree centigrade, then your test specimen size for impact size will be 80% of 5.5 mm = 4.4 mm or 4 mm and corresponding impact test temperature will be  -46 deg.C - 16.7 deg. C (as per ASME B31.3:2004 Table 323.3.4 reduction of temperature is 16.7 deg. C) = -62.7 deg.C( minus 62.7 Deg.C).

And if the impact test specimen size of 4 mm is not attainable, the impact test specimen size will be 3.3 mm and corresponding test temp. will be -46 deg.C -19.4 deg. C= -65.4 deg. C ( minus 65.4 Deg.C).

Hope this clarifies..........

P Govindan

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[perumal govindan]

Dear Mr. Rems,

If the impact test coupon size is 4 mm, then the impact test temp. will be -62.7 deg C (minus 62.7 deg.C)

P Govindan

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[Sasikumar Nair]

Dear Rems,

Impact test temperature for this specimen will be minus 46 deg.C + minus 8.4 deg. C = minus 54.4 deg.C

[Pls. ref: Table 323.3.4, for 5.5mm, say 6mm =reduction required is minus 8.3 deg.C and for 4mm 16.7deg.C, so minus16.7deg.C - minus8.3.deg.C =minus8.4deg.C, hence minus 46deg.C + minus 8.4deg.C = minus54.4deg.C]

Regards,

Sasi.