Does MDMT can be lower than the impact test temperature indicated in AMSE code?

[mechengineer]

Hi material and inspection experts,

SA-765 grade IV, impact test temperature is -30 deg.C in Tabel 3, ASME II, part A.
The vessel manufacturer told us that as per 6.6.1, they can do impact test for -46 deg.C.
<6.1.1 When agreed upon between the purchaser and the
producer and specified on the order, impact tests may be made
at temperatures different from those shown in Table 3 provided
the test temperature is at least as low as the intended service
temperatures and the provided impact energy requirements of
Table 3 are met. Such forgings shall be suitably marked in
accordance with 9.1 to identify the test temperature>
Q1, what is the minus tolerance of test temperature in code or in engineering practice?
Q2, Whether it is possible for doing the test with -46 deg.C for SA-765 grade IV, or whether is acctepable if the manfaturer provides us the test report for -46 deg.C?

My understanding is that the impact test temperature in code is based on the material toughness of specimen test data and engineering practice/experience. Code requirement shall be cosidered as the minimum. Test temperature may be higher than Table 3 as per 6.1.1, but not allow lower than code in general engineering pactice.

Thanks

 

[r6155]

The MANUFACTURER can do impact test at -31C, -35C ,-40C.. etc., but not -29C, -20C ...etc
Read again Table 3

 

[goutam_freelance]

Test temperature may be higher than Table 3 as per 6.1.1, but not allow lower than code in general engineering pactice.

As per cl. 6.1.1, the test temperature can be different from those in Table 3, so it can be lower too. But the impact energy values shall not be inferior to values in Table 3.

As per clause 3.1.3, the impact test temperature needs to be specified along with the order.

 

[r6155]

goutam..said
As per clause 3.1.3, the impact test temperature needs to be specified along with the order

INCORRECT
Clause 3.1.3 does not exist. See clause 3.2
Also see table 3: If no temperature is specified, test will be at test temperature shown in this table.

 

[goutam_freelance]

@mechengineer
Pl check the latest code.My code is not latest.
However old code requirements are not wrong.

 

[r6155]

It is not good practice to work with old codes.

 

[goutam_freelance]

But it was a good practice to follow the same code some time ago.

 

[mechengineer]

The MANUFACTURER can do impact test at -31C, -35C ,-40C.. etc., but not -29C, -20C ...etc
Read again Table 3

Please read and understand the original post and Table 3 carefully and correctly. The discusssion is for grade IV of AS-765 only, not other grade in Table 3 as you mentioned

 

[r6155]

@ mechengineer

You've never witnessed an impact test, this is why you can't understand this test (Charpy) and need to open a post.

You said: "The vessel manufacturer told us that as per 6.6.1, they can do impact test for -46 deg.C".
6.6.1.???? what??'

You said:" Test temperature may be higher than Table 3 as per 6.1.1, but not allow lower than code in general engineering practice".
What??.
It's the opposite: test temperature may be LOWER (colder) than Table 3

Once again you are confused.

Regards