Carbon steel pipes at low temperatures

[amateurpipe]

Hi,



I have a situation where the plant construction has been completed and after that it is realized that certain carbon steel pipes will carry a fluid at - 57 °C temperature.

So, I am trying to work a way out to justify the use of carbon steel pipes at these low temperatures without any further impact tests at this stage.


The carbon steel pipes used are :


A333 Gr. B (8”, 8.18 mm thk - Min Design Temp from Table A-1 = - 45.5 deg C ) &

ASEM 671 CC60 ( 28”, 9.53 mm thk - Min Design Temp from Table A-1 & Fig 323.2.2A = - 48 deg ).

Para. 323.2.2(d)(1), limits the use of Figure 323.2.2(b) to fluid temperatures at - 48 °C.

So, use of both the above mentioned pipes cannot justified by invoking Para. 323.2.2(d)(1) as the fluid temperature is - 57 °C

We will have to invoke Para. 323.2.2(d)(2).


Will satisfying condition ( Note (3) of Table 323.2.2 ) in Para. 323.2.2(d)(2) justify the use of these pipes at - 57 °C without any further impact test ( now that the construction is completed ) ?

For the carbon steel pipes at temperatures of - 48 °C and above , if conditions in Para. 323.2.2(d)(2) are satisfied, can these pipes be used ( without impact testing for base metal, weld deposits, and HAZ ( other that the impact testing already done by the pipe manufacturer )) without satisfying the conditions (a) & (b) of Para. 323.2.2(d)(1) ( conditions for hydrotest pressure & pipe thickness )?

If the conditions in para. 323.2.2(d)(1) ( for temperatures at or above - 48°C ) or para. 323.2.2(d)(2) (for temperatures between - 29°C to - 104°C ) are satisfied, can the conditions in para. 323.2.2(c) ( Column B of Table 323.2.2 ) be ignored to justify use of carbon steel pipes without impact testing for base metal, weld deposits, and HAZ ( other that the impact testing already done by the pipe manufacturer ) ?

Thanks in advance....

amateurpipe

 

[amateurpipe]

Kindly help in this matter....

I have tried to find a solution from many people, but could not arrive at an answer.

 

[metengr]

amateurpipe;
To summarize, you are looking for an exemption to impact testing the aforementioned material based on the requirements in 323.2.2 of B31.3.

Using Table 323.2.2 and Column B-3, use of stated materials at MDMT below the assigned curve is permitted by Notes 2 and 3 of Figure 323.2A.

Since your MDMT falls below Curve D of Figure 323.2A, Note 4 would apply. This Note takes you to Table 323.2.2 taking advantage of the stress ratio.

If the stress ratio further reduces the MDMT to get you where you need to be, you need to go back to 323.2.2 (d)1 and follow the requirements for (d) (1) (a) and (b).