Hey all, I'm currently in the process of design a piping specification for use on C02 transport trailers. the minimum working temperature needs to be -57°c (below the triple point) and max temp of 38°C. with a MAWP of 450PSI. We would like to use A106B pipe and A-105N fittings, knowing that we have to reduce the allowable working temperatures beyond table 323.2.2A (-29°c for both matl) this would then stick us over to the exemption process ideally. so as far as I can tell, Table 232.2.2(B-3) says that if we meet note 3 or 4 we can be exempted. We are going to try and meet note 3 which refers to section 323.2.2(g)-(i). My confusion comes in here at 323.2.2(g) and (h). it states in (g) that I can go down to -104°C if my stress ratio is 0.3 or less (which it is) but then (i) states that I can only go down to -48°C. is the differentiator the specific "carbon, low alloy, and intermediate alloy steel materials" stated in 323.2.2(h) vs just "steels" from 323.2.2(g) which refers to all types of steels ie. stainless, carbon etc.?
they are as follows.
B31.3 323.2.2
(g) For steels, impact testing is not required for material
(including welds) if the stress ratio as defined in (b) is
0.3 or less, the design minimum temperature is warmer
than or equal to −104°C (−155°F), and when (c) applies.
(h) For carbon, low alloy, and intermediate alloy steel
materials (including welds) that have not been qualified
by impact testing, the minimum temperature from
Table A-1, Table A-1M, or Figure 323.2.2A may be
reduced to a temperature no colder than −48°C
(−55°F) by the temperature reduction provided in
Figure 323.2.2B when (c) applies. For carbon, low
alloy, and intermediate alloy steel welds that require
impact testing in accordance with Table 323.2.2, Box
A-3(b), the temperature reduction from Figure
323.2.2B shall be applied to −29°C (−20°F).
(i) For carbon, low alloy, and intermediate alloy steel
materials (including welds) that have been qualified by
impact testing, the permitted design minimum temperature
may be reduced to a temperature no colder than
−104°C (−155°F) by the temperature reduction from
Figure 323.2.2B when (c) applies.
In summary, is (g) the blanket statement with (h) & (i) adding clarification. Thus setting the coldest allowable temperature for carbon steels to be -48°C before impact testing is mandatory.
looking forward to gaining some insight.
thanks,
they are as follows.
B31.3 323.2.2
(g) For steels, impact testing is not required for material
(including welds) if the stress ratio as defined in (b) is
0.3 or less, the design minimum temperature is warmer
than or equal to −104°C (−155°F), and when (c) applies.
(h) For carbon, low alloy, and intermediate alloy steel
materials (including welds) that have not been qualified
by impact testing, the minimum temperature from
Table A-1, Table A-1M, or Figure 323.2.2A may be
reduced to a temperature no colder than −48°C
(−55°F) by the temperature reduction provided in
Figure 323.2.2B when (c) applies. For carbon, low
alloy, and intermediate alloy steel welds that require
impact testing in accordance with Table 323.2.2, Box
A-3(b), the temperature reduction from Figure
323.2.2B shall be applied to −29°C (−20°F).
(i) For carbon, low alloy, and intermediate alloy steel
materials (including welds) that have been qualified by
impact testing, the permitted design minimum temperature
may be reduced to a temperature no colder than
−104°C (−155°F) by the temperature reduction from
Figure 323.2.2B when (c) applies.
In summary, is (g) the blanket statement with (h) & (i) adding clarification. Thus setting the coldest allowable temperature for carbon steels to be -48°C before impact testing is mandatory.
looking forward to gaining some insight.
thanks,
