(1) Yes, but read Subsection C UCS 66-68 in ASME VIII D. 1 thoroughly.
(2) My initial thought would be that austenitic stainless steel might be a better fit if it is an exchanger, depending on other things like chlorides...
It depends on design thickness, which was not supplied. Read Section VIII, Div 1 carefully to determine if this material can be used. At a minimum, impact testing will be required at this minimum design metal temperature. You might be using 9% Ni alloy to achieve the necessary impact requirement.
Please take a look at ASME Sec-II,Pt-A, SA-20, Table A 1.15. As per this table under Class-IV materials, (with an acceptable impact values of 15Ft-Lbs Average & 12Ft-Lbs Minm):-
-SA-516/70,the recommended impact test temp, up to 1 inch thk:- -50 Deg F
-SA-203Gr B,the recommended impact test temp, up to 1 inch thk:- -90 Deg F(2.5% Nickel)
-SA-203Gr E,the recommended impact test temp, up to 1 inch thk:- -150 Deg F(3.5% Nickel)
For the design temp specified above SA 203Gr B should be a good fit.
Should there be any sour/wet H2S service requirements be applicable(refinning or petrochemicals),the requirements of NACE MR -0103 should be met.If the intended service is for upstream oil and gas production(where MR0175 requirements are commonly applicable) 2.5% & 3.5% Nickel steels are not acceptable as per the current acceptance standards.