§215.TABLE C. Minimum Material Requirements for Shells and Bottoms of Refrigerated Storage Tanks for Various Temperatures and Thicknesses

Design Temperature	Thickness	Material Spec.	Qualifications to be Added to the Basic Specification
65 F to 25 F, incl. (See Note 1)	Up to ½", incl.	Any approved steel with specified min. T.S. not exceeding 60,000 psi	None
	Over ½" to 1", incl.	A-131B (or C)	None
		Case 1256	None
		A-201 A & B	FGP (Fine grain practice)
	Over 1" to 1⅜", incl.	A-131C, Case 1256-	None
		A-201 A & B	None
			FGP
.
	Over 1⅜"	A-131C	Normalized
		Case 1256	Normalized
		A-201 A & B	FGP, Normalized
Below 25 F to 5 F, incl. (See Note 2)	Up to ½", incl.	Case 1256	None
		A-201 A & B	None
	Over ½" to 1⅜ ", incl.	A-131B (to 1" max.)	FGP
		A-131C	FGP
		Case 1256	FGP
		A-201 A & B (to 1" max)	FGP, High Mang.*
		A-201 A & B (over 1")	FGP, High Mang., Normalized
	Over 1⅜ "	A-131C	Normalized
		Case 1256	Normalized
		A-201 A & B	FGP, High Mang., Normalized
Below -5F to -30F (See Note 3)	Up to ½" incl.	Case 1256	FGP
		A-201 A & B	FGP, High Mang.
	Over ½" to 1⅜" incl.	A-131B (to 1" max)	FGP, Normalized
		A-131C	Normalized
		Case 1256	FGP, Normalized
		A-201 A & B	FGP, High Mang., Normalized
	Over 1⅜"	A-300 Class 1	A-201 A & B only

 

*Manganese content of 0.70% to 1.0% is preferred in lieu of usual content of 0.80% maximum.

 

Note 1:    The design temperature shall be taken as the lower of the following:

 

a)     The minimum temperature to which the tank contents will be refrigerated.

 

b)     The minimum estimated tank shell temperature due to atmospheric temperatures, considering the effectiveness of the insulation in keeping shell temperatures above expected minimum atmospheric temperature (if expected to be below the refrigerated temperature).

 

Note 2:  For this thickness, temperature category approved steels include all those listed in API 12-C and API 620.  Materials for vessels must comply with requirements of the Code and any additional requirements of this table. A-131 steel is not approved by ASME and some Code cases have not been approved by local jurisdictions.  All specific materials listed in table are satisfactory for all designs based on API 12-C or API 620.

 

Note 3:  For vessels constructed under the Code with a design temperature below -20F., the impact requirements shall comply with 8 Ill. Adm. Code Section 215.Table B.