Thickness of shells under internal pressure for Cylindrical Shells

General requirements

G1 - To these stress values a casting quality factor as specified in PG–25 of Section I; UG–24 of Section VIII, Division 1; or TM–190 of Section XII shall be applied.
G2 - These stress values include a joint efficiency factor of 0.60.
G3 - These stress values include a joint efficiency factor of 0.85.
G4 - For Section I applications, these stresses apply when used for boiler, water wall, superheater, and economizer tubes that are enclosed within a setting. A joint efficiency factor of 0.85 is included in values above 450°C.
G5 - Due to the relatively low yield strength of these materials, these higher stress values were established at temperatures where the shorttime tensile properties govern to permit the use of these alloys where slightly greater deformation is acceptable. The stress values in this range exceed 66²/₃% but do not exceed 90% of the yield strength at temperature. Use of these stresses may result in dimensional changes due to permanent strain. These stress values are not recommended for the flanges of gasketed joints or other applications where slight amounts of distortion can cause leakage or malfunction. For Section III applications, Table Y–2 lists multiplying factors that, when applied to the yield strength values shown in Table Y–1, will give allowable stress values that will result in lower levels of permanent strain.
G6 - Creep–fatigue, thermal ratcheting, and environmental effects are increasingly significant failure modes at temperatures in excess of 825°C and shall be considered in the design.
G7 - For Section VIII applications, these stress values are based on expected minimum values of 310 MPa tensile strength and yield strength of 140 MPa resulting from loss of strength due to thermal treatment required for the glass coating operation. UG–85 does not apply.
G8 - These stress values are established from a consideration of strength only and will be satisfactory for average service. For bolted joints where freedom from leakage over a long period of time without retightening is required, lower stress values may be necessary as determined from the flexibility of the flange and bolts and corresponding relaxation properties.
G9 - For Section III applications, the use of these materials shall be limited to materials for tanks covered in Subsections NC and ND, component supports, and for nonpressure–retaining attachments (NC/ND–2190).
G10 - Upon prolonged exposure to temperatures above 425°C, the carbide phase of carbon steel may be converted to graphite. See Nonmandatory Appendix A, A–201 and A–202.
G11 - Upon prolonged exposure to temperatures above 475°C, the carbide phase of carbon–molybdenum steel may be converted to graphite. See Nonmandatory Appendix A, A–201 and A–202.
G12 - At temperatures above 550°C, these stress values apply only when the carbon is 0.04% or higher on heat analysis.
G13 - These stress values at 575°C and above shall be used only when the grain size is ASTM No. 6 or coarser.
G14 - These stress values shall be used when the grain size is not determined or is determined to be finer than ASTM No. 6.
G15 - For Section I applications, use is limited to stays as defined in PG–13 except as permitted by PG–11.
G16 - For Section III Class 3 applications, these S values do not include a casting quality factor. Statically and centrifugally cast products meeting the requirements of NC–2570 shall receive a casting quality factor of 1.00.
G17 - For Section III Class 3 applications, statically and centrifugally cast products meeting the requirements of NC–2571(a) and (b), and cast pipe fittings, pumps, and valves with inlet piping connections of DN 50 and less, shall receive a casting quality factor of 1.00. Other casting quality factors shall be in accordance with the following:
(a) for visual examination, 0.80
(b) for magnetic particle examination, 0.85
(c) for liquid penetrant examination, 0.85
(d) for radiography, 1.00
(e) for ultrasonic examination, 1.00
(f) for magnetic particle or liquid penetrant plus ultrasonic examination or radiography, 1.00
G18 - See Table Y–1 for yield strength values as a function of thickness over this range. Allowable stresses are independent of yield strength in this thickness range.
G19 - This steel may be expected to develop embrittlement after service at moderately elevated temperature. See Nonmandatory Appendix A, A–207 and A–208.
G20 - These stresses are based on weld metal properties.
G21 - For Section I, use is limited to PEB–5.3. See PG–5.5 for cautionary note.
G22 - For Section I applications, use of external pressure charts for material in the form of bar stock is permitted for stiffening rings only.
G23 - For temperatures above the maximum temperature shown on the external pressure chart for this material, Figure CS–2 may be used for the design using this material.
G24 - A factor of 0.85 has been applied in arriving at the maximum allowable stress values in tension for this material. Divide tabulated values by 0.85 for maximum allowable longitudinal tensile stress.
G25 - For Section III applications, for both Class 2 and Class 3, the completed vessel after final heat treatment shall be examined by the ultrasonic method in accordance with NB–2542 except that angle beam examination in both the circumferential and the axial directions may be performed in lieu of the straight beam examination in the axial direction. The tensile strength shall not exceed 860 MPa.
G26 - Material that conforms to Class 10, 11, or 12 is not permitted.
G27 - Material that conforms to Class 11 or 12 is not permitted.
G28 - Supplementary Requirement S15 of SA–781, Alternate Mechanical Test Coupons and Specimen Locations for Castings, is mandatory.
G29 - For Section III applications, impact testing in accordance with the requirements of NC–2300 is required for Class 2 components and in accordance with ND–2300 for Class 3 components.
G30 - These stresses apply to all product forms (C, H, and P) as defined in SA/EN 10028–7.
G31 - The allowable stress value given for 250°C can be used up to the temperature of 260°C.
G32 - The allowable stress value given for 200°C can be used up to the temperature of 204°C.

Heat treatment requirements

H1 - For temperatures above 550°C, these stress values may be used only if the material is heat treated by heating to the minimum temperature specified in the material specification, but not lower than 1040°C, and quenching in water or rapidly cooling by other means.
H2 - For temperatures above 550°C, these stress values may be used only if the material is heat treated by heating to a minimum temperature of 1095°C, and quenching in water or rapidly cooling by other means.
H3 - Quenched and tempered at 650°C.
H4 - Solution treated and quenched.
H5 - For Section III applications, if heat treatment is performed after forming or fabrication, it shall be performed at 825°C to 1000°C for a period of time not to exceed 10 min at temperature, followed by rapid cooling.
H6 - Material shall be solution annealed at 1100°C to 1170°C, followed by a rapid cooling in water or air.

Size requirements

S1 - For Section I applications, stress values at temperatures of 450°C and above are permissible but, except for tubular products 75 mm O.D. or less enclosed within the boiler setting, use of these materials at these temperatures is not current practice.
S2 - For Section I applications, stress values at temperatures of 475°C and above are permissible but, except for tubular products 75 mm O.D. or less enclosed within the boiler setting, use of these materials at these temperatures is not current practice.
S3 - For Section I applications, stress values at temperatures of 550°C and above are permissible but, except for tubular products 75 mm O.D. or less enclosed within the boiler setting, use of these materials at these temperatures is not current practice.
S4 - For Section I applications, stress values at temperatures of 625°C and above are permissible but, except for tubular products 75 mm O.D. or less enclosed within the boiler setting, use of these materials at these temperatures is not current practice.
S5 - Material that conforms to Class 10, 11, or 12 is not permitted when the nominal thickness of the material exceeds 19 mm.
S6 - Material that conforms to Class 10, 11, or 12 is not permitted when the nominal thickness of the material exceeds 32 mm.
S7 - The maximum thickness of unheat–treated forgings shall not exceed 95 mm. The maximum thickness as–heat–treated may be 100 mm.
S8 - The maximum section thickness shall not exceed 75 mm for double–normalized–and–tempered forgings, or 125 mm for quenched–and–tempered forgings.
S9 - Both DN 200 and larger, and schedule 140 and heavier.
S10 - The maximum pipe size shall be DN 100 and the maximum thickness in any pipe size shall be Schedule 80.
S11 - Either DN 200 and larger and less than schedule 140 wall, or less than DN 200 and all wall thicknesses.

Time–dependent properties

T1 - Allowable stresses for temperatures of 370°C and above are values obtained from time–dependent properties.
T2 - Allowable stresses for temperatures of 400°C and above are values obtained from time–dependent properties.
T3 - Allowable stresses for temperatures of 455°C and above are values obtained from time–dependent properties.
T4 - Allowable stresses for temperatures of 480°C and above are values obtained from time–dependent properties.
T5 - Allowable stresses for temperatures of 510°C and above are values obtained from time–dependent properties.
T6 - Allowable stresses for temperatures of 540°C and above are values obtained from time–dependent properties.
T7 - Allowable stresses for temperatures of 565°C and above are values obtained from time–dependent properties.
T8 - Allowable stresses for temperatures of 595°C and above are values obtained from time–dependent properties.
T9 - Allowable stresses for temperatures of 620°C and above are values obtained from time–dependent properties.
T10 - Allowable stresses for temperatures of 425°C and above are values obtained from time–dependent properties.
T11 - Allowable stresses for temperatures of 350°C and above are values obtained from time–dependent properties.
T12 - Allowable stresses for temperatures of 650°C and above are values obtained from time–dependent properties.

Welding requirements

W1 - Not for welded construction.
W2 - Not for welded construction in Section III.
W3 - Welded.
W4 - Nonwelded, or welded if the tensile strength of the Section IX reduced section tension test is not less than 690 MPa.
W5 - Welded, with the tensile strength of the Section IX reduced tension test less than 690 MPa but not less than 655 MPa.
W6 - This material may be welded by the resistance technique.
W7 - In welded construction for temperatures above 450°C, the weld metal shall have a carbon content of greater than 0.05%.
W8 - Welding and oxygen or other thermal cutting processes are not permitted when carbon content exceeds 0.35% by heat analysis.
W9 - For Section I applications, for pressure retaining welds in 21/4Cr–1Mo materials, other than circumferential butt welds less than or equal to 89 mm in outside diameter, when the design metal temperatures exceed 450°C, the weld metal shall have a carbon content greater than 0.05%.
W10 - For Section III applications, material that conforms to Class 10, 13, 20, 23, 30, 33, 40, 43, 50, or 53 is not permitted for Class 2 and Class 3 construction when a weld efficiency factor of 1.00 is used in accordance with Note W12.
W11 - For Section VIII applications, Section IX, QW–250 Variables QW–404.12, QW–406.3, QW–407.2, and QW–409.1 shall also apply to this material. These variables shall be applied in accordance with the rules for welding of Part UF.
W12 - These S values do not include a longitudinal weld efficiency factor. For Section III applications, for materials welded without filler metal, ultrasonic examination, radiographic examination, or eddy current examination, in accordance with NC–2550, shall provide a longitudinal weld efficiency factor of 1.00. Materials welded with filler metal meeting the requirements of NC–2560 shall receive a longitudinal weld efficiency factor of 1.00. Other longitudinal weld efficiency factors shall be in accordance with the following:
(a) for single butt weld, with filler metal, 0.80
(b) for single or double butt weld, without filler metal, 0.85
(c) for double butt weld, with filler metal, 0.90
(d) for single or double butt weld, with radiography, 1.00
W13 - For Section I applications, electric resistance and autogenous welded tubing may be used with these stresses, provided the following additional restrictions and requirements are met:
(a) The tubing shall be used for boiler, waterwall, superheater, and economizer tubes that are enclosed within the setting.
(b) The maximum outside diameter shall be 89 mm.
(c) The weld seam of each tube shall be subjected to an angle beam ultrasonic inspection per SA–450.
(d) A complete volumetric inspection of the entire length of each tube shall be performed in accordance with SA–450.
(e) Material test reports shall be supplied.
W14 - These S values do not include a weld factor. For Section VIII, Division 1, and Section XII applications using welds made without filler metal, the tabulated tensile stress values shall be multiplied by 0.85. For welds made with filler metal, consult UW–12 for Section VIII, Division 1, or TW–130.4 for Section XII, as applicable.
W15 - The Nondestructive Electric Test requirements of SA–53 Type E pipe are required for all sizes. The pipe shall be additionally marked "NDE" and so noted on the material specification.

Type No.	Joint Description	Limitations	Joint Category	Extent of Radiographic or Ultrasonic Examination [Note (1), Note (2), Note(3)]
				(a) Full [Note (4)]	(b) Spot [Note (5)]	(c) None
(1)	Butt joints as attained by double‐welding or by other means that will obtain the same quality of deposited weld metal on the inside and outside weld surfaces to agree with the requirements of UW-35. Welds using metal backing strips that remain in place are excluded.	None	A, B, C, and D	1.00	0.85	0.70
(2)	Single‐welded butt joint with backing strip other than those included under (1)	(a) None except as in (b) below	A, B, C, and D	0.9	0.8	0.65
		(b) Circumferential butt joints with one plate offset; see UW-13(b)(4) and Figure UW-13.1, sketch (i)	A, B, and C	0.9	0.8	0.65
(3)	Single‐welded butt joint without use of backing strip	Circumferential butt joints only, not over 5/8 in. (16 mm) thick and not over 24 in. (600 mm) outside diameter	A, B, and C	NA	NA	0.6
(4)	Double full fillet lap joint	(a) Longitudinal joints not over 3/8 in. (10 mm) thick	A	NA	NA	0.55
		(b) Circumferential joints not over 5/8 in. (16 mm) thick	B and C [Note (6)]	NA	NA	0.55
(5)	Single full fillet lap joints with plug welds conforming to UW-17	(a) Circumferential joints [Note (7)] for attachment of heads not over 24 in. (600 mm) outside diameter to shells not over 1/2 in. (13 mm) thick	B	NA	NA	0.50
		(b) Circumferential joints for the attachment to shells of jackets not over 5/8 in. (16 mm) in nominal thickness where the distance from the center of the plug weld to the edge of the plate is not less than 11/2 times the diameter of the hole for the plug.	C	NA	NA	0.50
(6)	Single full fillet lap joints without plug welds	(a) For the attachment of heads convex to pressure to shells not over 5/8 in. (16 mm) required thickness, only with use of fillet weld on inside of shell; or	A and B	NA	NA	0.45
		(b) for attachment of heads having pressure on either side, to shells not over 24 in. (600 mm) inside diameter and not over 1/4 in. (6 mm) required thickness with fillet weld on outside of head flange only	A and B	NA	NA	0.45
(7)	Corner joints, full penetration, partial penetration, and/or fillet welded	As limited by Figure UW-13.2 and Figure UW-16.1	C and D [Note (8)]	NA	NA	NA
(8)	Angle joints	Design per U-2(g) for Category B and C joints	B, C and D	NA	NA	NA

General note: E = 1.00 for butt joints in compression.
Notes:
(1) Some welding processes require ultrasonic examination in addition to radiographic examination and other processes require ultrasonic examination in lieu of radiographic examination. See UW-11 for some additional requirements and limitations that may apply.
(2) Joint efficiency assignment rules of UW-12(d) and UW-12(e) shall be considered and may further reduce the joint efficiencies to be used in the required thickness calculetions.
(3) The rules of UW-12(f) may be used in lieu of the rules of this Table at the Manufacturer´s option.
(4) See UW-12(a) and UW-51.
(5) See UW-12(b) and UW-52.
(6) For Type No. 4 Category C joint, limitation not applicable for bolted flange connection.
(7) Joints attaching hemispherical heads to shell are excluded.
(8) There is no joint efficiency E in the design equations of this Division for Category C and D corner joints. When needed, a value of E not greater than 1.00 may be used.