SPREADSHEETS SERIES No. 0027SB

Wall Thickness Calculation of Cylindrical Shells Under Internal Pressure

ASME Section VIII Div 1 - UG 27 - Thickness of Shells Under Internal Pressure

(Enter values in yellow cells for calculations)

DATA INPUT

Design Conditions

Material

Design Pressure, Pd =

psig

Housing Material Specification ^{(1 to 7)}

Design Temperature, Td =

°F

Allowable Stress Shell, S =

psi

Long. joint efficiency (circ. stress), EL =

Dimensions

Circ. joint efficiency (long. stress), Ec =

Shell Inside Diameter, Di =

in.

See Table UW-12

Corrosion Allowance, CA =

in.

Nominal wall thickness, tn =

in.

Minimum required thickness, tr =

in.

Undertolerance Allowance ^(8)(9)(10), U1 =

default value = 0

Shell Outside Diameter, Do =

in.

Length, L =

in.

If tr ≤ tn acceptable

Notes:

(1)

S ≤ 66.66% of σy @ temp.

(2)

S > 66.66% but < 90% of σy @ temp.

(3)

(t ≤ 2¹/₂)

(4)

(2¹/₂ < t ≤ 4)

(5)

(4 < t ≤ 6)

(6)

Tensile strength of the Section IX reduced section tension test is not less than 100 ksi.

(7)

Tensile strength of the Section IX reduced tension test less than 100 ksi but not less than 95 ksi.

(8)

As per UG-16(c) Mill Undertolerance. Plate material shall be ordered not thinner than the design thickness. Vessels made of plate furnished with an undertolerance of not more than the smaller value of 0.01 in. (0.25 mm) or 6% of the ordered thickness may be used at the full design pressure for the thickness ordered. If the specification to which the plate is ordered allows a greater undertolerance, the ordered thickness of the materials shall be sufficiently greater than the design thickness so that the thickness of the material furnished is not more than the smaller of 0.01 in. (0.25 mm) or 6% under the design thickness.

(9)

As per UG-16(d) Pipe Undertolerance. If pipe or tube is ordered by its nominal wall thickness, the manufacturing undertolerance on wall thickness shall be taken into account except for nozzle wall reinforcement are a requirements in accordance with UG-37 and UG-40. The manufacturing undertolerances are given in the several pipe and tube specifications listed in the applicable Tables in Subsection C. After the minimum wall thickness is determined, it shall be increased by an amount sufficient to provide the manufacturing undertolerance allowed in the pipe or tube specification.

(10)

If you are ordering a head or other such fitting that is formed from plate, such as an elliptical, torispherical head, etc, you do not need to include the undertolerance. You do need to account for thinning during the forming of the head. Calculations should be done based on the minimum thickness after forming. The vendor of such heads should provide that information.

CALCULATIONS

Shell Design

Minimum required thickness [ASME UG-27 (c)]

Undertolerance thickness, U2 =

in.

U2 = t*U1

Nominal thickness adjusted for corrosion and undertolerance, nt =

in.

nt = t-CA-U2

Inside radius with corrosion & undertolerance removed, R =

in.

R = Di/2+CA+U2

Longitudinal Joint

Minimum required thickness, tL =

in.

t_L =

P R

S E - 0.6 P

Minimum required thickness, trL =

in.

t_r_L =

P R

+ CA

(11)

S E - 0.6 P

Circunferential Joint

Minimum required thickness, tc =

in.

t_c =

P R

2 S E + 0.4 P

Minimum required thickness, trc =

in.

t_rc =

P R

+ CA

(12)

2 S E + 0.4 P

Minimum required thickness [The greater between (11) and (12)], tr =

in.

Nominal wall thickness, tn =

in.

Check If tr ≤ tn

Maximum allowable working pressure [ASME UG-27 (c)]

Longitudinal Joint

Maximum allowable working pressure, MAWPL =

psig

MAWP_L =

S E nt

(13)

R + 0.6 nt

Circunferential Joint

Maximum allowable working pressure, MAWPc =

psig

MAWP_c =

2 S E nt

(14)

R - 0.4 nt

Max. allowable working pressure for the Body [The min. between (13) and (14)], MAWP =

psig

Check If MAWP ≥ P

Check Limitations

(1) Limitations: UG-27 and Appendix 1: ts < (R/2), P < 0.385 SE,

t_rL< (R/2)

If one isn’t met, review by Appendix 1-2.

PL < 0.385 SEL

(2) Limitations: UG-27 and Appendix 1: ts < (R/2), P < 1.25 SE,

t_rc< (R/2)

If one isn’t met, review by Appendix 1-2.

Pc < 1.25 SEc

Inside Volume =

ft³

V =

( (

π Di²

)

L ) / 1728

Weight =

lbs

W =

[ ( (

π (Do² - Di²)

)

L ) / 1728 ] ρm

RESULT

Design Conditions

Design Pressure, Pd =

psig

Design Temperature, Td =

°F

Material

Shell Material

Dimensions

Outside Diameter, Do =

in.

Nominal wall thickness, tn =

in.

Inside Diameter, Di =

in.

Length, L =

in.

Maximum allowable working pressure, MAWP =

psig

Inside Volume =

ft³

Weight =

lbs

Discussion and References

Information about Thickness of Shells Under Internal Pressure

ASME Section VIII Div 1 paragraph UG-27

Standards, Paragraph & Appendix

ASME BPVC.VIII.1 Rules for Construction of Pressure Vessels

ASME BPVC SEC II-D Material Properties

ASME Section VIII Div 1 paragraph UG-27 Thickness of Shells Under Internal Pressure

Cylindrical Shell

Minimum required thickness [ASME VIII.1 UG-27 (c)]

Longitudinal Joint

t =

P R

(1)

S E - 0.6 P

Circunferential Joint

t =

P R

(2)

2 S E + 0.4 P

Internal design pressure [ASME VIII.1 UG-27 (c)]

Longitudinal Joint

P =

S E t

(1)

R + 0.6 ts

Circunferential Joint

P =

2 S E t

(2)

R - 0.4 ts

Where:

P: Design Pressure, in bar (psig)

R: Inside Radius, in mm (inches)

S: Allowable Stress, in Mpa (psi)

E: Welding Efficiency

t: Minimum required thickness, in mm [The greater between (1) and (2)]

(1) Limitations: UG-27 and Appendix 1: t < (R/2), P < 0.385 SE, If one isn’t met, review by Appendix 1-2. Being R the inner radius.

(2) Limitations: UG-27 and Appendix 1: t < (R/2), P < 1.25 SE, If one isn’t met, review by Appendix 1-2. Being R the inner radius.