LOGO HESSE AND RUSHTON METHOD

LOGO SHELL THICKNESS where t p = shell thickness (inch) P = Max allowable working pressure (psi) D = Inside diameter (inch) S = Max allowable tensile stress (psi) (Table 6-6) e = Efficiency of welded joint (Table 6-7) C = Corrosion allowance

LOGO SHELL THICKNESS Applicable if: 1. t p < 0.10D 2. t p > t min

LOGO Allowable Stress Estimation S = S u x F m x F s x F r x F a Where S u = Minimum Specified Tensile Strength F m = Material Factor F m = 1 for Grade A material F m = 0.97 for Grade B material F m = 0.92 for Grade C material F s = Temperature Factor (Use Table 6-7) F r = Stress Relief (SR) Factor F r = 1.06 When SR is applied F a = Radiographing Factor F a = 1.12 when Radiographing is applied and subsequent repair of defects

LOGO Minimum Specified Tensile Strength Specified ASMEMinimumAllowable Unit Tensile Stress, Thousands psi CodeTensileat Various Temperatures, °F Spec.Material DataStrength- 20 No.and DescriptionGrade1000 psito S-2Steel plates - flange andA firebox qualityB S-1Carbon steel for boilers Carbon-silicon steel,A S-42ordinary strength rangeB S-44Molybdenum steelA S-43Low-carbon nickel steelA S-55Carbon-silicon steel, high65 strength range, 4-1/2”A plates and under S-44B S-43B S-55B S-44C S-43C75 S-28Chrome-manganese- silicon A alloy steelB85

LOGO Temperature Factor Metal Temperature,Plate and Forged °FSteel, %Cast Steel, % Up to

LOGO Weld/Joint Efficiency EFFICIENCYCRITERIA LAP WELD (For circumferential Joint) Single Lap Single Lap with plug weld Double Lap BUTT WELD (For circumferential and longitudinal joints) Single Butt Single Butt with Back-up Strip Double Butt Double Butt with reinforce at center 55% 65% 70% 80% 90% t p < ⅝” t p > ⅝” t p < ⅝” t p < 1¼” t p > 1¼”

LOGO Stress Relief Factor Stress relieving is mandatory for: 1. t p > 1¼” 2. (For thinner plates) where D has a minimum value of 20 inches 3. ASTM A – ASTM A – 149 (under certain conditions)

LOGO Radiographing Factor Radiographing is mandatory for: 1. ASTM A – ASTM A – 149 (under certain conditions) 3. Lethal gases application 4. Nuclear Reactor applications

LOGO Sample Problem 1 A 12 in diameter S-2 Grade A steel has a working pressure and temperature of 500 psi and 300F respectively. Determine the type of weld to be used and plate thickness using Hesse and Rushton method. Assume zero corrosion allowance.

LOGO Sample Problem 2 Grade A S2 steel, butt welded pressured vessel for lethal gas application has an inside diameter of 20 inches. If the working pressure is 900 psi and the working temperature is 250ºF, what is the shell thickness of the vessel? (Use minimum corrosion allowance and Hesse and Rushton method).

LOGO HEAD Configurations  Torispherical  most common type of head used and usually the most economical to form  The I.C.R = I.D of the head or less between 90% to 95% of the I.D of the head  The I.K.R = 6% and 10% of the I.C.R of the head  The S.F = 10mm and 30mm

LOGO HEAD Configurations  2:1 Semi-Ellipsoidal  deeper and stronger than a torispherical head  more expensive to form than a torispherical head, but may allow a reduction in material thickness as the strength is greater  The I.C.R is 0.8 of the O.D of the head  The I.K.R is of the O.D of the head  The S.F =10mm and 30mm

LOGO HEAD Configurations  Hemispherical  allow more pressure than any other head  most expensive to form  The depth of the head is half of the diameter.

LOGO HEAD Configurations  Shallow Head  commonly used atmospheric tanks  not suitable for pressure vessels  I.C.R =1.5 to 2.0 times the I.D of the head  I.K.R = 32mm, 51mm or 76mm (depending on the diameter and customer requirements)  The S.F =10mm and 30mm

LOGO HEAD Configurations  Cones for Pressure Vessels  The maximum internal apex angle for cones =120 O  The I.K.R = 6% of the inside diameter of the vessel  The S.F =10mm and 30mm

LOGO HEAD Configurations  Flat.  A flat end with a knuckled outer edge  used as bases on vertical atmospheric tanks and lids for smaller tanks  The I.K.R =25mm, 32mm and 51mm  The S.F. = 10mm and 30mm

LOGO HEAD Configurations  Dish.  used for atmospheric tanks and vessels and for bulk heads or baffles inside horizontal tanks or tankers  Typically the I.C.R is equal to the diameter

LOGO HEAD THICKNESS Standard Ellipsoidal Hemispherical Standard Dished where L = crown radius in inches = D o – 6 K r = knuckle radius = 0.06 D o

LOGO HEAD THICKNESS Standard Dished  Values for W or dished heads Kr/LW

LOGO HEAD THICKNESS Standard Dished  Values for W or dished heads Kr/LW

LOGO HEAD THICKNESS Flat Heads *Lap Welded w/ or w/o Plug Welds: *Single or Double V Butt Welded *Cut from Solid PlateStandard Dished