Pressure Vessel Engineering Ltd provides ASME Vessel

Pressure Vessel Engineering Ltd Provides Asme Vessel-Free PDF

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Sample flange the FEA model,Flange Model, 16 holes on 20 25 BCD 1 bolt size only 1 2 of one bolt will be used for the FEA model due. to symmetry,Loads on Flanges doc Page 2 of 16, Half of the 1 bolt is added A mirrored body creates a flanged pair. For FEA the bolt length is cut on the center of the gasket The gasket is removed and is replaced. by the loads it generates Split lines can be seen where the gasket loads HT and HG are applied. Loads on Flanges doc Page 3 of 16,Load HD Operating. HD is created by the pressure on the pipe attached to the flange Force Pressure x Area. HD P B 2 4, The load is generated on center line of the pipe but the ASME rules change the moment arm. depending on the attachment method When FEA is performed the load should be applied to the. attached pipe the FEA program will determine how the load is distributed. Loads on Flanges doc Page 4 of 16,Load HT Operating.
HT is created by the internal pressure acting on the gasket. 1 Pressure is applied to the exposed edge of the gasket. 2 The gasket tries to expand but is held in place by the flange faces. 3 The flange faces push back, The force between the gasket and the flange is shown as a triangle The force is zero at the OD. of the gasket there is no pressure at the gasket OD and thus no leakage At the inside edge the. pressure is the pressure in the pipe HT is the average pressure along the length mhT is. measured at the point 1 3 up the triangle the centroid of the force. The ASME rules reduce the width of the gasket This load is a design rule not a predictor of. actual flange stresses For FEA analysis the load HT is applied at the moment arm mhT away. from the bolt centerline,Loads on Flanges doc Page 5 of 16. Load HG Operating, HG operating is the force required to keep the flange sealed against the operating pressure It is. generated by tightening the bolts Load effective area x gasket factor m x Pressure If the. flange is self energizing does not need additional force to seal such as an o ring then HG. operating 0, Load HG operates through the center of the gasket but the gasket size is reduced by the ASME. rules to create an effective area Correlation to real gasket properties is difficult this load and. its moment arm is a design rule not a predictor of actual flange stresses. Loads on Flanges doc Page 6 of 16,Load HG Seating, HG seating is the force required to seat the gasket into the flange gasket face and be leak tight.
against a pressure of 0 psi HG operating provides the load required to keep the seal as the. operating pressure is increased, The force HG is loosely based on gasket physical properties but the gasket area used is modified. reduce from the actual gasket width because the code y factors are too high Correlation to real. gasket properties is impossible this load and its moment arm are a design rule not a predictor. of actual flange stresses, Force HG has an additional load added to it the gasket destroying or gasket crushing force. The computed seating load on the gasket is increased to the average of the required bolt strength. and the available bolt strength This code disaster greatly increases the required thickness of. flanges far beyond the loads that the gasket can handle. As a designer when the seating loads are too large and are caused by extra bolt area. several options are available, 1 make the bolts smaller in diameter or fewer in number Reducing the effective area of the. bolts reduces this theoretical gasket crushing force. 2 use weaker bolts same idea as above, 3 if material waste and cost are no object make the flange thicker This route often is used. when a custom appendix 2 flange must mate up to standard flanges such as B16 5 series which. seldom calculate to appendix 2 rules,Loads on Flanges doc Page 7 of 16.
ASME Loads Applied to the FEA Model,HG operating,HG seating. The flange model with the HD HG and HT loads applied. Combined operating and seating stresses case stresses Higher stresses can be seen at the pipe to. flange discontinuity Bending stresses can also be seen in the bolt Although the stresses look. high compared with the 20 000 psi membrane allowable stress for the flange and pipe the. stresses are minor if compared with a local discontinuity limit of 3x20 000 psi This flange. design although loaded to the maximum ASME allows can be considered to be lightly loaded. and wasteful of materials,Loads on Flanges doc Page 8 of 16. Operating loads only used for cycle life calculations seating HG is removed The gasket gets. seated once this is the load that the flange sees with each application and removal of pressure. The flange loads are extremely light for this flange that was designed around the gasket seating. Loads on Flanges doc Page 9 of 16,The Effective Seating Width of the Gasket. The effective seating width of the gasket removes the correlation between the physical. properties of the gasket material and the calculated gasket loads The seating width is typically. 1 2 the square root of the actual gasket width see table 2 5 2 for actual formulas which vary. depending on the gasket seating arrangement and the gasket width Traditionally this was done. to allow for rotation of the flanges under load which reduced the actual width of the gasket in. contact with the flange faces it was presumed that the inside edge of the gasket was not in. contact In reality the ASME rules including the flange rotation limits in 2 14 do not allow. enough flange rotation for the gasket to be partially in contact This effective width calculation. removes any possible correlation between ASME flange calculation methods and flange. manufacturers provided m and y values It was probably introduced because the table 2 5 1. gasket factors are too high, The seating and operating loads are design rules and should not be expected to predict. actual flange stresses They can be used in FEA analysis to simulate loads in a manner similar to. App 2 methods as required by U 2 g,Width b0 Width 2 0 5 sqrt b0 Effective Width.
0 000 0 000 0 000 0 000,0 125 0 063 0 125 0 063,0 250 0 125 0 177 0 125. 0 375 0 188 0 217 0 188,0 500 0 250 0 250 0 250,0 625 0 313 0 280 0 280. 0 750 0 375 0 306 0 306,0 875 0 438 0 331 0 331,1 000 0 500 0 354 0 354. 1 127 0 563 0 375 0 375,1 250 0 625 0 395 0 395,1 375 0 688 0 415 0 415. 1 500 0 750 0 433 0 433,1 625 0 813 0 451 0 451,1 750 0 875 0 468 0 468.
1 875 0 938 0 484 0 484,2 000 1 000 0 500 0 500, Effective width for a common gasket arrangement Table 2 5 2 sketches 1a and 1b. Loads on Flanges doc Page 10 of 16,Effective Gasket Width. b0 Width 2,1 000 0 5 sqrt b0,Effective Width,Effective Width. 0 000 0 200 0 400 0 600 0 800 1 000 1 200 1 400 1 600 1 800 2 000. Actual Width,Attachments,Attached are calculation sheets for. ASME code calculation for this flange This flange is limited by the seating case in. this case seating of a high strength spiral wound gasket m 3 y 10 000. FEA loads for the operating and seating case,FEA loads for the operating only case.
Loads on Flanges doc Page 11 of 16,1 Flanges ver 4 26 Page 1 of 3. 2 ASME VIII Div I Appendix 2,3 Code Flange Calculations Description. 4 Dimensions,5 Fig2 4 5 fd Select a flange design,6 22 000 A in flange OD. 7 16 000 Bn in ID uncorroded,8 1 750 t in flange thickness. 9 0 375 rf in hub corner radius,10 0 750 g0f in hub thickness r.
11 0 750 g1 in hub base thickness,13 17 750 GOD in gasket OD. 14 16 250 GID in gasket ID,15 3 00 m gasket factor. 16 10 000 gy gasket factor y,17 Bolting,18 20 250 varC in bolt circle dia. 19 1 000 BoltOD in bolt size,20 16 0 Nbolt number of bolts. 21 Operating Conditions,22 0 000 Corr in corrosion allowance.
23 100 0 P psi internal operating pressure,24 0 0 Pe psi external operating pressure. 25 Material Properties,26 NonCast CastMaterial Cast Or NonCast. 27 20 000 Sf psi allowable flange stress at DESIGN temp. 28 20 000 Sfa psi Allowable Flange Stress at ASSEMBLY temp. 29 27 900 000 Efo psi Operating Flange Modulus,30 27 900 000 Efs psi Seating Flange Modulus. 31 20 000 Sb psi allowable bolt stress at DESIGN temp. 32 20 000 Sba psi allowable bolt stress at ASSEMBLY temp. 33 Geometry Constraints,34 rMin max 1 4 g1 0 188 MAX 1 4 0 75 0 188 0 188. 35 NutG in PVELookup TEMATableD5 Lookup NutWidth BoltOD 1 796. 36 Rh in PVELookup TEMATableD5 Lookup Rh BoltOD 1 375. 37 E in PVELookup TEMATableD5 Lookup E BoltOD 1 063. 38 WrenchClearance varC 2 B 2 g0 Rh TEMA Table D 5 20 25 2 16 2 0 75 1 375 0 000. 39 CkWrenchClr WrenchClearance 0 0 0 Acceptable, 40 NutClearance varC 2 B 2 g0 rf NutG 2 TEMA Table D 5.
41 20 25 2 16 2 0 75 0 375 1 796 2 0 102,42 CkNutClr NutClearance 0 0 102 0 Acceptable. 43 EdgeClearance A E varC TEMA Table D 5 22 1 063 20 25 0 687. 44 ckEdge EdgeClearance 0 0 687 0 Acceptable,45 Calculated Dimensions. 46 g0 g0f Corr 0 75 0 0 750,47 gOne g1 Corr 0 75 0 0 750. 48 B Bn 2 Corr 16 2 0 16 000, 49 varR varC B 2 gOne Gasket width in contact 20 25 16 2 0 75 1 375. 50 varN GOD GID 2 Gasket width in contact 17 75 16 25 2 0 750. 51 b0 varN 2 Gasket seating width 0 75 2 0 375,Flanges ver 4 26 Page 2 of 3.
1 varb IF b0 0 25 Sqrt b0 2 b0 Effective seating width. 2 IF 0 375 0 25 SQRT 0 375 2 0 375 0 306,3 varG IF b0 0 25 GOD 2 varb GOD GID 2 GID. 4 IF 0 375 0 25 17 75 2 0 306 17 75 16 25 2 16 25 17 138. 5 hub rf Length of Hub 0 375 0 375,6 Bolt Loads VIII App 2 5. 7 Bolt size and class 1 8 UNC 2A, 8 H 0 785 varG 2 P end load 0 785 17 138 2 100 23 055. 9 He 0 785 varG 2 Pe end load external pressure 0 785 17 138 2 0 0. 10 HP 2 varb 3 14 varG m P contact load 2 0 306 3 14 17 138 3 100 9 886. 11 HD pi 4 B 2 P end load PI 4 16 2 100 20 106, 12 HDe pi 4 B 2 Pe end load external pressure PI 4 16 2 0 0. 13 HT H HD face load 23055 20106 2 949,14 HTe He HDe face load external 0 0 0.
15 Wm1 H HP bolt load 23055 9886 32 941, 16 Wm2 pi varb varG gy seating load PI 0 306 17 138 10000 164 849. 17 Am Max Wm1 Sb Wm2 Sba Bolt area required,18 MAX 32941 20000 164849 20000 8 242. 19 RootArea sq in PVELookup BoltSizing Lookup Root Area BoltOD 0 566. 20 Ab RootArea Nbolt 0 566 16 9 056,21 CheckExcess Ab Am 9 056 8 242 Acceptable. 22 Flange Loads App 2 5, 23 W lb Am Ab Sba 2 seating conditions 8 242 9 056 20000 2 172 984. 24 HG lb Wm1 H operating conditions 32941 23055 9 886. 25 TBoltLoad lb W Wm1 Nbolt 172984 32941 16 12 870. 26 Flange Moment Arms Table App 2 6 Integral flanges. 27 mhD in varR 0 5 gOne 1 375 0 5 0 75 1 750, 28 mhT in varR gOne mhG 2 1 375 0 75 1 556 2 1 841.
29 mhG in varC varG 2 20 25 17 138 2 1 556,30 Flange Moments App 2 6. 31 MD in lb HD mhD end pressure 20106 1 75 35 186,32 MT in lb HT mhT face pressure 2949 1 841 5 428. 33 MG in lb HG mhG gasket load 9886 1 556 15 384, 34 Mo1e in lb HDe mhD mhG HTe mhT mhG total operating external. 35 0 1 75 1 556 0 1 841 1 556 0,36 Mo1 in lb Max MD MT MG Mo1e total operating. 37 MAX 35186 5428 15384 0 55 998, 38 Mo2 in lb W varC varG 2 total seating 172984 20 25 17 138 2 269 196.
39 Graphs App 2 7 1 6 Values of F f T U V Y and Z,40 h0 sqrt B g0 SQRT 16 0 75 3 464. 41 hh0 hub h0 0 375 3 464 0 108,42 g1g0 gOne g0 0 75 0 75 1 000. 43 F PVELookup F FlangeFactor hh0 g1g0 0 909,44 V PVELookup V FlangeFactor hh0 g1g0 0 550. 45 smallF 1 1 1 000,46 K A B 22 16 1 375,47 T PVELookup T FlangeFactorK K 1 765. 48 U PVELookup U FlangeFactorK K 6 877,49 Y PVELookup Y FlangeFactorK K 6 258.
50 Z PVELookup Z FlangeFactorK K 3 246,51 d U V h0 g0 2 6 877 0 55 3 464 0 75 2 24 360. 52 e F h0 0 909 3 464 0 262, 53 L t e 1 T t 3 d 1 75 0 262 1 1 765 1 75 3 24 36 1 047. Flanges ver 4 26 Page 3 of 3,1 Flange Seating Stress App 2 7 8. 2 SHs smallF ABS Mo2 L gOne 2 B,3 1 ABS 269196 1 047 0 75 2 16 28 577. 4 CheckSHs SHs 1 5 Sfa 28577 1 5 20000 Acceptable,5 SRs 1 33 t e 1 ABS Mo2 L t 2 B.
6 1 33 1 75 0 262 1 ABS 269196 1 047 1 75 2 16 8 454. 7 CheckSRs SRs Sfa 8454 20000 Acceptable,8 STs Y ABS Mo2 t 2 B Z SRs. 9 6 258 ABS 269196 1 75 2 16 3 246 8454 6 943, 10 SAs SHs Max SRs STs 2 28577 MAX 8454 6943 2 18 515. 11 CheckSTs ABS STs Sfa ABS 6943 20000 Acceptable,12 CheckSAs SAs Sfa 18515 20000 Acceptable. 13 Flange Operating Stress App 2 7 8, 14 SHo smallF Mo1 L gOne 2 B 1 55998 1 047 0 75 2 16 5 945. 15 CheckSHo SHo 1 5 Sf 5945 1 5 20000 Acceptable,16 SRo 1 33 t e 1 Mo1 L t 2 B.
17 1 33 1 75 0 262 1 55998 1 047 1 75 2 16 1 759,18 CheckSRo SRo Sf 1759 20000 Acceptable. 19 STo Y Mo1 t 2 B Z SRo 6 258 55998 1 75 2 16 3 246 1759 1 444. 20 CheckSTo STo Sf 1444 20000 Acceptable, 21 SAo SHo Max SRo STo 2 5945 MAX 1759 1444 2 3 852. 22 CheckSAo SAo Sf 3852 20000 Acceptable,23 Flange Flexibility App 2 14. 24 Jseating 52 14 Mo2 V L Efs g0 2 h0 0 3, 25 52 14 269196 0 55 1 047 27900000 0 75 2 3 464 0 3 0 452. 26 CheckJSt ABS Jseating 1 ABS 0 452 1 Acceptable,27 Joperating 52 14 Mo1 V L Efo g0 2 h0 0 3.
28 52 14 55998 0 55 1 047 27900000 0 75 2 3 464 0 3 0 094. 29 CheckJOp ABS Joperating 1 ABS 0 094 1 Acceptable. 18 Flange Loads for FEA ver 1 12 ASME VIII div 1 App 2 Page 1 of 2. 20 Combined Loads Operating Seating Conditions Description. 22 Dimensions and Conditions,24 10 020 B ID uncorroded. 41 0 990 g1 hub thickness,42 0 000 Corr corrosion allowance. This flange design although loaded to the maximum ASME allows can be considered to be lightly loaded and wasteful of materials HD HG operating HG seating HT Loads on Flanges doc Page 9 of 16 Operating loads only used for cycle life calculations seating HG is removed The gasket gets seated once this is the load that the flange sees with each application and removal of pressure The

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