1、 STP-PT-032 BUCKLING OF CYLINDRICAL, THIN WALL, TRAILER TRUCK TANKS AND ASME SECTION XII Prepared by: Guido G. Karcher, P.E. Consulting Engineer Little Egg Harbor, NJ, USA and Monte Ward, P.E. RTL, Inc. Gaviota, CA, USA Date of Issuance: September 1, 2009 This report was prepared as an account of wo
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9、NY 10016-5990 ISBN No. 978-0-7918-3270-7 Copyright 2009 by ASME Standards Technology, LLC All Rights Reserved Buckling of Cylindrical, Thin Wall, Trailer Truck Tanks STP-PT-032 TABLE OF CONTENTS Foreword v Abstract . vi 1 INTRODUCTION . 1 2 TEST PROGRAM . 2 3 TEST PROCEDURE AND RESULTS . 5 4 ANALYSI
10、S OF TEST RESULTS. 7 5 COMPARISON OF TANK TEST RESULTS AND CALCULATIONS . 9 6 COMPARISON OF TANK TEST RESULTS AND CODE COMPRESSIVE STRESS CRITERIA . 11 6.1 Method (5). 11 6.2 Method (6). 11 7 RECOMMENDATIONS FOR FUTURE WORK 14 8 CONCLUSIONS . 15 References 16 Acknowledgments 17 Nomenclature . 18 LIS
11、T OF TABLES Table 1 - Strain Gage Details . 4 Table 2 - Strain Gage Data and Tank Deflection Summary. 5 Table 3 - Tank Beam Bending Stress Comparison. 7 Table 4 - Calculated Loadings, Moments and Stresses at Test Intervals . 8 Table 5 - Measured and Calculated Tank Center Deflections 9 Table 6 - Str
12、ain Gage vs. Calculated Stress Comparison. 9 Table 7 - Summary of Allowable Buckling Stresses Using the Proposed Section XII Methods for Comparison with Tank Test Results. 13 Table 8 - Comparison of Test and Allowable Compressive Bending Stresses 13 LIST OF FIGURES Figure 1 - Overall View of Empty T
13、est Tank Prior to Testing. 2 Figure 2 - Test Tank Analytical Dimensions and Details 3 Figure 3 - Level Line and Deflection Reference Point. 3 Figure 4 - Strain Gages Bonded to the Top and Bottom of the Tank on Either Side of the Center Circumferential Weld Seam . 4 Figure 5 - Center Section Buckling
14、 of Tank 5 iii STP-PT-032 Buckling of Cylindrical, Thin Wall, Trailer Truck Tanks Figure 6 - Plot of all Strain Gage Data6 Figure 7 - Banding at Center Tank Weld10 Figure 8 - Bending Stress Distribution in a Typical Transport Tank and Critical Locations .14 iv Buckling of Cylindrical, Thin Wall, Tra
15、iler Truck Tanks STP-PT-032 FOREWORD This Standards Technology Publication is the result of a development project sponsored by ASME Pressure Technology Codes and Standards. The testing and analyses summarized in this report were performed to support the development of buckling design criteria and sh
16、ell stiffening details for both hazmat and non-hazmat transport tanks. Established in 1880, the American Society of Mechanical Engineers (ASME) is a professional not-for-profit organization with more than 127,000 members promoting the art, science and practice of mechanical and multidisciplinary eng
17、ineering and allied sciences. ASME develops codes and standards that enhance public safety, and provides lifelong learning and technical exchange opportunities benefiting the engineering and technology community. Visit www.asme.org for more information. The ASME Standards Technology, LLC (ASME ST-LL
18、C) is a not-for-profit Limited Liability Company, with ASME as the sole member, formed in 2004 to carry out work related to newly commercialized technology. The ASME ST-LLC mission includes meeting the needs of industry and government by providing new standards-related products and services, which a
19、dvance the application of emerging and newly commercialized science and technology and providing the research and technology development needed to establish and maintain the technical relevance of codes and standards. Visit www.stllc.asme.org for more information. v STP-PT-032 Buckling of Cylindrica
20、l, Thin Wall, Trailer Truck Tanks ABSTRACT Buckling of cylindrical pressure vessels under axial compression and bending is normally evaluated using the axial compression stress evaluation design methods in ASME Section VIII, Division 1. In 1998 the ASME Boiler and Pressure Vessel Code Committee appr
21、oved Code Case 2286, which introduced more comprehensive methods for determining allowable compressive stresses for cylinders, cones, spheres and formed heads due to external pressure, axial compression and bending. Section XII confirmed a need to develop similar such rules specific to the design of
22、 cylindrical, thin wall, trailer truck tanks. As first steps in the development of such rules, a full-scale tank buckling test was carried out, and the results of that were used to develop recommended design rules for consideration by Section XII. The results of this testing are summarized in this r
23、eport. In addition, Section XII design rule proposals have been outlined and are also summarized in this report. These proposals are based on the test results, past experience with transport tanks and the design methods of Code Case 2286-2, and are presented for consideration by Standards Committee
24、XII. vi Buckling of Cylindrical, Thin Wall, Trailer Truck Tanks STP-PT-032 1 INTRODUCTION New hazmat (hazardous material) and non-hazmat transport tanks will be constructed to the rules of the ASME Code Section XII 1. Long, thin wall, trailer truck tanks are used extensively for over-the-road transp
25、ort. These tanks typically operate with relatively low internal pressures from 25 to 45 psi (172 - 310 kPa) and are constructed with relatively stiff circumferential reinforcing rings at 60 in. (1500 mm) longitudinal spacing. These internal pressures cause positive circumferential stress in the tank
26、 wall. However, the longitudinal stresses addressed in this report are predominately bending and are not due to the internal pressures. Section XII confirmed a need to develop design rules similar to those in Code Case 2286-2 specific to the design for longitudinal bending in cylindrical, thin wall,
27、 trailer truck tanks. As first steps in the development of such rules, a full-scale tank buckling test was carried out, and the results of that were used to develop recommended design rules for consideration by Section XII. The results of that full-scale testing are summarized in this report. In add
28、ition, Section XII design rule proposals have been outlined and are also summarized in this report. These proposals are based on the test results, past experience with transport tanks and the design methods of Code Case 2286-2, and are presented for consideration by Standards Committee XII. 1 STP-PT
29、-032 Buckling of Cylindrical, Thin Wall, Trailer Truck Tanks 2 TEST PROGRAM A full-scale trailer truck tank was tested to evaluate the longitudinal bending loadings that would cause buckling. The tank was specially constructed for this testing by adding a 30 ft. (9144mm) long center section to a sta
30、ndard 40 ft. (12192mm) long cargo tank with the following details: Tank overall length: 70 ft. (21336mm) Tank shell OD: Do= 64 in. (1626mm) Tank shell thickness: t = 0.105 in. (2.7 mm) Material: SA 240, Type 304, SS Fya= 46 ksi (317 MPa), (actual yield strength from material test report). An overall
31、 photo of the empty test tank prior to testing is shown in Figure 1. 13Test Tank Driver Side5thwheelRear axle NPS 20 ManholeCenter pointFigure 1 - Overall View of Empty Test Tank Prior to Testing Figure 2 is a working sketch of the test tank showing the dimensions that were used for the calculations
32、 in this paper. As noted in Figure 1 and Figure 2, the rear axle and the 5th wheel support points were located and shimmed in a manner that minimized the tank end overhang which resulted in simply supported end conditions. This was done to maximize the center point bending moment and simplify the re
33、quired bending stress calculations. As noted, the tank was stiffened by U-shaped circumferential stiffeners made from 12 gage, 304 stainless steel continuously fillet welded to the tank OD (see Figure 2). The spacing of these stiffener rings was approximately 60 in. (1524 mm) on centers and the spac
34、ing at the critical center-span element, was measured to be 60 in. (1524 mm) on centers. 2 Buckling of Cylindrical, Thin Wall, Trailer Truck Tanks STP-PT-032 240” 360” Section 240” 60” 30” 17”793”840” 5thwheel Rear axle 1.63” 3.63” Ring Stiffeners Thk = 0.105” Center of span = Tank circumferential w
35、eld seams Notes: Drawing is not to scale Tank shell thickness, t = 0.105 in Tank OD = 64” Figure 2 - Test Tank Analytical Dimensions and Details As shown in Figure 3, a level line and reference point was mounted along the side of the tank to provide for approximate measurements of the center point d
36、eflections resulting from the water fill loadings. 12D e flection gag e Level lineFigure 3 - Level Line and Deflection Reference Point 3 STP-PT-032 Buckling of Cylindrical, Thin Wall, Trailer Truck Tanks Single element, uni-axial, resistance strain gages were bonded to the top and bottom of the tank
37、, 10 in. (254 mm) to the right and left of the center point circumferential weld as indicated in Figure 4. Table 1 is a summary of the strain gage details. 11Gage 2Gage 1Gage 4Gage 3Deflection reference60”Figure 4 - Strain Gages Bonded to the Top and Bottom of the Tank on Either Side of the Center C
38、ircumferential Weld Seam Table 1 - Strain Gage Details Micro-Measurements designations CEA-09-250UT-350 Resistance ohms 350 Gage Length (in.) 0.250 Gage Width (in.) 0.290 Gage Factor 2.086 Self Temperature Compensation No. 09 4 Buckling of Cylindrical, Thin Wall, Trailer Truck Tanks STP-PT-032 3 TES
39、T PROCEDURE AND RESULTS The tank outlet nozzle (NPS 3) was fitted with a hose connection, shut-off ball valve and a calibrated digital flow meter to monitor the volume of water pumped into the tank for the overload testing. Water was introduced into the tank through the inlet nozzle at a rate of app
40、roximately 140 gal/min (530 L/min). Water flow was stopped at the 3,000 gal (11,360 L), 6,000 gal (22,710 L) and 8,000 gal (30,280 L) levels to allow for the manual measurements of deflection and observations of the tank geometries. The tank buckled non-symmetrically as shown in Figure 5 at a flow m
41、eter reading of 8,094 gal (30,640 L) but 8,080 gal (30,590 L) is used in the calculations of this paper to account for the 14 gal (53 L) holdup in the hose between the meter and the tank fill nozzle. 158094 GallonsLevel lineFigure 5 - Center Section Buckling of Tank The strain gage data were recorde
42、d at 1 second intervals and saved in a computer file. The strain gage and deflection measurements at these inspection intervals are summarized in Table 2. Table 2 - Strain Gage Data and Tank Deflection Summary Time Sec Meter Gallons* Average Top Average bottom Average Fb= E Top psi Average Fb= E bot
43、tom psi Measured Deflection in. 190-227 start 0.0 1529 3000 -202 226 -5,700 6,400 0.4 2960 6000 -380 486 -10,750 13,750 0.8 3920 8000 -313 681 -8,600 19,300 1.2 4000 tank buckled 8094 Collapse * Fill rate 140 gal/min 5 STP-PT-032 Buckling of Cylindrical, Thin Wall, Trailer Truck Tanks All of the rec
44、orded strain gage data are shown in the chart in Figure 6. Cargo Tank Strain Gage Testing-1000-50005001000150020000 500 1000 1500 2000 2500 3000 3500 4000 4500 5000Time (sec)Strain(uin/inCH01 eCH02 eCH03 eCH04 eFigure 6 - Plot of all Strain Gage Data 6 Buckling of Cylindrical, Thin Wall, Trailer Tru
45、ck Tanks STP-PT-032 4 ANALYSIS OF TEST RESULTS As noted in Figure 2, there were short lengths of overhang (i.e., 30 in. (762 mm) at the 5th wheel and 17 in. (432 mm) at the rear axle supports) that tended to reduce the maximum bending moment at the center of the test tank. To evaluate the significan
46、ce of this, the bending moment at the center was calculated using the equations for a beam with end overhangs and for a beam without overhangs, both based on the dimensions shown in Figure 2. The results of this comparison are shown in Table 1. Table 3 - Tank Beam Bending Stress Comparison Calculate
47、d item With overhang Without overhang Mmax78,400w 78,606w Location of Mmax measured from the 5thwheel support point 397 in. 396.5 in. Where w = uniformly distributed load in lb/in. Based on this comparison, it was concluded that the test tank bending stresses could be determined by assuming the tank
48、 was a simply supported beam with a 5th wheel to rear axle support span of 793 in. (20,140 mm) and thus disregarding the effects of the relatively short overhangs. In addition to the evaluation of the beam end-point overhang, the tank dimensional changes due to the water weight were also considered.
49、 The hydrostatic head circumferential tension in the tank cylinder and the stresses due to the 1.2 in. parabolic sag (beam deflection) in the tank (see Table 2) for measure due to the water-fill loadings) add about 2 to 3% to the calculated bending stresses. Because of the relatively small magnitude of these stresses, they are not included in the results. This is a conservative assumption when evaluating the results of this testing. Therefore, the following equations (1) and (2
