CN108763686B - Method for checking strength of reinforced sealing flat cover - Google Patents

Method for checking strength of reinforced sealing flat cover Download PDF

Info

Publication number
CN108763686B
CN108763686B CN201810474054.XA CN201810474054A CN108763686B CN 108763686 B CN108763686 B CN 108763686B CN 201810474054 A CN201810474054 A CN 201810474054A CN 108763686 B CN108763686 B CN 108763686B
Authority
CN
China
Prior art keywords
flat cover
gasket
sealing
stress
stud
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN201810474054.XA
Other languages
Chinese (zh)
Other versions
CN108763686A (en
Inventor
邱砚明
牟力波
徐树林
支南
刘艳鹏
武君
车东光
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Harbin Electric Co ltd
Original Assignee
Harbin Electric Co ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Harbin Electric Co ltd filed Critical Harbin Electric Co ltd
Priority to CN201810474054.XA priority Critical patent/CN108763686B/en
Publication of CN108763686A publication Critical patent/CN108763686A/en
Application granted granted Critical
Publication of CN108763686B publication Critical patent/CN108763686B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/20—Design optimisation, verification or simulation
    • G06F30/23—Design optimisation, verification or simulation using finite element methods [FEM] or finite difference methods [FDM]
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16J—PISTONS; CYLINDERS; SEALINGS
    • F16J13/00—Covers or similar closure members for pressure vessels in general
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/10—Geometric CAD
    • G06F30/17—Mechanical parametric or variational design
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
    • G06F2119/06—Power analysis or power optimisation

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Geometry (AREA)
  • General Engineering & Computer Science (AREA)
  • Theoretical Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • Evolutionary Computation (AREA)
  • Mechanical Engineering (AREA)
  • Computational Mathematics (AREA)
  • Mathematical Analysis (AREA)
  • Mathematical Optimization (AREA)
  • Pure & Applied Mathematics (AREA)
  • Pressure Vessels And Lids Thereof (AREA)

Abstract

A strength checking method of a reinforced sealing flat cover belongs to the technical field of flat cover strength design of pressure containers. The invention aims to solve the problems that the strength checking method of a reinforced sealing flat cover is not available in the existing method, so that the design standard degree of the flat cover is poor, and the service life of a reinforced sealing bottle cover designed by a designer is short. The invention comprises the following steps: calculating the thickness of the flat cover without the reinforcement according to a flange design method specified by a pressure container design standard; step two: determining that the thickness of the reinforced flat cover is 0.55 times of the thickness of the non-reinforced flat cover; step three: and checking the structural strength of the dangerous section of the flat cover. The method for checking the strength of the reinforced sealing flat cover solves the problem that engineering designers design such parts, is feasible to be applied to actual design activities, and has obvious economic benefit along with the increase of the diameter of the outer ring of the flat cover.

Description

Method for checking strength of reinforced sealing flat cover
Technical Field
The invention relates to a strength checking method of a reinforced sealing flat cover, belonging to the technical field of flat cover strength design of pressure containers.
Background
The reinforced sealing flat cover has the advantages that the economic benefit is obvious, the flat cover connected by the flange and the stud belongs to a rigid body, the sealing failure is caused by transition deformation in the failure mode, the stress state of the flat plate is poor, the flat cover needs to be thick in order to meet the sealing requirement, so that more metal is consumed, and due to the fact that the ribs are added, the required thickness of the flat plate is reduced under the condition that the flat plate bears the same internal pressure, the metal consumption is reduced, and the economic benefit is obvious.
At present, a reinforced sealing flat cover structure is shown in an attached drawing 1 of the specification, a non-reinforced sealing flat cover structure is shown in an attached drawing 2 of the specification, for a reinforced flat cover, a strength design and check method of a flat cover for a non-sealing structure is given in a pressure container design standard (GB150), a thickness calculation formula of the reinforced flat cover in a connection form with a connecting piece of the reinforced flat cover is not given, meanwhile, a concrete case does not give an example of how to check the strength of the reinforced sealing flat cover, and the standard and calculation example support is lacked.
Disclosure of Invention
The invention aims to solve the technical problems and further provides a method for checking the strength of a reinforced sealing flat cover.
The technical scheme of the invention is as follows:
the known reinforced sealing flat cover structure has the following parameters: the thickness b of the flat cover after the rib design, the inner diameter Di of a flange connected with the flat cover, the calculated pressure is Pc, the designed temperature is t, the diameter of a sealing gasket acting force center circle is Dg, the outer diameter of a sealing gasket contact circle is D1, the inner diameter of the sealing gasket contact circle is D2, the diameter Da of a step dangerous section is achieved, and the diameter of a flat cover stud center circle is Db and the outer diameter of a flat cover ring is Dm.
The method for checking the strength of the reinforced sealing flat cover comprises the following steps:
the method comprises the following steps: calculating the thickness of the flat cover without the reinforcement according to a flange design method specified by a pressure container design standard;
step two: determining the thickness of the reinforced flat cover according to the design standard of the pressure container, and taking the thickness of the non-reinforced flat cover which is 0.55 times of the thickness of the reinforced flat cover;
step three: and checking the structural strength of the dangerous section of the flat cover.
The invention has the following beneficial effects:
1. the method for checking the strength of the reinforced sealing flat cover solves the problem that engineering designers design such parts, is feasible to be applied to actual design activities, and has obvious economic benefit along with the increase of the diameter of the outer ring of the flat cover.
2. The reinforced sealing flat has the defects that each flat cover needs to be designed and calculated due to non-standard components, great difficulty is brought to practical application, and the equipment is not supported by national standard components due to the fact that the large flat covers are adopted. If the diameter of the flat cover (more than DN500 is regarded as a large flat cover) is not very large, the economic benefit is not obvious even if a reinforced design is adopted. The economic advantage is only evident in the case of a relatively large nominal diameter of the flat lid. The design work of the flat cover can be carried out according to the method of the patent, and the safe service of the part in equipment can be ensured.
Drawings
FIG. 1 is a schematic view of a ribbed sealing flat cover structure;
FIG. 2 is a schematic view of a flat seal cover without ribs;
FIG. 3 is a schematic diagram of the structure size of a reinforced sealing flat cover;
FIG. 3a is a view from the direction A of FIG. 3;
FIG. 3b is an enlarged view taken at I in FIG. 3;
FIG. 3c is an enlarged view taken at II in FIG. 3;
FIG. 4 is a diagram of a simulation model for ANSYS finite element calculation of the stiffened flat cover;
FIG. 5 is a schematic diagram of a grid division of a reinforcement flat cover ANSYS finite element calculation;
FIG. 6 is a graph showing the loading of the reinforcement flat cover ANSYS finite element calculated pressure of 8 MPa;
FIG. 7 is a graph showing the loading of a reinforcement flat cover ANSYS finite element calculated pressure of 10 MPa;
FIG. 8 is a graph showing displacement at the seal face at a design pressure of 8 MPa;
FIG. 9 is a graph showing displacement at the sealing surface under a hydrostatic test pressure of 10 MPa;
FIG. 10 is a graph showing the stress of the dangerous cross-sectional path 1 of the flat cover at the design temperature and the calculated pressure of 8 MPa;
FIG. 11 is a graph showing the stress of the dangerous cross-sectional path 2 of the flat cover at the design temperature and the calculated pressure of 8 MPa;
FIG. 12 is a graph showing the stress of the dangerous cross-sectional path 3 of the flat cover at the design temperature and the calculated pressure of 8 MPa;
FIG. 13 is a graph showing the stress of the dangerous cross-sectional path 4 of the flat cover at the design temperature and the calculated pressure of 8MPa
FIG. 14 is a graph showing the stress of the dangerous cross-sectional path 5 of the flat cover at the design temperature and the calculated pressure of 8MPa
FIG. 15 is a graph showing the non-linear loading of the flat lid simulation model;
FIG. 16 is a graph of the deformation output of the flat-cap model for non-linear calculations (0.89405x20 ═ 17.9 MPa);
FIG. 17 is a graph showing the stress output of the flat cap model nonlinear calculation (0.89405x20 ═ 17.9 MPa);
FIG. 18 is a graph showing the output of the nonlinear calculation of the flat-cover model;
FIG. 19 is a graph showing the nonlinear internal pressure of 12.6MPa in the flat lid simulation model and the results of the deformation calculation;
Detailed Description
The first embodiment is as follows: the method for checking the strength of the reinforced sealing flat cover comprises the following steps:
the method comprises the following steps: calculating the thickness of the flat cover without the reinforcement according to a flange design method specified by a pressure container design standard;
step two: determining that the thickness of the reinforced flat cover is 0.55 times of the thickness of the non-reinforced flat cover;
step three: checking the structural strength of the dangerous section of the flat cover;
further, in the step one, according to a flange design method of a pressure vessel design standard specification, a specific method for calculating the thickness of the flat cover without the reinforcement is as follows:
1, calculating the width of the contact surface between the reinforcing rib flat cover and the pressure vessel mounting gasket
N＝(D1-D2)/2
Wherein N is the width of the pad contact surface, D1 is the outer diameter of the pad contact circle, and D2 is the inner diameter of the pad contact circle
2 finding the gasket basic seal width b0
b0＝N/2
3, calculating the effective sealing width b1 of the gasket according to the basic sealing width of the gasket:
Figure BDA0001663960210000031
4, calculating the diameter of a center circle of the action of the pressing force of the gasket:
Dg＝D1-2b1
wherein Dg is the diameter of the center circle on which the packing pressing force acts, D1 is the outer diameter of the packing contact circle, and b1 is the effective sealing width of the packing
5 calculating the minimum gasket pressing force Fa required in the pre-tightening state
Fa＝3.14Dg*b1*y
Fa is the minimum gasket packing force, b1 is the effective gasket seal width, and y is the specific gasket pressure
Minimum shim pressing force FP required under 6 operating conditions
FP＝2πDgb1mPc
Wherein Dg is the diameter of a central circle acted by the pressing force of the gasket, b is the effective sealing width of the gasket, m is the shape coefficient of the gasket, and Pc is the calculated pressure of the flat cover
7, obtaining a total axial force F caused by the internal pressure:
F＝0.25πDg2Pc
8 minimum bolt load required under pretension:
Wa＝Fa
9 minimum bolt area required under pretension
Figure BDA0001663960210000041
Minimum bolt load WP required under 10 operating conditions:
WP＝Fa+F
where Fa is the minimum gasket pressing force required in the pre-tightening state, F is the minimum bolt area Ap required in the total axial force 11 operating state due to the internal pressure:
Figure BDA0001663960210000042
12 total stud area required
Am＝max[Aa，Ap]
13 actual total area of stud
Figure BDA0001663960210000043
Design load of 14 screw
Figure BDA0001663960210000044
15 calculated load of stud
Figure BDA0001663960210000045
Moment arm of load bending moment of 16 flat-cover stud
Figure BDA0001663960210000046
17 flat cover calculation coefficient K
Figure BDA0001663960210000047
Calculated thickness of 18 flat covers
Figure BDA0001663960210000051
Further, in the third step, the specific method for checking the structural strength of the dangerous section of the flat cover comprises the following steps:
because the stress point of the reinforced sealing flat cover refers to the bending fulcrum nearest to the stud, the dangerous sectional area of the flat cover is the cross section a-a of the bending fulcrum
Firstly, according to the theory of material mechanics, the bending stress at the dangerous section aa of the flat cover and the shearing stress at the dangerous section aa of the flat cover are respectively obtained, and the formula is as follows:
Figure BDA0001663960210000052
in the formula, σamFor bending stress at aa of the dangerous section of the flat cover, W is the stud design load, DbIs the diameter of the central circle of the flat-covered stud DaIs the diameter of the dangerous section of the flat cover, and b is the thickness of the dangerous section of the flat cover
Figure BDA0001663960210000053
In the formula, τaThe shear stress at the aa position of the dangerous section of the flat cover is W, the design load of the stud is W, and the thickness at the aa position of the dangerous section of the flat cover is b;
according to the theory of mechanics of materials, under the conditions of bidirectional stress, tensile stress sigma and shear stress tau:
Figure BDA0001663960210000054
σ2＝0
Figure BDA0001663960210000055
in the formula, σ1Is the first principal stress, σ2Is the second principal stress, σ3Is the third principal stress, σ is the tensile stress, and τ is the shear stress
Using a fourth intensity theory:
Figure BDA0001663960210000061
then the following holds:
Figure BDA0001663960210000062
for components of the sealing type, GB150.3 gives a limiting value of 0.7[ sigma ]]tIn this patent, the values given are (0.7-1.0) [ sigma ]]tThe principle of selecting the coefficients is that the corner of the sealing surface is 0.7 when the sealing surface has a requirement on sealing, and 1.0 when the sealing performance has a non-strict requirement on the sealing surface, the following formula is established:
Figure 1
in the formula, σamBending stress at dangerous section of flat cover
When the above stress is pure shear stress:
Figure BDA0001663960210000064
σ2＝0
Figure BDA0001663960210000065
will be described above as σ1σ2σ3Substituting into the formula of the fourth intensity theory:
Figure BDA0001663960210000066
Figure BDA0001663960210000067
therefore, the fourth strength theory is to limit the value of the pure shear stress to not more than 0.6[ sigma ]]t(ii) a Namely: τ ≦ 0.6[ σ ]]t。
The second embodiment is as follows: according to the method for checking the strength of the reinforced sealing flat cover, the stress condition of the dangerous section of the structure needs to be solved by a numerical method, the requirement of structural limit analysis needs to be met, and the evaluation requirement of a stress classification method needs to be met in a local area (a sealing surface area); the reliability of the seal at the seal face is determined from the calculation result of the numerical method. The following is an example of practical engineering, and the schematic structural diagrams are shown in fig. 3, fig. 3a, fig. 3b and fig. 3c of the specification, which illustrate the principle of the patent:
in FIG. 3, a ribbed flat cover; secondly, a flange; ③ shell ring; fourthly, strip-shaped rib plates; o-shaped rubber ring; sixthly, an outer ring annular rib plate on the flat cover; seventh, inner ring rib plate on the flat cover
The flat cover is at the diameter phi 2656, which is also a dangerous section of the flat cover bearing bending moment and shearing stress, and is processed into the inclination of 1.5 degrees, and the flange connected with the flat cover through the stud is also processed into the inclination of 1.5 degrees. The design is that the micro deformation of the flange and the flat cover is more favorable for realizing sealing when the stud is pre-tightened.
1. Calculating conditions: designing and calculating the pressure Pc to be 8 MPa;
the design temperature t is 20 ℃;
16Mn steel forgings made of flange flat covers;
allowable stress of the material at normal temperature of the flange flat cover material { sigma } is 167MPa (according to GB150.2 table 9)
Allowable stress [ sigma ] of material at design temperature of flange flat cover material]t167MPa (according to GB150.2 Table 9);
modulus of elasticity E of flange material at design temperaturet201000MPa (according to GB150.2 Table B.14);
stud bolt: 35CrMoA, M64; a number of 64 pieces; the diameter of the stud root: 60.752 mm;
allowable stress [ sigma ] of stud material at normal temperature]b＝254MPa
The allowable stress of the stud material at the design temperature,
Figure BDA0001663960210000071
nut: 30 CrMoA; the stud center circle execution Db is 2974 mm;
the outer and inner diameters of the sealing surface of the flat cover are 2650 and 2600 in D1 and D2;
the outer diameter Dm of the flat cover ring is 3100 mm;
the thickness b of the flat cover is 200 mm;
the sealing gasket is an O-shaped rubber ring, and the Shore hardness is more than or equal to 75;
gasket specific pressure, y is 1.4 MPa;
the shape coefficient of the gasket, m is 1.0;
the diameter Dg of the central circle of the pressing force action of the gasket is obtained according to the GB150.3 rule; the design fastening force W of the stud is obtained according to the GB150.3 rule; the unexplained calculation symbols all take GB150.3 as the standard.
2. Calculating the thickness value [1] of the flange flat cover without the reinforcing ribs according to the method;
width of contact surface of gasket:
N＝(D1-D2)/2＝(2650-2600)/2＝25mm；
gasket basic seal width:
b0＝N/2＝25/2＝12.5mm；
a gasket effective seal width;
Figure BDA0001663960210000081
the diameter of the center circle of the pressing force of the gasket:
Dg＝D1-2b＝2650-2X8.94＝2632.1mm；
minimum shim clamping force required in the pre-tensioned state
Fa＝3.14Dgby＝πX2632.1X8.94X1.4＝103551.8N
Minimum gasket pressing force required under operating condition
FP＝2πDgbmPc＝2πX2632.1X8.94X1X8＝1183448.7N
Total axial force due to internal pressure:
F＝0.25πDg2Pc＝0.25πX2632.12X8＝43529933.5N
minimum bolt load required under pretension:
Wa＝Fa＝103551.8N
minimum bolt area required under pretension:
Figure BDA0001663960210000082
minimum bolt load required under operating conditions:
WP＝Fa+F＝1183448.7+43529933.5＝44713382.3N
total stud area required:
Am＝max[Aa，Ap]＝176036.9mm2
actual total area of the stud:
Figure BDA0001663960210000091
design load of stud
Figure BDA0001663960210000092
Calculated load of stud
Figure BDA0001663960210000093
Force arm of load bending moment of flat-cover stud
Figure BDA0001663960210000094
Flat cover calculation coefficient K
Figure BDA0001663960210000095
Flat cover thickness calculation (minimum thickness value required when no stiffener is provided)
Figure BDA0001663960210000096
3. Thickness delta of sealed flat cover of reinforced flangebIs determined
Thickness delta of sealed flat cover of reinforced flangebThe thickness delta of the reinforcing rib which is not provided is 0.55 times according to the practical design experienceP：
δb＝0.55δP＝0.55X364.4＝200.4mm
Thickness 200mm is taken to this patent.
4. Checking aa-face strength of dangerous section
4.1 determination of bending stress at aa section
Diameter at the critical section aa: da 2656mm
Moment arm La
La＝0.5(Db-Da)＝0.5X(2974-2656)＝159mm
Figure BDA0001663960210000101
4.2 determination of shear stress at aa section
Figure BDA0001663960210000102
Figure BDA0001663960210000103
4.3 aa Cross-section assessment
Evaluation of aa-surface strength of a dangerous section requires the following two equations:
Figure BDA0001663960210000104
τa≤0.6[σ]t
Figure BDA0001663960210000105
0.9[σ]t＝0.9X167＝150.3MPa
0.6[σ]t＝0.6X167＝100.2MPa
according to the fourth edition of mechanics of materials, the shear stress of the neutral plane reaches a maximum value which is 1.5 times of the average shear stress,
namely:
τa·max＝1.5τa＝1.5X27.5＝41.3MPa
139.6 is less than 150.3, 41.3 is less than 100.2, and the requirements are met.
The reinforcement flat cover value method is combined with the calculation result, a finite element method is used for carrying out load calculation on the structure, the stress value of the structure is obtained, the safety bearing capacity of the structure is authenticated by using a limit analysis method, and a stress classification method is used for carrying out safety evaluation; and the reliability of the sealing surface are obtained by using a calculation result of a numerical method, and the reliability of the sealing surface is determined by using deformation data obtained by calculation and analyzing the sealing characteristics of the sealing gasket selected according to the data so as to verify the correctness of the patent.
1. Input conditions
The structural dimension is according to the figure 3 of the specification, the related dimension is according to the data therein, the calculated pressure and the highest working pressure are both 8MPa, the test pressure is 10MPa, the design temperature is 20 ℃, the sealing gasket material is an O-shaped rubber ring, and the Shore hardness is more than or equal to 75.
2. The grid division, constraint and loading finite element method application program is ANSYS15.0, the calculation model is an integral entity model, the unit type is 20noad186, the stress pressure of gasket part loading is equal, and the simulation model is shown in figure 4 and figure 5. The model selects twenty-fourth of the whole material, and the calculated pressure is loaded below the flat cover (the other side of the reinforced flat cover). Since the sealing material coefficient m is 1, the same calculated pressure is applied to the gasket, which is also 8 MPa. The center of the stiffening flat cover is provided with a process hole with the diameter of 300, so that an equivalent surface pressure value-13.235 MPa is loaded on the D-plane ring of the figure 6, and the calculation formula is as follows:
Figure BDA0001663960210000111
pressure value of P-ansys model loading surface, MPa
Di-flat cover central opening inner diameter of 300mm
Inner diameter of Do-flat cover central reinforcing ring, 380mm
Pc-calculated internal pressure, MPa
The model ring applies symmetrical constraint to the surface, axial constraint is applied to the center line of the surface stud hole on the flat cover, and the loading and constraint of the simulation model are shown in figure 6
3. Analysis of calculation results
3.1, description
The numerical method is used for calculating, the corner displacement condition of the sealing surface is inspected under the working condition of 8MPa internal pressure, and whether the sealing of the O-shaped ring sealing ring meets the requirement of the working condition or not is judged; and whether the sealing structure of the flat cover and the O-shaped ring can still realize the sealing function under the working condition of the hydrostatic test is also examined. 3.2, the working condition of the sealing surface is analyzed under the working condition that the internal pressure is 8MPa, and the Y-direction displacement display graph of the structure ansys is shown in figure 8 under the working condition that the internal pressure is 8 MPa.
TABLE 1 internal pressure 8MPa sealing surface displacement data table
Value Note Unit Location X Location Y Location Z
1.1373 mm 1327.385729 -198.729475 0.000000
-0.26784 mm 1549.261201 -200.145140 0.000000
1.1414 mm 1282.026024 -198.857656 343.517838
-0.27303 mm 1496.236007 -200.224779 400.915230
According to the scheme, longitudinal displacement values at phi 2656 and the outer diameter phi 3100 of the flat cover ring are taken, and a group of data with large deformation is selected according to data of fig. 8 and table 1 to calculate the value of the rotation angle theta of the sealing surface.
Y1＝1.1414
Y2＝-0.2730
3
Dm-outermost ring diameter of flat cover, 3100mm
Da-Flat lid Point diameter, 2656mm
Figure BDA0001663960210000121
Through the above calculation, the seal surface rotation angle was 0.37 degrees. The sealing surface corner of the flange connected with the flat cover is not considered in the scheme, and the sealing can be realized as long as the sealing surface is not separated longitudinally because the O-shaped rubber ring is adopted in the scheme. The structure of the flat cover is considered to be satisfactory under working conditions. 3.3, analyzing the working condition of the sealing surface under the working condition of 10MPa of the hydrostatic test, and displaying the displacement display diagram in the Y direction of the calculation result of the structure ansys under the working condition of 10MPa of the hydrostatic test in a figure 9. The data are shown in Table 2.
Table 2 hydraulic test sealing surface displacement data table under 10MPa working condition
Value Note Unit Location X Location Y Location Z
1.4276 mm 1281.733551 -198.529285 343.439470
-0.34149 mm 1496.079379 -200.300096 400.873261
1.4216 mm 1327.200523 -198.562880 0.000000
-0.3349 mm 1549.090829 -200.264849 0.185564
According to the data in table 2, a group of data with large deformation is selected to calculate the value of the rotation angle theta of the sealing surface.
Y1＝1.4276
Y2＝-0.3419
Dm-outermost ring diameter of flat cover, 3100mm
Da-Flat lid Point diameter, 2656mm
Figure BDA0001663960210000131
The seal surface rotation angle was 0.46 degrees by the above calculation. The sealing surface corner of the flange connected with the flat cover is not considered in the scheme, because the sealing surface is the O-shaped rubber ring, the sealing can be realized as long as the sealing surface is not separated longitudinally, and the structure of the flat cover is considered to meet the working condition of a hydraulic test.
3.4 evaluation of Strength of Structure at design temperature under calculated pressure
TABLE 3 Flat cover stress evaluation path position description table
Serial number Path name Description of route location Remarks for note
1 1 Flat cover inner ring phi 300 section
2 2 Cross section at phi 540 position outside reinforcing ring in flat cover Singular point of departure stress
3 3 Dangerous cross section of flat coverPrevious point position Φ 2600
4 4 The dangerous section phi 2656 is carried by the flat cover
5 5 Bearing section phi 1580 of flat cover
Table 4 Flat lid stress evaluation results table (fourth intensity theory)
Figure BDA0001663960210000132
Figure BDA0001663960210000141
TABLE 5 summary of alphabetic meanings appearing in the data sheet
Figure BDA0001663960210000151
Figure BDA0001663960210000161
Data table 1
Figure BDA0001663960210000171
Data table 2
Figure BDA0001663960210000172
Figure BDA0001663960210000181
Data table 3
Figure BDA0001663960210000182
Figure BDA0001663960210000191
Data table 4
Figure BDA0001663960210000192
Data table 5
Figure BDA0001663960210000193
Figure BDA0001663960210000201
3.5 Flat lid simulation model nonlinear analysis
The limit analysis is applied to the structure, ANSYS software is applied, the limit bearing capacity of the structure is calculated by using a finite element method, and then the safety factor of the limit bearing capacity is 1.5 times. The yield limit is 1.5 times the safety factor.
The design pressure of the structure of the scheme is 8MPa, the calculated pressure also takes 8MPa according to the medium and the structure condition, and the final pressure of nonlinear analysis is determined to be 20 MP. The loading model is shown in FIG. 15.
The value of the internal pressure of the model loading is 20MPa, the value of the equivalent surface pressure at the central opening is 30.088MPa, and the calculation formula is as follows:
Figure BDA0001663960210000202
the non-linearity of the scheme is calculated to 17.9MPa as shown in figures 17 and 18, and then deformation out-of-tolerance overflows. The bearing limit value of the structure is 17.9 MPa. The time history is the result of no calculation of 1.0, since the deformation of the structure exceeds the value approved by the program, it indicates that the deformation overflow due to the out-of-tolerance when the structure is loaded to a pressure exceeding 17.9 MPa. That is to say, the maximum load of the structure is 17.9 MPa.
The structural deformation diagram when the patent operates to 12.6MPa is shown in the above figure 19, and the sealing surface corner data is shown in the following table.
TABLE 6 internal pressure 12.6MPa sealing surface corner data
Type Value Note Unit Location X Location Y Location Z
Result 3.8354 mm 1280.085475 -196.16335 342.99787
Result -1.1998 mm 1494.614764 -201.197047 400.46114
Result 3.8067 mm 1325.23967 -196.121386 0.000000
Result -1.1707 mm 1547.340017 -200.992756 0.000000
The loading internal pressure value of the model is 12.6MPa, and the rotation angle theta value of the sealing surface is calculated by taking the value calculation result. Y1-3.8354, Y2-1.1998, Dm-end outer ring diameter 3100mm Da-end point diameter 2656 mm.
According to the structure, the sealing surface of the flat cover is provided with a 1.5-degree bevel angle structure at phi 2656 in the figure 3, when the structure bears 12.6MPa of internal pressure, the edge corner deforms to 1.3 degrees, and the corner limit of the structure is not reached to 1.5 degrees, which shows that the flat cover structure can still realize sealing under the internal pressure of 12.6MPa, and the structure is safe. According to the provisions of clause 5.4.2.1 of JB4732-1995 (2005), if a given load does not exceed 2/3 of the structural plastic limit load, the relevant assessment of stress classification need not be satisfied at the structural specific site. The structure designed by the invention can be suitable for the working condition of the working pressure of 8MPa, and the sealing can also meet the sealing working condition according to the calculation of the sealing surface corner.
This embodiment is only illustrative of the patent and does not limit the scope of protection thereof, and those skilled in the art can make modifications to its part without departing from the spirit of the patent.

Claims (2)

1. The method for checking the strength of the reinforced sealing flat cover is characterized by comprising the following steps of:
the method comprises the following steps: according to a flange design method of a pressure container design standard specification, calculating the thickness of a flat cover without ribs, wherein the specific method comprises the following steps:
1) and (3) solving the width of the contact surface between the reinforcing rib flat cover and the pressure container mounting gasket:
N＝(D1-D2)/2
wherein N is the width of the pad contact surface, D1 is the outer diameter of the pad contact circle, and D2 is the inner diameter of the pad contact circle
2) Calculating the basic sealing width b of the gasket0：
b0＝N/2
3) And (3) calculating the effective sealing width b1 of the gasket according to the basic sealing width of the gasket:
Figure FDA0003451895030000011
4) and (3) calculating the diameter of a center circle of the action of the pressing force of the gasket:
Dg＝D1-2b1
wherein Dg is the diameter of a central circle for the pressing force action of the gasket, D1 is the outer diameter of a contact circle of the gasket, and b1 is the effective sealing width of the gasket;
5) and (3) solving the minimum gasket pressing force Fa required in the pre-tightening state:
Fa＝3.14Dg*b1*y
fa is the minimum gasket pressing force, b1 is the effective gasket sealing width, and y is the specific gasket pressure;
6) minimum gasket pressing force Fp required under operating conditions:
FP＝2πDgb1mPc
in the formula, Dg is the diameter of a central circle acted by the pressing force of the gasket, b1 is the effective sealing width of the gasket, m is the shape coefficient of the gasket, and Pc is the pressure-bearing calculated pressure of the flat cover;
7) the total axial force F due to the internal pressure was determined:
F＝0.25πDg2Pc
8) minimum bolt load required under pretension:
Wa＝Fa
9) minimum bolt area required under pretension:
Figure FDA0003451895030000021
10) minimum bolt load W required under operating conditionsP：
WP＝Fa+F
In the formula, Fa is the minimum gasket pressing force required in a pre-tightening state, and F is the total axial force caused by internal pressure;
11) minimum bolt area Ap required under operating conditions:
Figure FDA0003451895030000022
12) total stud area required:
Am＝max[Aa，Ap]
13) actual total area of stud:
Figure FDA0003451895030000023
14) design load of the stud:
Figure FDA0003451895030000024
15) calculated load of stud:
Figure FDA0003451895030000025
16) force arm of flat cover stud load bending moment:
Figure FDA0003451895030000026
17) flat cover calculation coefficient K:
Figure FDA0003451895030000027
18) calculating the thickness of the flat cover:
Figure FDA0003451895030000031
step two: according to the design standard of the pressure container, determining the thickness of the reinforced flat cover by using a flat cover calculation method, and taking 0.55 time of the thickness of the non-reinforced flat cover;
step three: and checking the structural strength of the dangerous section of the flat cover.
2. The method for checking the strength of the ribbed sealing flat cover according to claim 1, wherein: in the third step, the concrete method for checking the structural strength of the dangerous section of the flat cover comprises the following steps:
because the stress point of the reinforced sealing flat cover refers to the bending fulcrum closest to the stud, the dangerous sectional area of the flat cover is the cross section a-a of the bending fulcrum;
firstly, according to the theory of material mechanics, the bending stress at the dangerous section aa of the flat cover and the shearing stress at the dangerous section aa of the flat cover are respectively obtained, and the formula is as follows:
Figure FDA0003451895030000032
in the formula, σamFor bending stress at aa of the dangerous section of the flat cover, W is the stud design load, DbIs the diameter of the central circle of the flat-covered stud DaThe diameter of the dangerous section of the flat cover, and the thickness of the dangerous section of the flat cover;
Figure FDA0003451895030000033
in the formula, τaThe shear stress at the aa position of the dangerous section of the flat cover is W, the design load of the stud is W, and the thickness at the aa position of the dangerous section of the flat cover is b;
according to the theory of mechanics of materials, under the conditions of bidirectional stress, tensile stress sigma and shear stress tau:
Figure FDA0003451895030000034
σ2＝0
Figure FDA0003451895030000035
in the formula, σ1Is the first principal stress, σ2Is the second principal stress, σ3Is the third principal stress, σ is the tensile stressStress, τ is shear stress;
using a fourth intensity theory:
Figure FDA0003451895030000041
then the following holds:
Figure FDA0003451895030000042
for components of the sealing type, GB150.3 gives a limiting value of 0.7[ sigma ]]tThe principle of selecting the coefficients is that the corner of the sealing surface is 0.7 when the sealing surface has a requirement on sealing, and 1.0 when the sealing performance has a non-strict requirement on the sealing surface, the following formula is established:
Figure FDA0003451895030000043
in the formula, σamBending stress at the dangerous section of the flat cover;
when the above stress is pure shear stress:
Figure FDA0003451895030000044
σ2＝0
Figure FDA0003451895030000045
will be described above as σ1、σ2、σ3Substituting into the formula of the fourth intensity theory:
Figure FDA0003451895030000051
Figure FDA0003451895030000052
therefore, the fourth strength theory is to limit the value of the pure shear stress to not more than 0.6[ sigma ]]t(ii) a Namely: τ ≦ 0.6[ σ ]]t。
CN201810474054.XA 2018-05-17 2018-05-17 Method for checking strength of reinforced sealing flat cover Active CN108763686B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201810474054.XA CN108763686B (en) 2018-05-17 2018-05-17 Method for checking strength of reinforced sealing flat cover

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201810474054.XA CN108763686B (en) 2018-05-17 2018-05-17 Method for checking strength of reinforced sealing flat cover

Publications (2)

Publication Number Publication Date
CN108763686A CN108763686A (en) 2018-11-06
CN108763686B true CN108763686B (en) 2022-02-25

Family

ID=64008289

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201810474054.XA Active CN108763686B (en) 2018-05-17 2018-05-17 Method for checking strength of reinforced sealing flat cover

Country Status (1)

Country Link
CN (1) CN108763686B (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116680841B (en) * 2023-08-04 2023-10-13 中国特种设备检测研究院 Safety evaluation method and system for flat cover center open pore structure for pressure container

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA2065886C (en) * 1992-04-13 2002-06-18 Kevin E. Greenhead Closure cap with plastic liner
CN201666367U (en) * 2009-04-26 2010-12-08 茂名重力石化机械制造有限公司 High-pressure sealing cover structure without bending moment
CN204127563U (en) * 2014-10-29 2015-01-28 中国水利水电第五工程局有限公司 The dull and stereotyped end cap of seal of tube Dual side reinforced suppressed by PCCP pipeline
CN106951655A (en) * 2017-03-30 2017-07-14 中国航空工业集团公司西安飞机设计研究所 A kind of longitudinal reinforced flat plate general stability check method of axle pressure
CN107066704A (en) * 2017-03-23 2017-08-18 西安飞机工业（集团）有限责任公司 A kind of longitudinal reinforced flat plate general stability check method of axle pressure

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA2065886C (en) * 1992-04-13 2002-06-18 Kevin E. Greenhead Closure cap with plastic liner
CN201666367U (en) * 2009-04-26 2010-12-08 茂名重力石化机械制造有限公司 High-pressure sealing cover structure without bending moment
CN204127563U (en) * 2014-10-29 2015-01-28 中国水利水电第五工程局有限公司 The dull and stereotyped end cap of seal of tube Dual side reinforced suppressed by PCCP pipeline
CN107066704A (en) * 2017-03-23 2017-08-18 西安飞机工业（集团）有限责任公司 A kind of longitudinal reinforced flat plate general stability check method of axle pressure
CN106951655A (en) * 2017-03-30 2017-07-14 中国航空工业集团公司西安飞机设计研究所 A kind of longitudinal reinforced flat plate general stability check method of axle pressure

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
基于ANSYS Workbench的加筋平盖的有限元分析;吕凤娟 等;《信息技术》;20160620;第44卷(第3期);文章第1-4节，图1-7 *
螺栓连接加筋平盖的优化设计探讨;沈乐;《山东化学》;20170923;第46卷(第18期);全文 *
长圆形开孔平盖结构优化设计;高明 等;《化学工程与装备》;20170715(第7期);全文 *

Also Published As

Publication number Publication date
CN108763686A (en) 2018-11-06

Similar Documents

Publication Publication Date Title
CN103761365B (en) High-temperature pressure vessel creep fatigue strength design method based on service life
US10289772B2 (en) Method for creep-fatigue strength of plate-fin heat exchanger
CN108763686B (en) Method for checking strength of reinforced sealing flat cover
EP2891528A1 (en) Springback suppression component and method for manufacturing same
Diamantoudis et al. Design by analysis versus design by formula of high strength steel pressure vessels: a comparative study
Dimopoulos et al. Numerical methods for the design of cylindrical steel shells with unreinforced or reinforced cutouts
CN105069211A (en) Disc spring application method in high-temperature flange connection system
Chen et al. Numerical modelling of lockbolted lap connections for aluminium alloy plates
CN111143941B (en) Method for calculating axial compression bearing capacity of composite material reinforced wall plate
CN108871745B (en) Method for checking strength of non-taper-neck flange
CN108614945B (en) Design method of back pressure-bearing flat cover
Jelwan et al. Creep life design criterion and its applications to pressure vessel codes
Amiri et al. Nondestructive method to predict the buckling load in elastic spherical shells
CN109918747A (en) The calculation method of cross combination double angle component Compression Stability bearing capacity
Reddy et al. Parametric studies on wrinkling and fracture limits in deep drawing of cylindrical cup
Raviprakash et al. Effect of size and orientation of a centrally located dent on the ultimate strength of a thin square steel plate under axial compression
Lake et al. Design of bolted, flanged joints of pressure vessels
CN103674521A (en) Compensator verification method based on working condition separating design
Greiner Cylindrical shells under uniform external pressure
Taki Optimization of Flat Z-stiffened Panel Subjected to Compression
Burov et al. Numerical simulation of carrying capacity of the high-pressure metal composite vessel
Collier et al. Local Post Buckling: An Efficient Analysis Approach for Industry Use
CN114048607B (en) Method for analyzing limit bearing capacity of elastic boundary plate
Çağdaş The Influence Of Pressure Stıffness On The Torsıonal Bucklıng Of Lamınated Composıte Cylınders Under External Hydrostatıc Pressure
Phong Stress on the Nozzle of a Steel Vertical Storage Tank

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant