CCCR
GUIDANCE DOCUMENT
VESSELS AND DEVICES.
STANDARDS AND METHODS OF CALCULATION FOR STRENGTH AND TIGHTNESS OF FLANGE JOINTS
RD 26-15-88
Moscow 1990
GUIDANCE DOCUMENT
Date of introduction 01.07.89
This guidance document establishes standards and methods for calculating the strength and tightness of flanged connections of vessels and apparatus made of steel operating in the chemical, petrochemical and related industries under conditions of exposure to static and re-static loads. It is allowed to use this RD for calculating flange connections of pipelines and fittings, provided that clause 1.3 is met. The guidance document is applicable subject to the requirements of OST 26-291.
1. GENERAL REQUIREMENTS
1.1. The terms and symbols of the corresponding physical quantities are given in the mandatory Appendix 1. 1.2. Types of flange connections are shown in Fig. 1-4*. The application limits for flange connection types are given in Reference Appendix 5. *The drawing does not define the design. 1.3. The calculation formulas of this standard are applicable whenAND 
1.4. If the number of loading cycles caused by assembly and disassembly and changes in operating conditions (pressure, temperature) is more than 1000, then after checking the strength of the flanges according to Section 8, it is necessary to carry out a low-cycle strength calculation according to Section 9. 1.5. Operating temperature of elements flange connection determined on the basis of thermal calculations or test results. It is allowed to determine the design temperature of the flange connection elements according to table. 1 .
Table 1
|
Flange connection type |
Isolated |
Non-insulated |
||||
|
t f |
t To |
t b |
t f |
t To |
t b |
|
| Flat, butt welded (Fig. 1, 2) |
t |
0,95 t |
||||
| With loose rings (Fig. 3) |
t |
0,81 t |
||||
| Welded flanges for clamps (Fig. 4) |
t |
0,55 t |
||||
1.6. When the device operates under conditions of several design modes of temperature and pressure, calculations are made for conditions that ensure the strength and tightness of the flange connection in all modes.
2. PERMISSIBLE VOLTAGES
2.1. Allowable stresses for materials of bolts (studs) are determined by formulas provided: a) if the design temperature does not exceed 380°C for bolts (studs) made of carbon steels, low-alloy steels - 420°C, austenitic steels - 525°CB) if the calculated temperature of the bolts (studs) exceeds that specified in paragraph a
2.2. Safety factors P t, are given in table. 2.
table 2
|
Bolt material |
|||||
|
Working conditions |
Test conditions |
||||
|
tightening is not controlled |
tightening is controlled |
tightening is not controlled |
tightening is controlled |
||
|
Carbon steels |
|||||
|
Austenitic steels |
|||||
For testing and tightening conditions
B) for flanges according to fig. 1, 2, 3, 4, 11 in section S 0: for working conditions and tightening
For test conditions
B) for a ring loose flange: for working conditions and tightening
For test conditions
S 0.2 , s V, [s] 20 - are accepted according to GOST 14249 or other regulatory documentation at the design temperature. A flange connection design for test conditions is not required if the design pressure under test conditions is less than the design pressure under operating conditions multiplied by 1.35 . Notes: 1. For flanges according to drawing. 1 permissible stress in the section S 1, for operating conditions and tightening conditions when calculating taking into account the load from temperature deformations Q 1 can be increased up to 30%. 2. For flanges according to fig. 3 permissible stress for a free ring when calculating taking into account the load from temperature deformations Q 1 can be increased by 30%. (Changed edition, Amendment No. 1)
3. CALCULATION OF AUXILIARY QUANTITIES
3.1. Effective width of the gasket, mm:b 0 = b n at b n £ 15 mm
At b n > 15 mm
For oval or octagonal gaskets
3.2. Gasket characteristics m , q obhv, TO, E p are accepted according to the table. 4 . 3.3. Gasket compliance, mm/N.
.
For metal and asbestos metal gaskets
atn =0.
3.4. Compliance of bolts (studs) for flanges according to fig. 1 , 2 , 3 , 11 , mm/N
Where Lb = Lb 0 +0,28d - for the bolt, Lb = Lb 0 +0,56d - for hairpins, fb- accepted according to the table. 5. 3.5. Compliance of clamps for flanges according to fig. 4, mm/N
Where l h accepted according to OST 26-01-64. 3.6. Flange parameters* * In case of connection with flanges of different (materials or sizes) calculations should be made for each flange. 3.6.1. Equivalent bushing thickness, mm
Suh=K × S 0 ,
Where K- determined by the devil. 5. For flanges according to fig. 2, 3, 4
Suh = S 0 .
3.6.2. Odds
,
Where ; y 1 - determined by features. 6. For non-beaded spherical caps
.
3.6.3. Angular compliance of the flange, 1/N × mm
,
Where y 2 - determined by features. 7. For flange with spherical unflanged cover
3.7. Angular compliance of the free ring according to fig. 3.1/N × mm,
Where yTo- determined by the devil. 6. 3.8. Angular compliance of a flat cover, 1/N × mm,
Where 
;
3.9. Angular compliance of a flange loaded with an external bending moment, 1/N × mm, for flanges according to drawing. 12
;
For flange according to devil. 3
;
For free ring
;
3.10. Moment arms, mm: for flanges according to fig. 1, 2, 4 *
,
*For flanges according to fig. 4
;
For flanges according to fig. 3
,
,
,
4. RIGIDITY COEFFICIENT OF FLANGE CONNECTION
4.1. Flange connection stressed by internal or external pressure and external axial force: for connection according to drawing. 1, 2, 4
,
Where ; for connection according to fig. 4
For connections via crap. 3
For connection with cover
Where . 4.2. Flange connection loaded with external bending moment,
Where 
; for flanges according to fig. 3
.
5. CALCULATION OF LOADS
5.1. Resultant internal pressure, N,
**
**For conditions of vacuum or external pressure P< 0 5.2. Реакция прокладки в рабочих условиях, Н,
.
5.3. Load arising from temperature deformation, N*: *If a tube sheet or other part is clamped between the flanges, it is necessary to take into account the temperature deformation of this part. in connection according to the devil. 12
Where 
- thickness of the upper and lower flange in the connection according to drawing. 3
Where ; in connection according to the devil. 4
Where 
; - height of the upper lower stops in connection with the cover
,
Where 
;af ,
aTo ,
acr- determined according to OST 26-11-04-84; ah- determined according to Appendix 2. Notes.
1. When determining loads from temperature deformations, the design temperature of the flanges, covers, bolts (studs), tube sheet, free ring should be reduced by the temperature at which the flange connection is assembled (20°C). 2. If a tube sheet is clamped between the flanges or additional washers are installed to reduce the loads from thermal deformations, then when determining lb 0 it is necessary to take into account their thickness. (Changed edition, Amendment No. 1). 5.4. Bolt load P b in installation conditions, the greater of following values, Н*, * F<0, если усилие сжимающее. При определении Р б 4 . величина Q t учитывается только при Q t <0, при a <1в расчетах принимается a =1.
;
for flanges according to fig. 1, 2, 3;
For flanges according to fig. 4,
Where B 1 - accepted according to table. 5. For vacuum or external pressure conditions
R b =R b 2.
(Changed edition, Amendment No. 1). 5.5. Incremental load in bolts (studs) under operating conditions, N,
,
at a<1в расчетах принимается a=1.(Changed edition, Amendment No. 1).
6. CALCULATION OF BOLTS (STUDS)
6.1. Strength conditions for bolts (studs)*: *Value x >1 is allowed in agreement with one of the authors of the standard. for flanges according to fig. 1, 2, 3
;
**
**For vacuum and external pressure conditions where x =1.1+1.2; for flanges according to fig. 4
;
.
Note - when checking the strength of bolts for operating conditions, taking into account the load on the bolts due to tight thermal deformations, the permissible stress can be increased by 30%. (Changed edition, Amendment No. 1). 6.2. The recommended tightening torque value is given in Appendix 3 (recommended).
7. CALCULATION OF GASKETS
The gasket strength condition is checked for soft gaskets
.
8. CALCULATION OF FLANGES FOR STATIC STRENGTH*
8.1. Flange rotation angle when tightening
,
Where M 01 =Pb × b . *In case of connection with flanges of different sizes or materials, calculations should be made for each flange. 8.2. Increment of flange rotation angle under operating conditions
Where 
. 8.3. Meridional stress in the shell (bushing) on the outer and inner surfaces during tightening, MPa: for flanges according to fig. 1 in section S 1:
sn = s 1; s 12 =- s 1
Where 
,T- determined by the devil. 8, D *=
D
at D ³ S 1 ,D *=
D +
S 0 at D <S 1 and ¦ >1
,D *=
D +
S 1 at D <S 1 and ¦ =1
; for flanges according to fig. 1 in cross section S 0
s 21 = ¦ × s 1 ; s 22 =- ¦ × s 1 ,
Where ¦ - is determined by the devil. 9; for flanges according to fig. 2, 3, 4
s 21 =s 1 ; s 22 =-s 1 ,
Where 
. 8.4. Increments of meridional stresses in the shell (bushing) on the outer and inner surfaces under operating conditions, MPa: for flanges according to fig. 1 in cross section S 1
D s 11 = D sn + D s 1 ; D s 12 = D sn + D s 1
,
;
In cross section S 0
D s 21 = D sn + ¦D s 1 ; D s 22 = D sn + ¦D s 1
;
D s 21 = D sn + D s 1 ; D s 2 2 = D sn + D s 1
8.5. Circumferential stresses in the shell (bushing) on the outer and inner surfaces during tightening, MPa: for flanges according to drawing. 1 in cross section S 1
For flanges according to fig. 1 in cross section S 0
D s 23 = 0.3¦× s 1 ; D s 24 = -0.3¦× s 1;
For flanges according to fig. 2, 3, 4
D s 23 = 0,3s 1 ; D s 24 = -0,3s 1;
8.6. Increments of circumferential stresses in the shell (bushing) on the outer and inner surfaces under operating conditions, MPa: for flanges according to fig. 1 in cross section S 1
,
;
In cross section S O
For flanges according to fig. 2, 3, 4
8.7. Condition for flange strength when calculating static strength: for flanges according to drawing. 1 in cross section S 1
when tightening
in working conditions
For flanges according to fig. 1, 2, 3, 4 in cross section S O
when tightening
;
in working conditions
9. CALCULATION FOR LOW-CYCLE FATIGUE
9.1. The calculated amplitude of the reduced conditional elastic stresses during tightening is determined by the formulaWhere the hell for flanges? 1 ab determined by features. 10. for flanges according to fig. 2
s 1 =0,
For flanges according to fig. 3, 4
s 1 =0,
9.2. The calculated amplitude of the reduced conditional elastic stresses under operating conditions is determined by the formula
For flanges according to fig. 1
Ds 1 = ab × Ds 11 ,
For flanges according to fig. 2
s 1 =0,
For flanges according to fig. 3, 4
s 1 =0,
9.3. The low-cycle strength of the flange connection is checked according to GOST 25859-83. To do this, using the stress amplitude determined from the tightening condition ( sa) according to clause 9.1, the permissible number of assemblies and disassemblies is determined [ N ]With. Based on the voltage amplitude determined for operating conditions () according to clause 9.2, the permissible number of cycles of changing the operating mode is determined [ N ]R. Strength condition for a given number of loads ( NWith , NR) will be executed if
10. CALCULATION OF FREE RING
10.1. Rotation angle of free ring
.
10.2. Hoop stress in a free ring, MPa
.
10.3. Strength condition
11. STIFFNESS REQUIREMENTS
Permissible angle of rotation for flanges according to drawing. 2, 3, 4:
for working conditions and tightening
For test conditions
For flanges according to fig. 1:
for working conditions and tightening
0.009 at D £ 2000 mm;
0.013 at D > 2000 mm;
for test conditions
0.011 at D £ 2000 mm;
0.015 at D > 2000 mm;
Table 3
|
Uncountable temperature, °C |
Allowable stress, MPa, for steel grades |
||||||
|
12Х18Н10Т, 10Х17Н13М2Т |
35Х, 40Х, 38ХА, 37Х12Н8Г8МФБ, 20ХН3А |
||||||
Continuation of the table. 3
|
Design temperature |
Allowable stress, MPa, for steel grades |
||||||
|
18Х12ВМБФР |
08Х15Н24В4ТР |
||||||
Table 4
|
Gasket type and material |
Coefficient m |
Specific gasket compression pressure q life safety fundamentals, MPa |
Allowable specific pressure [ q], MPa |
Compression ratio, K |
Conditional compression modulus E n× 10 -5, MPa |
| Flat made of: rubber according to GOST 7338 with hardness according to SHORE A up to 65 units |
0.3 × 10 -4 ´ |
||||
| rubber according to GOST 7338 with a SHORE A hardness of more than 65 units |
0.4 × 10 -4 ´ |
||||
| paronite according to GOST 481 with a thickness of no more than 2 mm | |||||
| asbestos cardboard according to GOST 2850 with a thickness of 1-3 mm | |||||
| fluoroplastic-4 TU 6-05-810 with a thickness of 1-3 mm | |||||
| aluminum grade AD according to GOST 21631 | |||||
| brass grade L63 according to GOST 2208 | |||||
| steel 05kp according to GOST 9045 | |||||
| Flat from: | |||||
| asbestos according to GOST 2850 | |||||
| in an aluminum shell, | |||||
| copper and brass | |||||
| steel 05KP | |||||
| steel type 12Х18Н10Т | |||||
| Ring with oval or octagonal cross-section from: | |||||
| steel 0.5KP according to GOST 9045 or 08Х13 according to GOST 5632 | |||||
| steel 08Х18Н10Т |
Table 5
|
Bolt diameter d, mm |
||||||||||
| Cross-sectional area of the bolt along the internal diameter of the thread* f b, mm 2 | ||||||||||
| Clamp load capacity IN n N | ||||||||||
| Stop height h 2 mm |
12. CALCULATION OF FLANGE CONNECTIONS WITH CONTACTING FLANGES
12.1. General requirements. 12.1.1. The terms and symbols of the corresponding physical quantities are given in the mandatory Appendix 1. 12.1.2. Types of flange connections are shown in Fig. 11. The limits of application of the specified types of flange connections are given in reference Appendix 5. 12.1.3. The limits of application of the calculation formulas of this section must comply with clause 1.3. 12.1.4. The design temperature of the flange connection elements is set in accordance with clause 1.5. 12.2. Permissible stresses. 12.2.1. The permissible stresses for the bolt material are determined according to clause 2.1 with an increase of 25%. 12.2.2. Allowable stresses for the flange material when calculating static strength are determined according to clause 2.5. 12.3. Calculation of auxiliary quantities. 12.3.1. The effective width and characteristics of the gasket are determined according to paragraphs. 3.1; 3.2. 12.3.2. Compliance of gasket contact belts, mm/N12.3.3. The design length and compliance of bolts (studs) are determined according to clause 3.4. 12.3.4. Flange parameters. 12.3.4.1. The angular compliance of the flange is determined according to clause 3.6. 12.3.5. The angular compliance of a flat cover is determined according to clause 3.8. The angular compliance of a spherical unflanged cover is determined according to clause 3.6.3. 12.3.6. Moment arms, mm:
;
;
.
12.3.7. Odds:
;
The drawing does not define the design
Approximate values h 1 , a 1 , a 2 are accepted according to table. 6:
;
;
;
;
Where 
For flanges according to fig. 11a
For flanges according to fig. 11b
Table 6
|
D |
|||
12.4.2. Loads in connection elements arising from temperature deformations
12.4.3. The bolt load under installation conditions is assumed to be the greater of the following values, N:
.
12.4.4. Incremental load in bolts (studs) under operating conditions, N
.
12.4.5. Reaction of gasket contact belts under operating conditions, N:
;
.
12.4.6. The maximum bending moment is assumed to be large, N × mm:
;
Where [ s ] 20 , [s] - accepted according to OST 26-11-04. 12.5. Calculation of bolts (studs) 12.5.1. The conditions for the strength of bolts (studs) and the amount of torque on the wrench are determined according to clause 6. 12.6. Gasket strength condition
.
12.7. Sealing condition
.
12.8. Flange calculation 12.8.1. Meridional stress in the shell (bushing), MPa
,
Where is the coefficient T determined by features. 8. 12.8.2. Circumferential stress in the shell (bushing), MPa
.
12.8.3. Shell strength condition
.
ANNEX 1
Mandatory
Terms and symbols
Table 7
|
Designation |
|
| Gasket width, mm |
b n |
| Clamp load capacity, N |
B 1 |
| Increase to compensate for corrosion, mm |
C |
| Flange internal diameter, mm | |
| Inner diameter of free ring, mm |
DTo |
| Flange outer diameter, mm |
Dn |
| Outer diameter of free ring, mm |
DNK |
| Diameter of the circle of bolts (studs), mm |
Db |
| Average gasket diameter, mm |
Djoint venture |
| Outer diameter of bolt (stud), m< |
d |
| The modulus of longitudinal elasticity of the material at a temperature of 20°C and calculated, MPa, is accepted according to GOST 14249: | |
| flange |
E 20 , E |
| bolts (studs) |
E 20 b, E b |
| free ring. |
E 20 To, E k |
| covers |
E 20 cr, E cr |
| Conditional compression modulus of gasket material, MPa | |
| External axial force (compressive with a minus sign), N |
F |
Cross-sectional area of the bolt (stud) along the internal diameter of the thread, mm 2 |
fb |
| Thickness of flange, free ring, mm |
h , hTo |
| Stop height, taken according to OST 26-01-64, mm |
h 1 |
| Height of the collar for supporting the clamp, mm |
h 2 |
| Thickness of the cover and flange part in the sealing area, mm |
hcr , scr |
| Gasket thickness, mm |
hP |
| Length of conical bushing, mm |
L |
| External bending moment, N × mm |
M |
| Radius of the sphere of a spherical unflanged cover, mm |
R c |
| The radius of the collar for supporting the clamp, taken according to OST 26-01-64, mm |
R |
| Design pressure, MPa | |
| Thickness of the tapered bushing at the junction with | |
| flange |
S 1 |
| shell, sleeve, bottom, mm |
S 0 |
| Thickness of shell, bottom, bushing, mm |
S 0 |
| Distance between the supporting surfaces of the nut and bolt head, stud, mm |
Lb 0 |
| Number of bolts (studs), pcs. |
n |
| Design temperature, °C | |
| flanges, covers |
tf |
| bolts (studs) | |
| free ring |
tTo |
| Temperature coefficient of linear expansion of the material, 1/°С | |
| flange |
af |
| bolts (studs) |
ab |
| free ring |
aTo |
| covers |
acr |
| Yield strength of bolts (studs) material at design temperature, MPa |
s T |
| Average value of the long-term strength for 10 5 hours at the design temperature, MPa |
s d × 10 5 |
| Average 1% creep limit for 10 5 hours at design temperature, MPa |
s 1% × 10 5 |
| Permissible stress of the material of bolts (studs) at a temperature of 20°C and design, MPa |
[s ] 20 b,[s ]b |
| Yield strength of flange material, MPa |
s 0,2 |
| Permissible stress of the flange material at a temperature of 20°C and design, MPa |
[s ] 20 , [s ] |
| Allowable stress of free ring material at design temperature, MPa |
[s ]To |
| Permissible stresses for flanges in sections S 1 and S 0 |
[s ]S 1 , [s ]S 0 |
| Design and permissible amplitude of conditional elastic stresses, MPa |
sA , [sA ] |
| Specified and permissible number of loading cycles |
N , [N ] |
APPENDIX 2
Linear expansion coefficients
Table 8
|
Steel grades |
Linear expansion coefficient a × 10 6, 1/°С depending on temperature, °С |
|||||
| 35 | ||||||
| 40 | ||||||
| 20Х13 | ||||||
| 14Х17Н2 | ||||||
| 35X 40X 38 HA | ||||||
| 20XH3A | ||||||
| 30XMA | ||||||
| 25Х1МФ | ||||||
| 25Х2М1Ф | ||||||
| 18Х12ВМБФР | ||||||
| 37Х12Н8Г8МФБ | ||||||
| 12Х18Н10Т 10Х17Н13М2Т | ||||||
| 45Х14Н14В2М | ||||||
| ХН35ВТ | ||||||
| 08Х15Н24В4 | ||||||
APPENDIX 3
Torque on the key when tightening
APPENDIX 4
Information
Example of flange connection calculation
Initial data: D= 400 mm, h= 300 mm, f= 200°С, E 20 = 1.99 × 10 5 MPa; Dn= 535 mm, hP= 2 mm, P= 0.6 MPa, E= 1.81 × 10 5 MPa; Db= 495 mm, S 0 = 8 mm, M= 0.83 × 10 7 N × mm, = 2.1 × 10 5 MPa; Djoint venture= 445 mm, d= 20 mm, F= 15000 N, E b= 2.01 d 10 5 MPa; bP= 12 mm, n = 20, With= 2 mm, af= 12.6 × 10 -6 1/°С; ab= 11.9 × 10 -6 1/°С Flange material - 20K steel. Bolt material - steel 35. Gasket material - PON paronite.
1. Calculation of auxiliary quantities
1.1. Effective spacer width
b o = b n= 12 mm.
1.2. The characteristics of the gasket are taken according to the table. 4: m = 2.5;qlife safety fundamentals= 20 MPa; TO = 0,9;En= 2 × 10 3 MPa. 1.3. Gasket Compliance
1.4. Bolt compliance
Where fb= 225 mm 2 is taken according to the table. 5. 1.5. Flange parameters 1.5.1. Equivalent bushing thickness
S o = S o = 8 mm.
1.5.2. Odds
1.5.3. Angular compliance of the flange
Where y 2 = 6.9 is determined by the line. 7. 1.6. The angular compliance of a flange loaded with an external bending moment is
1.7. Moment shoulders:
b = 0,5(D b -D sp) = 0.5(495 - 445) = 25 mm;
e = 0,5(Djoint venture - D - Suh) = 0.5(445 - 400 - 8) = 18.5 mm.
2. Flange connection stiffness coefficient
2.1. Flange connection loaded with internal pressure and external axial force:
2.2. Flange connection loaded with external bending moment:
=
;
3. Calculation of loads
3.1. Resultant internal pressure
Qd= 0.785 × D 2 joint venture × P= 0.785 × 445 2 × 0.6 = 93270.0 N.
3.2. Gasket reaction under operating conditions
Rn = p × Djoint venture × bO × m × P= 3.14 × 445 × 12 × 2.5 × 0.6 = 25151.4 N.
3.3. Load arising from temperature deformations
For installation conditions, the greater of the following values is accepted:
Pb1=0.5 × p × Djoint venture × buh × qlife safety fundamentals=0.5 × 3.14 × 445 × 12 × 20 = 167676.0 H
Pb1=0.4 × × P × fb=0.4 × 130 × 20 × 225 = 234000.0 H.
3.5. Incremental load in bolts under operating conditions
4. Bolt calculation
Where 
accepted according to the table. 3,
5. Calculation of gaskets
;
6. Flange calculation
6.1. Flange rotation angle when tightening:
6.2. Increment of flange rotation angle under operating conditions:
6.3. Meridional stresses in the shell on the outer and inner surfaces during tightening, MPa
Where T= 1.78 - accepted according to the devil. 8;
s 21 = 353.6 MPa; s 22 = -353.6 MPa.
6.4. Increments of meridional stresses in the shell on the outer and inner surfaces under operating conditions:
Ds 21 = Dsn +Ds 1 = 24.3 + 104 = 128.3 MPa;
Ds 22 = Dsn -Ds 1 = 24.3 + 104 = 128.3 MPa;
6.5. Circumferential stresses in the shell on the outer inner surfaces during tightening, MPa:
s 23 = 0.3 × s 1 = 0.3 × 353.6 = 106.1 MPa;
s 24 = -0.3 × s 1 = -0.3 × 356.6 = -106.1 MPa.
ss 0 = 425.6 MPa< 491 МПа.
The level of stress does not exceed the permissible level.
7. Stiffness requirement
q +Dq £ ,
0,0040 + 0,0012 = 0,0052<0,013.
APPENDIX 5
Application limits for flange connection types
Flat flanges (Fig. 2), with a free ring (Fig. 3), with clamps (Fig. 4) are recommended for use at ambient temperatures up to 300°C. Flanges with a smooth sealing surface are recommended for nominal medium pressures up to 1.6 MPa. Flanges with a protrusion-recess sealing surface are recommended for nominal medium pressures of more than 1.6 MPa. Flanges with a thorn-vaz sealing surface are recommended for gaskets that must be placed in a closed volume. Flanges with a sealing surface for a metal gasket of oval or octagonal cross-section are recommended for conditional medium pressures of more than 6.0 MPa. Contacting flanges (Fig. 11) are recommended for nominal pressures up to 0.6 MPa and vacuum with a residual pressure of at least 5 mm Hg. (0.005 MPa rest.) at temperatures up to plus 300°C.|
Flange connection parameters, mm |
Flange types |
|||
|
Butt-welded (Fig. 1) |
Flat (Fig. 2) |
Free (Fig. 3) |
Note |
|
| 1. Shell (bushing) thickness |
S = S 0 +1,3S, but not in all cases |
S 0 ³ S |
S- thickness of the shell to which the flange is welded; b accepted as hell 13 |
|
|
S 0 -S× 5 mm |
||||
|
S 1 = bS 0 |
||||
| 2. Length of tapered bushing t |
i= 1:3 bushing slope |
|||
| 3. Diameter of bolt circle |
Db ³ D + 2(S 1 + d + u) |
Db ³ D +2(2S 1 +d × u) |
Db >DTo +8(d+u 1) |
u= 6 mm u 1 = 8 mm |
|
Db |
Db = ε 1× D 0,931 |
ε 1 is accepted according to table. eleven d accepted according to the table. 13 |
||
| 4. Flange outer diameter Dn |
Dn ³ Db +A |
A accepted according to the table. 13 |
||
| 5. Gasket outer diameter D s |
D s = Db - e |
D s £ D s 1 |
e accepted according to the table. 13 |
|
| 6. Average gasket diameter Djoint venture |
Djoint venture = D s - b |
b accepted according to the table. 14 |
||
| 7. Number of bolts n |
t 1 is accepted according to table. 12 |
|||
| 8. Approximate flange thickness h |
l 1 is accepted according to the devil. 14 S 0 is accepted according to clause 3.6.1 |
|||
|
RU, MPa |
Diameters of bolts (studs) for devices, mm |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
Bolt diameter d b |
|||||||||||||
|
Bolt hole diameter d |
|||||||||||||
| For hex nuts | |||||||||||||
| For hex nuts with reduced wrench size | |||||||||||||
| For flat gaskets | |||||||||||||
| For oval or octagonal gaskets | |||||||||||||
Table 14
Gasket sizes
|
Gasket material |
Device diameter, mm |
Gasket width, mm |
| Flat non-metallic gaskets |
D£1000 |
|
|
1000 < D£2000 |
||
|
D > 2000 |
||
| Flat metal gaskets |
D£1000 |
|
|
D > 1000 |
||
| Flat Metal Sheathed Gaskets and Serrated Metal Gaskets |
D£1600 |
|
|
D > 1600 |
||
| Oval or octagonal gasket for RU³ 6.3 MPa |
D£600 |
|
|
600 < D£800 |
||
|
800 < D£1000 |
||
|
1000 < D£1600 |
Table continuation*
|
Gasket material |
Device diameter, mm |
Gasket width, mm |
Gasket thickness, mm |
| TRG "Graflek c) not reinforced with abturret |
400< D £ 600 |
||
|
£600D<1000 |
|||
|
£1000D<1500 |
|||
|
£400D<600 |
|||
| TRG "Graflek c) reinforced with abturret |
£400D<600 |
||
|
£600D<1000 |
Appendix 6
(Required)
STANDARDS AND METHODS OF CALCULATION FOR STRENGTH AND TIGHTNESS OF FLANGE JOINTS WITH GASKETS FROM THERMALLY EXPANDED GRAPHITE MATERIAL “GRAFLEX”
1. This appendix applies to the calculation of flange connections with tongue-and-groove sealing surfaces with gaskets from TRG "GRAFLEX".2. Characteristics of gaskets from TRG "GRAFLEX"* m, q obzh,.[q], are given in table. Modulus of elasticity of the gasket E p = 11,1q, where is the specific pressure on the gasket when tightening, MPa.3. Flange connection stiffness coefficient a determined in accordance with clause 4.1. Due to the fact that the modulus of elasticity of the gasket depends on the specific pressure on the gasket ( q), then when determining a The compliance of the gasket is determined by the method of successive approximations in the following way: The specific pressure on the gasket during tightening is preliminarily determined by the formula: R b- bolt force for installation conditions, determined according to clause 5.4. When determining R b- the coefficient in the first approximation is taken equal to unity. Then according to the formula E p = 11,1q The elastic modulus and compliance of the gasket are determined according to clause 3.3. If a If the result is greater than one, then it is necessary to determine the bolt force R b1, according to clause 5.4. with the resulting coefficient a and repeat the definition q And E. After this, determine the coefficient again a. *Note. The characteristics of the gaskets are presented by NPO "UNICHIMTEK" If, at a first approximation, the coefficient a turns out to be less than one, then when calculating flange connections the coefficient a is taken equal to unity and further approximations by definition a not required.|
Gasket type and material |
Coefficient m |
Specific gasket compression pressure qlife safety fundamentals, MPa |
Allowable specific pressure [ q], MPa |
| TRG gasket, unreinforced, with seal | |||
| TRG gasket reinforced without seal |
120 at t=2 mm*) 100 at t=3 mm*) |
||
| TRG gasket reinforced with seal | |||
| *) thickness of the gasket in a free state | |||
INFORMATION DATA
1. DEVELOPED BY NIIkhimmash, Ukrniikhimmash, VNIIneftemash EXECUTORS: Rachkov V.I., Ph.D.; Zusmanovskaya S.I., Ph.D.; Gaponova L.P.; Smolsky K.V., Ph.D.; Zavarov V.A.; Morozov V.G.; Pertsev L.P., Doctor of Technical Sciences; Golubova T.P.; Mamontov G.V., Ph.D.; Zeide I.E.; Wolfson B.S. 2. APPROVED AND ENTERED INTO EFFECT by the approval sheet of the Main Scientific and Technical Directorate dated November 29, 1988. 3. REPLACED OST 26-373-78, OST 26-01-396-78, OST 26-01-54-77. 4. REFERENCE REGULATIVE AND TECHNICAL DOCUMENTS
|
Number of clause, subclause, enumeration, appendix |
|
| GOST 481-80 | |
| GOST 2208-75 | |
| GOST 2850-80 | |
| GOST 5632-72 | |
| GOST 7338-77. | |
| GOST 9045-80 | |
| GOST 14249-80 |
Annex 1 |
| GOST 21631-76 | |
| GOST 25859-83 | |
| OST 26-01-64-83 |
Annex 1 |
| OST 26-11-04-84 |
2.5, 5.3, 12.4.6 |
| OST 26-291-87 |
Introductory part |
| TU6-05-810-76 |
|
1. General requirements. 1 2. Permissible stresses. 3 3. Calculation of auxiliary quantities. 4 4. Rigidity coefficient of the flange connection. 6 5. Calculation of loads. 7 6. Calculation of bolts (studs) 8 7. Calculation of gaskets. 9 8. Calculation of flanges for static strength*. 9 9. Calculation for low-cycle fatigue. eleven 10. Calculation of the free ring. 12 11. Requirements for rigidity. 12 12. Calculation of flange connections with contacting flanges. 16 Appendix 1 Terms and symbols. 20 Appendix 2 Linear expansion coefficients. 21 Appendix 3 Torque on the key when tightening. 21 Appendix 4 Example of calculation of a flange connection. 22 Appendix 5 Limits of application of types of flange connections. 26 Appendix 6 Standards and methods for calculating the strength and tightness of flange connections with gaskets made of thermally expanded graphite material “graflex”. 29 |
The assembly of flange connections must be carried out taking into account the following basic requirements. Bolts and studs of pipelines operating at temperatures above 300 C must be marked before installation. Gaskets must be sized to match the sealing surfaces of the flanges.
The assembly of flange connections must be carried out taking into account the following basic requirements. Bolts and studs of pipelines operating at temperatures above 300 C must be marked before installation. Gaskets must have dimensions corresponding to the sealing surfaces of the flanges.
Test plates for checking the sealing surfaces of flanges with a lip and a recess.| Tightening flange bolts. Assembling flange connections is one of the most frequently performed and critical operations during the repair and installation of valves. Only products whose roughness and flatness of the sealing surfaces of the flanges meet the established technical requirements are allowed for assembly. Transverse risks crossing the annular sealing surface of the gasket flange, nicks and other defects are not allowed.
The assembly of flange connections must be carried out without adjustment operations; The bolts must fit into the holes freely, without tension.
Assembling a flange connection consists of installing gaskets and securing the flanges using fasteners.
The assembly of flange connections begins with putting flanges on the ends of the pipes, then Simplex rubber rings are tightened and gaskets are installed between the ends of the pipes. Next, the flanges are brought together and tightened with bolts.
Assembling flange connections is one of the labor-intensive operations when installing air ducts, for the mechanization of which electric impact wrenches are used.
Mobile device for fitting flanges. Assembling flange connections consists of joining the flanges, installing gaskets and tightening bolts or studs. Before installation, bolts (studs) and pipeline gaskets operating at temperatures above 200 C must be marked.
Assembling flange connections is a critical operation in the manufacture of pipeline assemblies. To achieve good flange joint tightness and maintain it during operation, the flange joint must be properly assembled and tightened.
Assembling flange connections is one of the most common and critical operations in the manufacture and installation of pipelines, since their loss of seal during operation necessitates shutting down the pipeline. The passage of the product through leaks in flange connections occurs due to weak tightening of the flanges, distortions between the flange planes, insufficient cleaning of the sealing surfaces before installing the gasket, improper installation of the gasket, the use of gasket material that does not correspond to the parameters of the product, and defects on the sealing surfaces. The deviation from the perpendicularity of the flange to the pipe axis (distortion), measured along the outer diameter of the flange, should not exceed 0 2 mm for every 100 mm of the diameter of the pipeline intended to operate under pressure up to 1 6 MPa, 0 1 mm - under pressure 1 6 - 6 4 MPa and 0 05 mm - under pressure above 6 4 MPa. Thus, the displacement should not exceed 1 mm for a hole diameter of 12 - 18 mm, 1 5 mm for a diameter of 23 - 33 mm, 2 mm for a diameter of 40 - 52 mm. When installing flat welded flanges, the end of the pipe must be recessed into the flange.
Device KTB-1222 for pushing through flange mirrors. The assembly of flange connections is carried out using a square or using the device shown in Fig. VII-7. To join pipes for welding, use the devices shown in Fig. VII-8. An ordinary compass can be used to mark pipes at their installation site.
The assembly of flange connections on bolts or studs should be carried out freely, without the use of fitting operations.
Assembling flange connections of plastic pipelines involves installing gaskets between the flanges and tightening the bolts and nuts. If the ends of the pipes being connected do not coincide, adjustment work is performed, consisting of cutting a piece of pipe and welding (gluing) the bead sleeve or flanged pipe. Before welding the sleeve or pipe, a loose flange is placed on the cut end of the pipe. The exception is fluoroplastic and faolite pipelines, in which it is impossible to form a collar on the part under the conditions of the installation site. In this case, it is necessary to replace the entire part; this is done by installing straight pipe sections of the required length. If the ends of glass pipes do not match, correction can only be done by cutting off the excess piece of pipe. If the pipe is shorter than necessary, then the gap is eliminated with inserts no less than 200 mm long for connections on flanges with two tension rings and no less than 250 mm for connections on flanges with three tension rings.
The assembly of flange connections of pipeline elements is carried out on exposed, calibrated and reinforced supports, on which pipes, connecting parts or fittings are laid and pre-strengthened. A minimum gap is left between the ends of the joined pipeline elements, through which it is possible to insert the lens.
The assembly of flange connections of high-pressure pipelines is carried out in compliance with a number of additional requirements. Before assembly, the studs are rubbed with flake graphite or lubricated with graphite paste, composed of graphite thickly mixed with water in a ratio of 2: 1 or with glycerin. A graphite-copper lubricant of the following composition is also used: flake graphite-15 - 20%; copper powder-10 25%; glycerin - 60 - 70% Graphite-copper lubricant prevents the metal of the stud and nut from seizing at temperatures up to 600 C, ensuring the absence of scoring on the thread when tightening the connection.
The assembly of flange connections of high-pressure pipelines is carried out in compliance with a number of additional requirements. Before assembly, the studs are rubbed with flake graphite or lubricated with graphite paste, composed of graphite thickly mixed with water in a ratio of 2: 1 or with glycerin. A graphite-copper lubricant of the following composition is also used: flake graphite-15 - 20%; copper powder - 10 - 25%; glycerin - 60 - 70% Graphite-copper lubricant prevents the metal of the stud and nut from seizing at temperatures up to 600 C, ensuring the absence of nicks on the thread when tightening the connection.
Connecting pipes with plugs to glass pipelines. The assembly of flange connections is carried out in the following sequence. First, flanges are installed on the pipes, having a diameter 1 mm larger than the collar cone. Then a split rubber or plastic ring is placed on the collar, a rubber gasket is installed between the ends and the connection is assembled with bolts.
The assembly of flange connections on gaskets begins only after checking that the flanges are not distorted. To do this, first pre-assemble the connections without installing gaskets. The flanges must approach strictly parallel to the sealing surfaces. The non-parallelism of two flanges should not exceed twice the tolerance for deviation from the perpendicularity of the flange axes to the pipe axes. The gap size is checked with a feeler gauge at diametrically opposite points. You must strive to ensure that the gap around the entire circumference is the same and corresponds to the thickness of the gasket.
Permissible displacements of the edges of the circumferential seams of devices. The assembly of flange connections on bolts or studs must be carried out freely without adjustment operations. Flange connections must be tightened simultaneously using diametrically opposed bolts or studs. The final tightening of flange connections assembled using mastics should be performed after they are completely assembled, with a break necessary for the mastic to dry. Tightening of flange connections with gaskets made of corded asbestos and a thick layer of mastic is done in a hot state, heating the entire apparatus with steam at 50 - 60 C.
It is recommended to assemble flange connections immediately with a full number of bolts or studs, so as not to return to the installation of this connection in the future. The nuts of the bolts in a flange connection should, if possible, be located on one side.
Dimensions of welded pipe joints. Assembly of flange connections begins only after checking that the flanges are not distorted. To do this, first pre-assemble the connections without installing gaskets. The flanges must approach strictly parallel to the sealing surfaces. The non-parallelism of two flanges should not exceed twice the permissible deviation from the perpendicularity of one flange to the pipe axis. The gap is checked with a feeler gauge at diametrically opposite points.
As a rule, the assembly of flange connections is carried out at positive temperatures using torque wrenches with tightening force corresponding to the design. If the gasket is made of other materials, then the tightening force is selected experimentally to ensure strength and density.
The assembly of flange connections on gaskets is carried out only after checking that there is no distortion between the sealing surfaces of the flanges. To do this, pre-assemble the connections without gaskets. The flanges must approach strictly parallel to their sealing surfaces. The non-parallelism of the sealing surfaces of the mating flanges should not exceed the tolerances specified in table. V-11. If there is no distortion, final welding and assembly of the flange connection is performed.
The assembly of flange connections on gaskets begins only after checking that the flanges are not distorted. To do this, first pre-assemble the connections without installing gaskets.
The assembly of flange connections is carried out as follows: tightening is carried out gradually, alternately (with three tie rods) or alternating (crosswise - with four studs) tightening the nuts to avoid distortion of the connection. The studs are finally tightened with special wrenches with adjustable torque. The tightening forces of the studs must comply with the requirements of SNiP and the project.
The assembly of flange connections is carried out as follows: tightening is carried out gradually, alternately with three tie rods and alternating (crosswise) with four studs by tightening the nuts to avoid distortion of the connection. The studs are finally tightened with special wrenches with adjustable torque. The tightening forces of the studs must comply with the requirements of SNiP and the project.
Device for installing flanges on pipes. The process of assembling a flange connection consists of installing, aligning and fastening (attaching) the flanges at the ends of the pipes, installing the gasket and connecting the two flanges with coupling bolts. Before assembling the flange connection, the connected sections of pipes are verified for the straightness of their axes. The flanges are installed so that the bolt holes are symmetrically offset relative to the main axes of the fittings, apparatus and cross-section of the pipelines. Perpendicularity is checked using a flange square.
Device for assembling vertical sections of pipelines. When assembling flange connections on small-diameter pipelines, there is no need for fixtures and trolleys. The flanges are fitted using a square or in a jig.
When assembling a flange connection, the bolts are tightened gradually and evenly in such a way as to avoid distortions.
When assembling flange connections, the bolts must be tightened evenly by alternately screwing oppositely located nuts and ensuring that the flanges are parallel. The bolt nuts should be located on one side of the flange connection, and torque wrenches are recommended for tightening. The gaskets must have dimensions corresponding to the sealing surfaces of the collar bushings. The gasket material is specified by the project.
Self-aligning wedge gate valve. When assembling flange connections sealed with metal grooved gaskets, the following conditions must be observed.
When assembling flange connections, deviations from parallelism of the flanges are allowed for every 100 mm of nominal diameter; for pipelines of the 3rd category - 0 1 mm, 4th category - 0 2 mm. Correcting the distortion of flanges when connecting them by tightening bolts or studs, as well as eliminating the gap by installing wedge gaskets is not allowed.
When assembling a flange connection, it is necessary to strictly control the distance from the end of the pipe to the plane of the flange.
When assembling flange connections, the bolts are tightened one at a time, screwing oppositely located nuts with a torque wrench or torque wrench with a force specified by the design.
When assembling a flange connection, to prevent distortions, the bolts are tightened gradually by alternating tightening of the nuts with three bolts and alternating (crosswise) with four. The nuts are finally tightened with special wrenches with adjustable torque, while ensuring that the flanges and ends of the pipes are parallel.
When assembling flange connections, diametrically opposed nuts are tightened using a regular wrench. After tightening the studs with a normal length wrench, it is allowed to use wrenches with levers.
When assembling flange connections, the following requirements must be met: boring the internal diameter of the flange for the pipe Df ZOO mm is allowed according to the actual outer diameter of the pipe with a gap on the side of no more than 2 5 mm; the internal diameters of the butt weld flange and the pipes at the joint must match; if they do not match, a smooth transition must be made at an angle of no more than 10; When assembling flange connections, distortion is not allowed; gaskets and stud threads must be rubbed with silver flake graphite.
When assembling flange connections with pipes and parts, a symmetrical arrangement of holes for bolts and studs relative to the vertical axis must be ensured. The displacement of the holes of two adjacent flanges should not exceed half the difference in the nominal diameters of the holes and the bolt or stud being installed.
When assembling flange connections, ensure the correct location of the bolt holes; The bolt heads are placed on one side. Tightening bolts or studs is done in several steps in a criss-cross pattern.
The sequence of tightening the nuts of bolted connections is 1 - 8 - nuts. When assembling flange connections, the gap between the flanges should not exceed twice the tolerance for deviation from the perpendicularity of the flange axes to the axes of the pipe parts. The gap size is checked with a feeler gauge.
When assembling flange connections, ensure a symmetrical arrangement of holes for bolts and studs relative to the vertical axis.
When assembling flange connections using lenses, the latter must be inspected before installation and made sure there are no defects.
When assembling flange connections, the alignment of the bolt holes should only be checked using crowbars or mandrels.
When assembling flange connections, it is necessary to ensure a symmetrical arrangement of holes for bolts (studs) relative to the vertical axis, using splice wrenches.
When assembling flange connections, the nuts are screwed in using a normal wrench (without using a lever) and the studs are tightened in the diametrically opposite order.
When assembling flange connections, the correct location of the bolt holes should be observed; the bolt heads are located on one side. Tightening bolts or studs is done in several steps, crosswise.
When assembling flange connections, special attention must be paid to their reliable sealing.
When assembling a flange connection, first install several bottom bolts, after which a gasket is inserted into the gap, centering it while installing the remaining bolts.
When assembling flange connections, the use of bolts, studs and gaskets of the proper quality and size is of great importance.
Very often you can hear that “the gasket is leaking.” This statement is not always true. In fact, the connection is always leaking, and the gasket is only one of its components. The gasket is often expected to compensate for imperfections in flange surface finish and flange movement resulting from changes in operating temperature and pressure, vibration, etc. In many cases, gaskets can do this, but only if the correct type and material are selected and the correct installation procedure is followed.
A) What to do and what not to do when installing gaskets
- The main flange and counter flange must be the same type and correctly aligned. The total misalignment of the flanges should not exceed 0.4 mm.
- It is unacceptable to try to tighten flanges that are far apart from each other using fasteners. In such cases, it is necessary to use spacers using spacers on both sides of the spacer.
- Fasteners must be selected so that their elastic limit is not exceeded when the required load is applied.
- Additional tightening of bolts after a connection to a flat non-metallic gasket has been exposed to elevated temperatures is not permitted. (The gasket may harden and additional force will cause it to break.)
- It is necessary to ensure that there is no corrosion on the fasteners, as its presence will reduce the load-bearing capacity of the fasteners.
- You must ensure that the gasket material meets the specifications for the connection.
- It is necessary to make sure that there are no burrs or scratches on the working surfaces of the gasket, especially in the radial direction.
- The material should be selected so that the load capacity of the nuts is 20% higher than the load capacity of the studs or bolts. Always use washers of the same material as the nuts.
- If necessary, lubricant should be applied to the threads, but only in an even, thin layer. When using stainless steel fasteners, you should ensure that the specific type of lubricant can be used.
- Reuse of fasteners and gaskets is prohibited.
- Always use gaskets of the minimum permissible thickness.
- When cutting gaskets for flat flanges, the bolt holes must be cut before cutting the outer and inner diameter of the gasket. If the bolt holes are located close to the outer diameter of the gasket, cutting them out after cutting out the gasket can lead to disruption of its shape.
- Gaskets should be stored in a cool, dry place away from heat, moisture, oils and chemicals. They should also be stored flat and horizontal (i.e. not hung on hooks).
- Avoid applying grease to gaskets and flange faces.
B) Tightening the flange connection bolts.
Connections should be tightened evenly in three or even four passes, in a crisscross pattern, as shown in the figure. Please note that in this sequence, tightening one bolt may loosen the other(s), so it is recommended that all bolts be re-tightened in a circle as a final step. Some connections may need to be re-tightened immediately prior to commissioning to compensate for the relaxation of the gaskets and fasteners. Also, in some cases, when using certain types of gaskets in conjunction with flanges of certain types of connecting surface on heat exchangers, it is necessary to additionally tighten the connection during the initial heating of the heat exchanger.
B) Troubleshooting
| FAULT | POSSIBLE REASON | SOLUTION METHOD |
| The leak occurred immediately when the medium was supplied to the pipeline | Insufficient or excessive load in the connection or the load is applied unevenly | Carefully insert the new gasket. Check flange alignment, flange faces, and tighten bolts as described. |
| The leak occurred after a short period of use. |
|
|
| The leak occurred after several hours or days of use. | Chemical impact on the gasket from the environment or its mechanical destruction. | Check the chemical compatibility of the gasket material with the medium at a given concentration under operating conditions. Check the correct choice of gasket type. |
