Very often you can hear that "the gasket is leaking." This statement is not always true. In fact, the connection always leaks, and the gasket is only one of its components. It is often expected that the gasket will be able to compensate for deficiencies in flange facing and flange movement due to changes in operating temperature and pressure, vibration, etc. In many cases, gaskets can do this, but only if they are of the right type and material, and the correct installation procedure is followed.

A) What to do and what not to do when installing gaskets

1. The main and counter flanges must be of the same type and properly aligned. The total misalignment of the flanges must not exceed 0.4 mm.
2. It is unacceptable to try to tighten flanges that are far apart with fasteners. In such cases it is necessary to use spacers using spacers on both sides of the spacer.
3. Fasteners must be selected in such a way that their elastic limit is not exceeded when applying the required load.
4. Additional tightening of the bolts after the connection with a flat non-metallic gasket has been exposed to elevated temperatures is not allowed. (The gasket may harden and additional force will cause it to break.)
5. Make sure that there is no corrosion on the fastener, as this will reduce the ability of the fastener to bear the load.
6. Ensure that the gasket material is within specification for the connection.
7. It is necessary to make sure that there are no nicks and scratches on the working surfaces of the gasket, especially in the radial direction.
8. The material should be chosen in such a way that permissible load on nuts was 20% higher than the allowable load on studs or bolts. Washers of the same material as the nuts should always be used.
9. If necessary, grease should be applied to the threads, but only in a uniform thin layer. When using stainless steel fasteners, make sure that the specific type of grease is acceptable.
10. Fasteners and gaskets must not be reused.
11. Gaskets of the minimum allowable thickness should always be used.
12. When cutting gaskets for flat flanges, the bolt holes must be cut before the outer and inner diameters of the gasket are cut. If the bolt holes are close to the outside diameter of the gasket, cutting them out after the gasket has been cut out may cause the gasket to deform.
13. Gaskets should be stored in a cool dry place away from sources of heat, moisture, oils and chemicals. They should also be stored flat and horizontal (i.e. not hung from hooks).
14. Avoid applying grease to gaskets and flange faces.

B) Tightening the bolts of the flange connection.

The joints should be tightened evenly in three or even four passes, in a criss-cross pattern, as shown in the figure. Keep in mind that in this sequence, tightening one of the bolts may cause the other(s) to loosen, so it is recommended that all bolts be re-tightened in a circle as a last operation. Some connections need to be retightened just prior to commissioning to compensate for the relaxation of gaskets and fasteners. Also, in some cases, when certain types of gaskets are used together with flanges of certain shapes of the connecting surface on heat exchangers, it is necessary to additionally tighten the connection during the initial heating of the heat exchanger.

C) Troubleshooting

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 be sized to match the flange faces.
Test plates for checking the sealing surfaces of flanges with raised and lowered flanges.| Tightening flange bolts. The assembly of flange connections is one of the most frequently performed and critical operations in the repair and installation of valves. Only products are allowed for assembly, in which the roughness and flatness of the sealing surfaces of the flanges comply with the established technical requirements. Transverse risks crossing the annular sealing surface of the flange for the gasket, nicks and other defects are not allowed.
The assembly of flange connections must be carried out without adjusting operations; the bolts must enter the holes freely, without tension.
Assembly flange connection consists of installing gaskets and fixing flanges with fasteners.
The assembly of flange connections begins with putting flanges on the ends of the pipes, then Simplex rubber rings are pulled on and gaskets are installed between the ends of the pipes. Next, the convergence of the flanges and their tightening with bolts begins.
The assembly of flange connections is one of the labor-intensive operations during the installation of air ducts, for the mechanization of which electric wrenches are used.
Mobile device for fitting flanges. The assembly of flange connections consists of joining flanges, installing gaskets and tightening bolts or studs. Before installation, bolts (studs) and pipeline gaskets operating at temperatures above 200 ° C must be prographic.
The assembly of flange connections is a critical operation in the manufacture of pipeline assemblies. In order to achieve a good tightness of the flange joints and maintain it during operation, the flange joint must be correctly assembled and tightened.
The assembly of flanged joints is one of the most common and critical operations in the manufacture and installation of pipelines, since their decompression during operation necessitates shutting down the pipeline. The product passes through leaks in flange connections due to weak tightening of the flanges, distortions between the planes of the flanges, insufficient cleaning of the sealing surfaces before installing the gasket, incorrect installation of the gasket, the use of gasket material that does not correspond to the parameters of the product, defects on the sealing surfaces. Deviation from perpendicularity of the flange to the axis of the pipe (skew), measured along the outer diameter of the flange, should not exceed 0 2 mm for every 100 mm of the diameter of the pipeline designed 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 with a hole diameter of 12 - 18 mm, 15 mm - with a diameter of 23 - 33 mm, 2 mm - with 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 flange mirrors. The assembly of flange connections is carried out using a square or using the fixture shown in fig. VII-7. For joining pipes for welding, 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 must be carried out freely, without the use of fitting operations.
The assembly of flange connections of plastic pipelines consists in installing gaskets between the flanges and tightening the bolts with nuts. If the ends of the pipes to be connected do not match, adjusting work is performed, consisting in cutting a piece of pipe and welding (gluing) a shoulder sleeve or a flanged pipe. Before welding the sleeve or branch pipe, a free flange is put on the cut end of the pipe. The exception is fluoroplastic and faolitic pipelines, in which it is impossible to form a shoulder 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 the glass pipes do not match, the correction can only be made by cutting off the excess piece of pipe. If the pipe is shorter than necessary, then the gap is eliminated by inserts with a length of at least 200 mm for connections on flanges with two tension rings and at least 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, fittings or fittings are laid and pre-reinforced. Between the ends of the joined elements of the pipeline, a minimum gap is left through which it is possible to insert a lens.
Assembly of flange connections of pipelines high pressure performed subject to a number of additional requirements. Before assembly, the studs are rubbed with flake graphite or lubricated with a graphite paste composed of graphite thickly mixed with water in a ratio of 2: 1 or with glycerin. Graphite-copper grease of the following composition is also used: flake graphite-15 - 20%; copper powder-10 25%; glycerin - 60 - 70% Graphite-copper lubricant excludes the setting of the metal of the stud and nut at temperatures up to 600 C, ensures the absence of burrs 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 a graphite paste composed of graphite thickly mixed with water in a ratio of 2: 1 or with glycerin. Graphite-copper grease of the following composition is also used: flake graphite-15 - 20%; copper powder-10 - 25%; glycerin - 60 - 70% Graphite-copper lubricant excludes the setting of the metal of the stud and nut at temperatures up to 600 C, ensures the absence of scratches on the thread when tightening the connection.
Connection of branch 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 shoulder, a rubber gasket is installed between the ends and the bolted connection is assembled.
The assembly of flange connections on gaskets begins only after checking that the flanges are not skewed. To do this, the connections are first pre-assembled without installing gaskets. Flanges must approach strictly parallel to the sealing surfaces. The non-parallelism of the two flanges should not exceed twice the tolerance for deviation from perpendicularity of the flange axes to the pipe axes. The gap is checked with a feeler gauge at diametrically opposite points. It is necessary to 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 welds of apparatuses. The assembly of flange connections on bolts or studs must be carried out freely without adjusting operations. Flange connections must be tightened simultaneously using diametrically opposite bolts or studs. The final tightening of flange joints assembled on mastics should be carried out after their complete assembly with a break necessary for the mastic to dry. The tightening of flange joints with gaskets made of corded asbestos and a thick layer of mastic is done in a hot state with heating of the entire apparatus with steam by 50 - 60 ° C.
Assembly of flange connections is recommended to be carried out immediately the full amount bolts or studs, so as not to return to the installation of this connection in the future. The nuts of the bolts in a flanged connection should, if possible, be on the same side.
Dimensions of welded pipe joints. The assembly of flange connections is started only after checking the absence of distortion of the flanges. To do this, the connections are first pre-assembled without installing gaskets. 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 axis of the pipe. The gap is checked with a feeler gauge at diametrically opposite points.
The assembly of flange connections, as a rule, is carried out at a positive temperature using torque wrenches with tightening tightening corresponding to the project. If the gasket is made of other materials, then the tightening force is selected empirically from the condition of ensuring strength and density.

The assembly of flange connections on gaskets is carried out only after checking for the absence of distortion between the sealing surfaces of the flanges. To do this, pre-assemble the connections without gaskets. Flanges must approach strictly parallel to their sealing surfaces. The non-parallelism of the sealing surfaces of the counter flanges should not exceed the tolerances specified in Table. V-11. In the absence of distortion, the final welding and assembly of the flange connection is carried out.
The assembly of flange connections on gaskets begins only after checking that the flanges are not skewed. To do this, the connections are first pre-assembled without installing gaskets.
The assembly of flange connections is carried out as follows: the tightening is carried out gradually, alternately (with three tie rods) or variable (crosswise - with four studs) tightening the nuts in order 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: the tightening is carried out gradually, alternately with three tie rods and alternating (crosswise) with four studs, tightening the nuts in order 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 mounting flanges on pipes. The process of assembling a flange connection consists of installing, aligning and fastening (lining) flanges at the ends of pipes, installing a gasket and connecting two flanges with tie bolts. Before assembling the flange connection, the pipe sections to be connected are verified for the straightness of their axes. The flanges are installed in such a way that the bolt holes are symmetrically displaced relative to the main axes of the fittings, devices and the cross section of pipelines. The perpendicularity is checked with a flanged square.
Device for assembling vertical sections of pipelines. When assembling flange connections on pipelines of small diameter, there is no need for fixtures and trolleys. Flanges are tapped on 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, tighten the bolts evenly by screwing oppositely located nuts alternately and keeping the flanges parallel. Bolt nuts should be located on one side of the flange connection, and torque wrenches are recommended for tightening. Gaskets must be sized to match the sealing surfaces of the collar bushings. The material of gaskets is indicated by the project.
Self-aligning wedge gate valve. When assembling flange connections sealed with corrugated metal gaskets, the following conditions must be observed.
When assembling flange connections, deviations from the 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 misalignment of the flanges when they are connected 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 pipe end to the flange plane.
When assembling flange connections, the bolts are tightened alternately, screwing oppositely located nuts with a calibrated or torque wrench with a force regulated by the project.

When assembling a flange connection, to prevent distortions, the bolts are tightened gradually by alternately tightening the nuts with three bolts and alternately (crosswise) with four. The nuts are finally tightened with special wrenches with adjustable torque, while monitoring the parallelism of the flanges and pipe ends.
When assembling flange connections, the tightening of diametrically opposite nuts is done with an ordinary wrench. After tightening the studs with a wrench of normal length, it is allowed to use wrenches with levers.
When assembling flange connections, the following requirements must be observed: boring of the inner 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 not more than 2 5 mm; the internal diameters of the butt-welded flange and the pipes at the junction must match; if they do not match, a smooth transition must be made at an angle of not more than 10; when assembling flange connections, distortion is not allowed, gaskets and threaded studs 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 offset of the holes of two adjacent flanges must not exceed half the difference between the nominal diameters of the holes and the bolt or stud being installed.
When assembling flange connections, the correct location of the bolt holes is observed; bolt heads are placed on one side. The tightening of bolts or studs is done in several steps crosswise.
The sequence of tightening the nuts of bolted connections 1 - 8 - nuts. When assembling flanged joints, 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 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, it is necessary to inspect the latter before installation and make sure that there are no defects.
When assembling flanged joints, the alignment of the bolt holes should only be checked using crowbars or mandrels.
When assembling flange connections, it is necessary to ensure the symmetrical arrangement of holes for bolts (studs) relative to the vertical axis, using colic wrenches.
When assembling flange connections, the nuts are screwed with a normal wrench (without using a lever) with the studs tightened in a 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. The tightening of bolts or studs is done in several steps, crosswise.
When assembling flange connections, it is necessary Special attention pay attention to their secure seal.
When assembling a flange connection, first install a few lower bolts, after which a gasket is inserted into the gap, centering it when installing the remaining bolts.

When assembling flange connections great importance has the use of bolts, studs and gaskets of proper quality and size.

CCCR

GUIDANCE DOCUMENT

VESSELS AND APPARATUS.
STANDARDS AND METHODS FOR CALCULATION OF STRENGTH AND TIGHTNESS OF FLANGED JOINTS

RD 26-15-88

Moscow 1990

GUIDANCE DOCUMENT

Introduction date 01.07.89

This guidance document establishes the standards and methods for calculating the strength and tightness of flanged joints of steel vessels and apparatuses operating in the chemical, petrochemical and related industries under the influence of static and repeated static loads. It is allowed to use this RD for the calculation of flanged connections of pipelines and fittings, provided that clause 1.3 is complied with. The guidance document is applicable subject to the requirements of OST 26-291.

1. GENERAL REQUIREMENTS

AND

1.4. If the number of loading cycles caused by assembly-disassembly and changes in the operating mode (pressure, temperature) is more than 1000, then after checking the strength of the flanges in section 8, it is necessary to calculate the low-cycle strength in accordance with section 9. 1.5. The operating temperature of the elements of the flange connection is determined on the basis of thermal calculations or test results. It is allowed to determine the design temperature of the elements of the flange connection according to Table. one .

Table 1

1.6. When the apparatus is operating under conditions of several design modes for temperature and pressure, the calculation is made for conditions that ensure the strength and tightness of the flange connection in all modes.

2. ALLOWABLE VOLTAGES

B) if the design temperature of the bolts (studs) exceeds that specified in paragraph a

2.2. Factors of safety P t are given in table. 2.

table 2

For test and tightening conditions

B) for flanges according to fig. 1, 2, 3, 4, 11 in section S 0: for operating conditions and tightening

For test conditions

B) for the ring loose flange: for operating conditions and tightening

For test conditions

S 0.2, s in, [ s ] 20 - are accepted in accordance with GOST 14249 or other regulatory documentation at design temperature. The design of a flange connection for test conditions is not required if the design pressure under test conditions is less than the design pressure under working conditions, multiplied by 1.35. Notes: 1. For flanges according to fig. 1 allowable stress in the section S 1 , for working conditions and tightening conditions when calculated taking into account the load from thermal deformations Q 1 can be increased up to 30%. 2. For flanges according to fig. 3 allowable stress for the free ring when calculated taking into account the load from temperature deformations Q 1 can be increased by 30%. (Changed edition, Rev. No. 1)

3. CALCULATION OF AUXILIARY VALUES

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 girth, TO, E p taken 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 hairpin, fb- taken 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 different (materials or sizes) flanges, the calculation should be made for each flange. 3.6.1. Equivalent bushing thickness, mm

Suh=K × S 0 ,

Where K- determined by hell. 5. For flanges according to fig. 2, 3, 4

Suh = S 0 .

3.6.2. Odds

,

Where ; y 1 - determined by hell. 6. For spherical caps without beading

.

3.6.3. Angular compliance of the flange, 1/N × mm

,

Where y 2 - determined by hell. 7. For flange with spherical non-flared cover

3.7. Angular compliance of the free ring according to fig. 3, 1/N×mm,

Where yto- determined by hell. 6.3.8. Angular compliance of the 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 fig. 12

;

For flange according to fig. 3

;

For free ring

;

3.10. Shoulders of moments, 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 THE FLANGED CONNECTION

,

Where ; for connection according to hell. 4

For connections by heck. 3

For connection with cover

Where . 4.2. Flange connection loaded with an external bending moment,

Where ; for flanges according to fig. 3

.

5. LOAD CALCULATION

**

**For vacuum conditions or external pressure P< 0 5.2. Реакция прокладки в рабочих условиях, Н,

.

5.3. Load arising from thermal deformations, N*: *If a tube sheet or other part is clamped between the flanges, it is necessary to take into account the thermal deformation of this part. in the connection according to hell. 12

Where - the thickness of the upper and lower flange in the connection according to fig. 3

Where ; in the connection according to hell. 4

Where ; - height of the upper lower stops in connection with the cover

,

Where ;af , ato , akr- 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 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 thicknesses. (Revised edition, Rev. No. 1). 5.4. Bolt load P b under installation conditions, the larger of the following values, H*, * 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 - taken according to the table. 5. For vacuum or external pressure conditions

R b =R b 2.

,

at a<1в расчетах принимается a=1.(Revised edition, Rev. No. 1).

6. CALCULATION OF BOLTS (STUDS)

;

**

**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 from the constraint of temperature deformations, the allowable stress can be increased by 30%. (Revised edition, Rev. No. 1). 6.2. See appendix 3 for recommended tightening torque (recommended).

7. CALCULATION OF GASKETS

.

8. CALCULATION OF FLANGES FOR STATIC STRENGTH*

,

Where M 01 =Pb × b . *In case of connection with different (by dimensions or materials) flanges, the calculation should be made for each flange. 8.2. Increasing the angle of rotation of the flange in working conditions

Where . 8.3. Meridional stress in the shell (sleeve) 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 hell. 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 section S 0

s 21 = ¦ × s 1 ; s 22 =- ¦ × s 1 ,

Where ¦ - is determined by hell. nine; 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 (sleeve) on the outer and inner surfaces under operating conditions, MPa: for flanges according to fig. 1 in section S 1

D s 11 = D sn + D s one ; D s 12 = D sn + D s 1

,

;

in section S 0

D s 21 = D sn + ¦D s one ; D s 22 = D sn + ¦D s 1

;

D s 21 = D sn + D s one ; D s 2 2 = D sn + D s 1

8.5. Circumferential stresses in the shell (sleeve) on the outer and inner surfaces during tightening, MPa: for flanges according to fig. 1 in section S 1

For flanges according to fig. 1 in section S 0

D s 23 = 0.3 ¦ × s one ; D s 24 = -0.3 ¦ × s 1;

For flanges according to fig. 2, 3, 4

D s 23 = 0,3s one ; D s 24 = -0,3s 1;

8.6. Increasing circumferential stresses in the shell (sleeve) on the outer and inner surfaces under operating conditions, MPa: for flanges according to fig. 1 in section S 1

,

;

in section S about

For flanges according to fig. 2, 3, 4

8.7. Flange strength condition when calculating static strength: for flanges according to fig. 1 in section S 1

when tightening

in working conditions

For flanges according to fig. 1, 2, 3, 4 in section S about

when tightening

;

in working conditions

9. CALCULATION FOR LOW-CYCLE FATIGUE

Where for flanges in hell. one ab determined by hell. 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. one

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. Checking the low-cycle strength of the flange connection is carried out in accordance with GOST 25859-83. For this, according to the stress amplitude determined from the tightening condition ( sa) according to clause 9.1, the allowable number of assemblies-dismantlings [ N ]from. According to the stress amplitude determined for operating conditions () according to clause 9.2, the permissible number of cycles of changing the operating mode is determined [ N ]R. The strength condition for a given number of loadings ( Nfrom , NR) will be executed if

10. CALCULATION OF A FREE RING

.

10.2. Ring stress in the free ring, MPa

.

10.3. Strength condition

11. RIGIDITY REQUIREMENTS

Permissible angle of rotation for flanges according to fig. 2, 3, 4:

for operating conditions and tightening

For test conditions

For flanges according to fig. one:

for operating 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

Continuation of the table. 3

Table 4

Table 5

12. CALCULATION OF FLANGED CONNECTIONS WITH CONTACT FLANGES

12.3.3. Estimated length and flexibility of bolts (studs) are determined according to clause 3.4. 12.3.4. Flange options. 12.3.4.1. The angular compliance of the flange is determined according to clause 3.6. 12.3.5. The angular compliance of the flat cover is determined according to clause 3.8. The angular compliance of the spherical non-beaded cover is determined according to clause 3.6.3. 12.3.6. Shoulder moments, mm:

;

;

.

12.3.7. Odds:

;

The drawing does not define the design

guide values h 1 , a 1 , a 2 are taken according to the table. 6:

;

;

;

;

Where For flanges according to fig. 11a

For flanges according to fig. 11b

Table 6

12.4.2. Loads in the connection elements arising from temperature deformations

12.4.3. The bolt load under mounting conditions is assumed to be the greater of the following values, N:

.

12.4.4. Load increment in bolts (studs) under operating conditions, N

.

12.4.5. The reaction of the contact belts of the gasket under working conditions, N:

;

.

12.4.6. The maximum bending moment is assumed to be large, N × mm:

;

Where [ s ] 20 , [s] - are 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 key 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 (sleeve), MPa

,

Where is the coefficient T determined by hell. 8.12.8.2. Circumferential stress in the shell (sleeve), MPa

.

12.8.3. Shell strength condition

.

ATTACHMENT 1

Mandatory

Terms and notation

Table 7

APPENDIX 2

Linear expansion coefficients

Table 8

APPENDIX 3

Torque on wrench when tightening

APPENDIX 4

Reference

Flange Connection Calculation Example

Initial data: D= 400 mm, h= 300 mm, f= 200°С, E 20 \u003d 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; Dcn= 445 mm, d= 20 mm, F= 15000 N, E b= 2.01 d 10 5 MPa; bP= 12 mm, n = 20, from= 2 mm, af= 12.6 × 10 -6 1/°С; ab\u003d 11.9 × 10 -6 1 / ° С Flange material - steel 20K. Bolt material - steel 35. Gasket material - PON paronite.

1. Calculation of auxiliary quantities

1.1. Effective pad width

b o= b n= 12 mm.

1.2. Characteristics of the gasket, 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\u003d 225 mm 2 is taken according to 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. Flange Angular Compliance

Where y 2 \u003d 6.9 is determined by hell. 7. 1.6. Angular compliance of a flange loaded with an external bending moment,

1.7. Shoulders of the moment:

b = 0,5(D b -D cn) = 0.5(495 - 445) = 25 mm;

e = 0,5(Dcn - D - Suh) = 0.5(445 - 400 - 8) = 18.5 mm.

2. Rigidity factor of the flange connection

2.1. Flanged 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 cn × P= 0.785 × 445 2 × 0.6 = 93270.0 N.

3.2. Gasket reaction under operating conditions

R n = p × Dcn × babout × m × P= 3.14 × 445 × 12 × 2.5 × 0.6 = 25151.4 N.

3.3. Load arising from temperature deformations

Under installation conditions, the greater of the following values ​​is taken:

Pb1=0.5× p × Dcn × buh × qlife safety fundamentals\u003d 0.5 × 3.14 × 445 × 12 × 20 \u003d 167676.0 H

Pb1=0.4 × × P × fb\u003d 0.4 × 130 × 20 × 225 \u003d 234000.0 H .

3.5. Load increment in bolts under operating conditions

4. Calculation of bolts

Where taken according to the table. 3,

5. Gasket calculation

;

6. Flange calculation

6.1. Flange rotation angle when tightening:

6.2. Increment of the angle of rotation of the flange in working conditions:

6.3. Meridional stresses in the shell on the outer and inner surfaces during tightening, MPa

Where T= 1.78 - taken according to hell. 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 stress state level does not exceed the allowable one.

7. Stiffness requirement

q +Dq £ ,

0,0040 + 0,0012 = 0,0052<0,013.

APPENDIX 5

Limits of application of types of flange connections

2 - for flanges according to fig. one

Table 11

Dimensionless parameter ε 1 depending on RU

Table 13

Auxiliary quantities d , a And e for bolts (studs)

Table 14

Gasket sizes

Table continuation*

Appendix 6

(required)

STANDARDS AND METHODS FOR CALCULATION OF THE STRENGTH AND TIGHTNESS OF FLANGED JOINTS WITH GASKETS FROM THE THERMALLY EXPANDED GRAPHITE MATERIAL "GRAFLEX"

INFORMATION DATA

1. DEVELOPED BY NIIkhimmash, Ukrniikhimmash, VNIIneftemash PERFORMERS: 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.; Zeyde I.E.; Wolfson B.S. 2. APPROVED AND INTRODUCED BY the approval sheet of the Main Scientific and Technical Directorate dated 11/29/88. 4. REFERENCE REGULATIONS AND TECHNICAL DOCUMENTS