GOST 24950-81

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  ГОСТ 24950-81

GOST 24950−81 Bends and insertion curves on turns the linear part of the steel main pipelines. Specifications

GOST 24950−81

Group B62

INTERSTATE STANDARD

THE BENDS AND INSERTION CURVES ON TURNS THE LINEAR PART OF THE STEEL MAIN PIPELINES

Specifications

Bent branches and elbows at line bends for transmission steel pipelines. Specifications

ISS 23.040.40
GST 11 2001

Date of introduction 1982−07−01

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the Ministry of construction of enterprises of oil and gas industry

2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee for construction from 31.08.81 N 155

3. INTRODUCED FOR THE FIRST TIME

4. REFERENCE AND NORMATIVE-TECHNICAL DOCUMENTS

5 REISSUE. April 2003


This standard applies to bent branches and curved inserts are intended for turning in a vertical or horizontal plane of the linear part of the steel main pipelines and branches from them, manufactured on pipe bending equipment by way of the transverse bending of pipes in a cold condition.

1. TYPES AND BASIC DIMENSIONS

1.1. Bends shall be made of three types:

1 — from one pipe in accordance with the devil.1;

2 — out of pipe with a second inventory period, flexible tube or cartridge extension;

3 — from two pipes in accordance with the devil.2.

Damn.1. The withdrawal of type 1

The withdrawal of type 1

 — outer diameter of the discharge;  — the bending angle of the withdrawal; and  — direct the ends of the branch;  — curved part of the diversion

Damn.1

Damn.2. Withdrawal type 3

Withdrawal type 3

1, 2 — pipe forming a branch;  — external diameter of outlet; ,  — straight ends of branch;  — curved part of the diversion; ,  — straight sections of pipes in the transversal direction of the weld; is the bending angle of the discharge;  — the transverse weld seam connecting the pipes

Damn.2

1.2. Outer diameter, reference thickness, length and deviations from the lengths of pipe are bends, shall be as specified in table.1.

Table 1

1.3. When making bends, the bending angle must be a multiple of 3°. Allowed by agreement between manufacturer and consumer in the manufacture of taps make the bending angle a multiple of 1°.

Deviations from the values of the bending angle of the bends should not exceed ±20'.

1.4. Diameter of laterals, design of unified bending radius and the bending angle of the bends shall be as specified in table.2.

Table 2

1.5. The symbol of the challenge shall consist of: the type designation, the name of the product, bending angle, outside diameter, wall thickness, grade (class) of steel pipes, refer to standard for pipe and of this standard.

Example of designation of type 1 bends with a bending angle of 6° pipe diameter 820 mm, wall thickness 10 mm, pipes as per GOST 20295−85, made of steel grade 17Г1СУ:

1. 6°. 820. 10 — GOST 20295−85-17Г1СУ. GOST 24950−81

1.5. Inserts are divided into three types:

And insert, made of branches of type 1;

Insert A three taps of the type 1 shown in hell.3.

Damn.3. Insertion of the three branches

Insertion of the three branches

1, 2, 3 — taps; , ,  — direct the ends of the fingers;  — transverse weld connecting the bent elbows; , ,  — angles flexible branches;  — the angle of insertion

Damn.3

2. TECHNICAL REQUIREMENTS

2.1. Bends shall be manufactured in accordance with the requirements of this standard.

2.2. Bends must be made from seamless steel pipes with a diameter of 219, 273, 325, 377, 426 mm according to GOST 8733; of longitudinally welded pipes with diameter 219, 273, 325, 377, 426, 530, 720, 820 mm according to GOST 20295 and longitudinally welded pipes with diameters from 219 to 1420 mm according to the specifications approved in the prescribed manner.

2.3. Tolerances for wall thickness of elbows shall conform to tolerances for wall thickness of tubes, which are made from these taps.

2.4. When bending longitudinally welded pipe longitudinal welded seam should be positioned in the neutral plane, the material of the wall in which the bending takes minimum load.

The deviation between the longitudinal welded seam pipes from the neutral plane should not exceed the diameter of the outlet.

2.5. In the manufacture of elbows from pipes with transverse weld sections with a length of not less than 0.5 of the diameter of the pipe about a transverse weld should not be subjected to bending.

2.6. The minimum bending radius at any section of the bent portion of the withdrawal must be at least 40 pipe diameters.

2.7. Flexible bends shall be made when the ambient air temperature is not below minus 20 °C.

2.8. Indicators appearance bends shall conform to the requirements of normative-technical documentation on the straight pipes, which are made from these taps.

Inserts, patches and welding metal in place of damage to drainage prohibited.

Bends must not have cracks, flaws, delaminations, and sunsets. The height of the corrugations, the return shall not exceed the wall thickness of the tube and should not be more than 10 mm.

2.9. The requirements for transverse weld seams at the bends type 3, and inserts from several branches, must comply with GOST 16037 and SNiP III-42.

2.10. Length of branch type 1 or type 2 must be equal to the length of the pipe from which the withdrawal is made, and the length of the diversion type 3 — the length of the two pipes (table.1).

2.11. Tolerances on ovality of bends shall be as given in SNiP III-42.

Before January 1, 1984, it is possible to produce bends with ovality of straight ends no more than 3% and the bent part is not more than 5%.

2.12. The ends of the branches should have a chamfer for welding in accordance with the requirements of normative-technical documentation for pipe, of which manufactured these taps.

3. COMPLETENESS

3.1. By agreement between manufacturer and consumer taps shall be supplied in accordance with the order of the consumer on the value of the bending angle and the insertion tab.1−6 recommended apps.

4. SAFETY REQUIREMENTS

4.1. When bending elbows, mounting, welding and quality control works must be carried out safety requirements set SNiP III-42.

4.2. Loading and unloading, stacking branches in a pile and their transportation must be performed in accordance with the requirements of GOST 12.3.009 and SNiP III-42.

5. ACCEPTANCE RULES

5.1. Bends must be taken technical control of the manufacturer individually in accordance with the requirements of this standard.

5.2. Acceptance of each withdrawal indicators produced by the appearance and length tolerances, the bending angle, the height of corrugation, out-of-round ends straight and bent parts as well as minimum bending radius.

5.3. The data of the manufacturer about the chemical composition and mechanical characteristics of steel pipes, as well as the equivalent carbon and the amount guaranteed by hydraulic pressure pipes are entered in the document about the quality of the taps.

5.4. If unsatisfactory validation results at least one of the indicators of the product is rejected.

5.5. The consumer has the right to make test verification of compliance of diversion requirements of this standard, applying the following test methods.

6. CONTROL METHODS

6.1. To control the linear dimensions of bends should be used roulette according to GOST 7502 and a metal ruler according to GOST 427, and calipers, calipers and other measuring instruments, manufactured according to the standards in this instrument.

6.2. The length of the bends and the deflection of the longitudinal weld from the neutral plane of withdrawal measured with an accuracy of ±50 mm, other sizes — with an accuracy of ±1 mm.

6.3. The length of the withdrawal tape measure along the outer generatrix.

6.4. The deviation between the longitudinal weld of a branch from the neutral plane is measured, a metal line perpendicularly from the longitudinal edges of the frame of the machine to the weld.

6.5. The bending angle of the drainage is checked using an optical quadrant on the other 3−3.179* departmental or measuring devices manufactured according to the drawings approved in the prescribed manner.
________________
* Document authoring is. For additional information, please refer to the link. — Note the manufacturer’s database.

Allowed to verify the bending angle of the outlet for the table.3 three instrumental measured parameters: the length of the chord between the ends of branch (), the height of the arrow from the chord to the inner generatrix of the challenge () and the angle between the chord and a straight pipe, from the side which started it flexible () (damn.4).

Deviations from the dimensions given in table.3, must not exceed:

the length of the chord :

Damn.4. The parameters of the drain to determine the bending angle

The parameters of the drain to determine the bending angle

 — wall thickness of branch (taken across the thickness of the pipe wall);  — diameter of branch (taken on the outside diameter of the pipe);  — bending angle of the discharge;  — the angle between a chord and a straight pipe from the side which started it flexible;  — the length of the chord between the ends of branch;  — the height of the arrow (max) from the chord to the inner generatrix of the withdrawal

Damn.4

Table 3

Dimensions in mm

Extension table 3

Dimensions in mm

Extension table 3

Dimensions in mm

6.6. The minimum allowable bending radius of the withdrawal is checked against the maximum height of the arrow from the chord length of 2000 mm on any curved area on the inner generatrix of the withdrawal (Fig.5) in accordance with the table.4.

Damn. 5. Chord

CL — chord length of 2000 mm in internal forms of diversion; FROM the maximum height arrows on the chord length of 2000 mm to the inner generatrix of the withdrawal

Damn.5

Table 4

mm

6.7. All welded transverse joints of elbows checked visually and non-destructive physical methods of control GOST 18353.

6.8. The magnitude of the ovality of straight ends and curved portion of bends is calculated by the formula

,

where  — maximum diameter, mm;

 — minimum diameter, mm;

 — nominal diameter, mm.

The roundness of the direct ends of the fingers checked at a distance of not more than 250 mm from the ends of the product at the maximum difference of the two mutually perpendicular maximum and minimum diameters.

Ovality of the bent portion is measured in areas of the first and second bends, in the middle of the row and on the site of the last bend.

The step of measuring the ovality of the bent part bends should be:

for branches with a diameter of 219−820 mm is not more than 1 m;

for branches with a diameter of 1020−1420 mm is not more than 1.5 m.

To measure maximum and minimum diameters of bends used a metal ruler and bent parts — departmental measuring instrument made according to the drawings approved in the prescribed manner.

6.9. The height of the corrugation is measured with a caliper and metal ruler with a length of not more than 0.3 outside diameter of the pipe installed on an edge along the tops of the corrugations or single corrugations parallel to the axis of withdrawal, and define a largest gap between withdrawal and lower line.

6.10. The appearance of taps and pipes checked visually.

7. MARKING, TRANSPORTATION AND STORAGE

7.1. On each allotment within the distance of 200 mm from the end of the straight pipe end, which was initiated flexible, put bright paint markings, which must contain the following information:

the type of withdrawal;

the bending angle;

diameter;

the thickness of the wall;

grade of steel;

the sequence number of the withdrawal;

the OTK stamp.

7.2. Transportation of objections are made by any mode of transport. During transportation, loading and unloading of taps needs to be taken that ensures their safety from mechanical damage.

7.3. When transporting by rail the taps loaded on open platforms or open wagons separately by diameter.

7.4. Transportation of bent branches should be made in accordance with the conditions of carriage in railway transport, approved in the established procedure.

7.5. By agreement between manufacturer and consumer taps can be canned or covered with anticorrosive coating.

View preservation or insulation stipulate in the order and noted in the accompanying documentation.

7.6. Manufactured bends must be sorted by the magnitude of the bending angle, diameters, wall thickness and grades and kept no more than two rows horizontally relative to the surface of the earth.

7.7. The shelf life of taps should not exceed one year. After this period, the taps are checked for compliance with the requirements of this standard.

7.8. The manufacturer guarantees the customer the quality and main sizes of taps, specified in this standard, subject to compliance with requirements, loading, unloading, transportation and storage.

7.9. Each outlet shipped from the factory must be accompanied by a document certifying its quality and containing the following data:

name of the organization, which includes the manufacturer of taps;

the name of the manufacturer of taps;

the name of the customer;

the symbol of the withdrawal;

the number of each challenge on the log of the bending operations;

the chemical composition of metal removal;

the mechanical properties of the metal removal;

the equivalent carbon metal drainage;

the amount guaranteed by the hydraulic pressure of the withdrawal;

the designation of the standard or specifications for the pipe material of the outlet.

8. INSTALLATION INSTRUCTIONS

8.1. Inserts with angle of rotation from 3° to 90° and diameters from 219 to 1420 mm must be mounted from the optimal number of taps in accordance with the table.1−6 of the Annex to the standard.

Trimming the straight ends of the fingers during installation of the panels is not allowed.

8.2. Mounting insert of the two or more outlets is accomplished by a coherent set of them in the direction of movement of product through the pipeline, starting with the bends with large bend angles. Each subsequent withdrawal is welded to the previous marked direct end, and the first branch to the pipeline.

8.3. The angle of insertion should correspond to the sum of the angles of flexible branches that make up the insert, and the design rotation angle of the main pipeline.

APPLICATION (recommended). Inserts for pipes with diameter 219−1420 mm

APP
Recommended

The optimum number of taps 219−1420 mm in diameter, which are produced with angles of bending in accordance with table.2, of which a complete insertion with an angle from 3° to 90°, are given in table.1−6.

Example of a record of the insertion And with an angle of 15°, consisting of two bends with a bending angle of 6° and a single outlet with a bending angle of 3°:

A 15°=6°x2+3°.

For inserts with an angle of multiples of 1°, the number of taps should be the same as for the inserts with angle of multiples of 3°, in accordance with the table.1−6.

Table 1

Insertion of bends with a bending angle that is a multiple of 3°, for pipelines with diameters of 219, 273, 325 and 377 mm

Table 2

Insertion of bends with a bending angle that is a multiple of 3°, for tubing with a diameter of 426 mm

Table 3

Insertion of bends with a bending angle that is a multiple of 3° for pipes with diameter of 530 mm

Table 4

Insertion of bends with a bending angle that is a multiple of 3° for pipes with diameter 720 and 820 mm

Note. In table.4−6 in brackets the bending angle of allotment I type.

Table 5

Insertion of bends with a bending angle that is a multiple of 3° for pipes with diameter of 1020 mm

Table 6

Insertion of bends with a bending angle that is a multiple of 3°, for pipelines a diameter of 1220 and 1420 mm