Seamless steel pipe GOST 8732-78, GOST 8734-75

Seamless pipe weight. Table.

Seamless steel pipe is manufactured using several methods, namely: rolling, drawing, forging and pressing. This type of pipe has a one-piece design and does not have joining seams along its entire length. There are two types of seamless pipes : hot-rolled (hot-deformed) GOST 8732-78 , manufactured from billets or ingots at high temperatures, using one of four methods (given above) and cold-rolled (cold-deformed) GOST 8734-78 , their manufacturing method differs from hot-rolled by lower temperatures.
In cold-rolled production, the finished product has higher quality and precision of the material. The use of this pipe can be different from mechanical engineering to public utilities. Most often, the seamless type of pipe, due to its strength characteristics, is used where high reliability and durability are required (gas, oil pipelines). This type of pipe is economically beneficial, as it has an affordable price on the world market.

Seamless pipes are produced in measured, unmeasured and multiple lengths; their length can range from 4 to 12 meters, in some cases these dimensions are neglected.

Depending on the wall thickness, seamless pipes are divided into thin-walled and thick-walled. They are expressed as the ratio of the outer diameter of the pipe to the thickness of its wall. If this coefficient lies in the range from 6 to 12.5, then such a pipe is considered thick-walled, and if from 12.5 to 40, then it is considered thin-walled.

It happens that this coefficient is less than 6; such a pipe is called “extra thick-walled”.

Requirements for seamless cold-formed steel products

According to GOST, seamless steel pipes are manufactured with an outer diameter from 5 to 250 mm and a wall thickness from 0.3 to 24 mm. They can be:

• unmeasured length from 1.5 to 11.5 m;
• measured length from 4.5 to 9 m with maximum length deviations of +10 mm;
• a multiple of the cut length from 1.5 to 9 m with an allowance for each cut of 5 mm (unless another allowance was specified by the customer) and with maximum deviations for the total length not exceeding those specified for cut length pipes.

Weight and range of steel main pipes according to GOST 20295-85

Welded steel pipes for main gas and oil pipelines - GOST 20295-85.

GOST 8732-78 Hot-deformed seamless steel pipes. Assortment

STATE STANDARD OF THE USSR UNION

HOT FORMED SEAMLESS STEEL PIPES

Assortment

GOST 8732-78

STATE STANDARD OF THE USSR UNION

Date of introduction 01/01/79

1. This standard applies to hot-formed seamless steel pipes for general purposes, manufactured in outer diameter, wall thickness and length.

2. The dimensions and weight of 1 m of pipes must correspond to those given in the table. 1

Table 1

Continuation of the table. 1

Continuation of the table. 1

Continuation of the table. 1

Notes:

1. Pipe dimensions taken in brackets should not be used when designing new equipment.

2. The mass of 1 m of pipes is calculated using the formula M =

0.02466
S ( D - S ),
where
D is
the outer diameter, mm;

S—

wall thickness, mm. The density of steel is taken to be 7.850 g/cm3.

3. Pipes, the mass of which is limited by a broken bold line, are manufactured by agreement between the manufacturer and the consumer.

4. Pipes with outer diameters and wall thicknesses marked with an asterisk are used in contractual legal relations for economic, scientific and technical cooperation.

1, 2. (Changed edition, Amendment No. 2).

3. According to the length of the pipe, the following should be made:

unmeasured length - ranging from 4 to 12.5 m;

measured length - within unmeasured length;

length, a multiple of the measured length - within the unmeasured length with an allowance for each cut of 5 mm;

approximate length - within an unmeasured length.

Notes:

1. By agreement between the manufacturer and the consumer, it is allowed to produce pipes with lengths beyond the limits specified for pipes of irregular length.

2. For pipes with a wall thickness of more than 16 mm, the length of the measuring pipes is established by agreement between the manufacturer and the consumer.

3. Pipes of approximate length are manufactured according to customer requirements.

4. Maximum deviations along the length of pipes of the measured length and lengths that are multiples of the measured length should not exceed: +10 mm - for a length of up to 6 m; +15 mm - with a length of more than 6 m or with an outer diameter of more than 152 mm; ±500mm is for approximate length.

3, 4. (Changed edition, Amendment No. 1).

5. Maximum deviations in the outer diameter and wall thickness of pipes should not exceed those indicated in the table. 2 and 3.

table 2

Table 3

6. By agreement between the manufacturer and the consumer, pipes can be manufactured with combined maximum deviations, for example: for the outer diameter of increased accuracy according to GOST 9567, and for wall thickness - normal accuracy, etc.

7. Ovality and variation in wall thickness of pipes should not take the size of the pipes beyond the maximum deviations in diameter and wall thickness.

8. The curvature of any pipe section per 1 m of length should not exceed: 1.5 mm - for pipes with a wall thickness of up to 20 mm; 2.0 mm - for pipes with a wall thickness of over 20 to 30 mm; 4.0 mm - for pipes with a wall thickness of over 30 mm.

9. At the consumer’s request, pipes must be supplied by internal diameter and wall thickness, as well as by external and internal diameters and by wall thickness.

Maximum deviations in the internal diameter for pipes with a diameter of 70-203 mm, a wall of 7-20 mm and a ratio of diameter to wall thickness equal to or less than 10 should not exceed the corresponding maximum deviations in the outer diameter indicated in Table. 2.

For other pipe sizes, maximum deviations in internal diameter are established by agreement between the manufacturer and the consumer.

Examples of symbols

A pipe with an outer diameter of 70 mm, a wall thickness of 3.5 mm, a length that is a multiple of 1250 mm, of normal manufacturing precision, from steel grade 10, is manufactured according to group B of GOST 8731:

A pipe with an outer diameter of 70 mm, a wall thickness of 3.5 mm, a length of 6000 mm (measured length), increased manufacturing precision, from steel grade 40X, is manufactured according to group B of GOST 8731:

The same thing, of unmeasured length, is manufactured according to group D of GOST 8731:

A pipe with an outer diameter of 219 mm, a wall thickness of 10 mm, of unmeasured length, normal manufacturing precision, made of steel grade St4sp, steel category 1, manufactured according to group B of GOST 8731 from an ingot:

A pipe with an internal diameter of 70 mm, a wall thickness of 3.5 mm, a length of 6000 mm (measurement length), of normal manufacturing precision, from steel grade 10, is manufactured according to group B of GOST 8731:

A pipe with an outer diameter of 95 mm, an inner diameter of 76 mm, permissible differences in thickness of unmeasured length, normal manufacturing accuracy, from steel grade 10, is manufactured according to group B of GOST 8731:

(Changed edition, Amendment No. 2).

10. Technical requirements - according to GOST 8731.

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the USSR Ministry of Ferrous Metallurgy

DEVELOPERS

A. A. Shevchenko, Doctor of Engineering. sciences; V. P. Sokurenko, Ph.D. tech. sciences; V. N. Rovensky

2. APPROVED AND ENTERED INTO EFFECT by Resolution of the State Committee of Standards of the Council of Ministers of the USSR dated March 22, 1978 No. 757

3. INSTEAD GOST 8732-70

4. The standard fully complies with ST SEV 1481-78

5. REFERENCE REGULATIVE AND TECHNICAL DOCUMENTS

6. The validity period was lifted according to Protocol No. 3-93 of the Interstate Council for Standardization, Metrology and Certification (IUS 5-6-93)

7. REISSUE with Amendments No. 1, 2, approved in February 1982, September 1988 (IUS 5-82, 1-89)

Features of installation and connection

The type of installation and connection of seamless pipes directly depends on the wall thickness, but welding has proven itself to be the most effective and reliable connection. In this case, the ends of the product must be cut off - this way the seam will interact better with the surface.

Thin-walled products are welded with a gas welding machine - it allows even a beginner to carry out the work accurately.

But pipes with walls 20 mm thick or more are welded exclusively by electric welding - the power of the gas apparatus is too weak.

Hot-deformed pipes according to GOST 8732 78 can be bent using mechanical pipe benders, if required by the design in which they are used.

Production technology

Seamless pipes are produced using various rolling technologies. The blank for their production is a monolithic material in the shape of a cylinder. The purpose of the products depends on the type of metal that is part of the alloy. The production process itself is technically quite complex, which affects their cost. The technology for manufacturing seamless pipes makes them easy to process. They lend themselves well to welding, riveting, and cutting.

We produce seamless hot-deformed pipes for both general and special purposes from carbon, alloy or low-alloy steel. The production process of its manufacture has its own characteristics.

The workpiece is heated to a temperature exceeding the steel crystallization threshold by 55 - 60º C. In this case, the part becomes more plastic.

On a piercing machine, a hollow cylinder comes out of a heated workpiece.

Rolling ensures the correct geometric shape. During the deformation process, a hot-rolled seamless steel pipe acquires the required wall thickness and outer diameter.

The finished product is cooled (immersed in water). Then, when passing through the rollers, its final calibration is carried out.

The processing is completed by cutting pipes of standard length.

The technology for producing cold-deformed seamless pipes mainly has two differences. First, cooling is carried out after passing through the piercing mill. Second, the preliminary calibration step is performed in a cold state. Before the liner is finally driven through the rollers, it is annealed and heated to a temperature at which the steel recrystallizes. This is done for the viscosity and ductility of the metal.

Pros and cons of seamless drawn pipes

These pipes have few disadvantages, the main one is the huge price for 1 ton of product. But many buyers are interested in something else, the absence of a seam, the plus or minus of this building material.

In fact, this is the main advantage, because it allows for high strength and tightness over the entire surface, low weight, and excellent wear resistance. Solid-drawn blanks are actively used in many areas, even in aircraft manufacturing, which indicates their reliability.