Mechanical properties of tubing of steel strength groups

Main indicators of pipe steel strength groups

Pump pipes

Strength characteristics of rods and conditions of their use

Frequent lowering and lifting of rods leads to an increase in the frequency of rod breaks. Relevant instructions regulate the rules for storing, transporting and assembling rods and rod columns.

Tubing pipes (tubing) come with smooth and upset (equal strength) ends. Pipes with smooth ends have a constant diameter along their length and therefore are somewhat weakened in the places where they are cut for coupling joints. Pipes with exposed ends have thicker ends where they are cut for coupling joints and therefore have increased strength of the cut part of the pipe.

According to the length of the tubing, they are divided into three groups: 1 - from 5.5 to 8 m; II - 8 - 8.5 m; III - 8.5 - 10 m.

Pipes are made from steels of five strength groups: D, K, E, L, M. Smooth pipes and couplings for them of strength groups K, E, L, M, as well as all pipes with upset ends are subject to heat treatment (Table 10.3).

Table 10.3

The main characteristics of tubing used in oil production are given in Table. 10.4. The nominal diameter of the pipe coincides with the outer diameter of the pipe body to within a few tenths of a millimeter.

Tubing in wells, especially with SSNU, carry a heavy load. In addition to stretching due to their own weight, they are subject to load from the weight of the liquid column filling the tubing, and sometimes from the weight of the rod string when they break at the top or when the plunger is seated on the suction valve rod. In curved wells they are subject to friction by rod couplings. At high back pressures at the wellhead, a force is added equal to the product of the wellhead pressure and the pipe area (in the open). Typically, the safety factor is taken to be 1.3 - 1.5, based on the load corresponding to the yield stress σt.

Pipes are marked at the coupling end. The stamp indicates the nominal diameter, wall thickness (mm), plant trademark, strength group (letter), month and year of manufacture. Wall thickness is indicated only for pipes 73 and 89 mm, of which there can be two (see Table 10.4).

Table 10.4

Pump pipes

Strength characteristics of rods and conditions of their use

Frequent lowering and lifting of rods leads to an increase in the frequency of rod breaks. Relevant instructions regulate the rules for storing, transporting and assembling rods and rod columns.

Tubing pipes (tubing) come with smooth and upset (equal strength) ends. Pipes with smooth ends have a constant diameter along their length and therefore are somewhat weakened in the places where they are cut for coupling joints. Pipes with exposed ends have thicker ends where they are cut for coupling joints and therefore have increased strength of the cut part of the pipe.

According to the length of the tubing, they are divided into three groups: 1 - from 5.5 to 8 m; II - 8 - 8.5 m; III - 8.5 - 10 m.

Pipes are made from steels of five strength groups: D, K, E, L, M. Smooth pipes and couplings for them of strength groups K, E, L, M, as well as all pipes with upset ends are subject to heat treatment (Table 10.3).

Table 10.3

The main characteristics of tubing used in oil production are given in Table. 10.4. The nominal diameter of the pipe coincides with the outer diameter of the pipe body to within a few tenths of a millimeter.

Tubing in wells, especially with SSNU, carry a heavy load. In addition to stretching due to their own weight, they are subject to load from the weight of the liquid column filling the tubing, and sometimes from the weight of the rod string when they break at the top or when the plunger is seated on the suction valve rod. In curved wells they are subject to friction by rod couplings. At high back pressures at the wellhead, a force is added equal to the product of the wellhead pressure and the pipe area (in the open). Typically, the safety factor is taken to be 1.3 - 1.5, based on the load corresponding to the yield stress σt.

Pipes are marked at the coupling end. The stamp indicates the nominal diameter, wall thickness (mm), plant trademark, strength group (letter), month and year of manufacture. Wall thickness is indicated only for pipes 73 and 89 mm, of which there can be two (see Table 10.4).

Table 10.4

GOST 16523-89

Technical Requirements

For thin sheet hot-rolled and cold-rolled carbon steel of high-quality and ordinary quality for general purpose, manufactured with a width of 500 mm or more, a thickness of up to 3.9 mm inclusive.

Rentals are divided into:

• by production method:

• hot rolled,
• cold rolled;
• sheets,
• rolls;
• cold rolled: especially high finishing - I,
• high finish - II,
• advanced finishing - III (IIIa, IIIb);
• hot rolled: high finish - III,
• regular finishing - IV;
• deep - G,
• normal - N.

• by type of product:

• according to the minimum value of tensile strength (B) for strength groups: K260V, K270V, K300V, K310V, K330V, K350, OK360V, OK370V, K390V, OK400V, K490V;
• according to standardized characteristics into categories: 1, 2, 3, 4, 5, 6;
• by quality of surface finishing into groups:

• by drawing ability (cold-rolled steel up to 2 mm thick, strength groups K260V, K270V, K310V, K330V, K350V):

In terms of product range, rolled products must comply with the requirements of GOST 19903 hot-rolled, GOST 19904 cold-rolled. Rolled products are produced:

• made of carbon steel of ordinary quality of strength groups OK300V, OK360V, OK370V, OK400V;
• made of high-quality carbon steel of strength groups K260V, K270V, K310V, K330V, K350V, K390V, K490V. Steel grades and chemical composition requirements for each strength group are given in Table 1.

Table 1

Steel grades used and chemical composition requirements

The weldability of rolled steel of strength groups OK300V and OK360V, OK370V categories 4 and 5 is ensured by the manufacturing technology and chemical composition of the steel. Categories of rental depending on the standardized characteristics are given in Table 2.

table 2

The mechanical properties of rolled products and the diameter of the mandrel when tested for 180-degree bending in a cold state must comply with the requirements of Table 3.

Table 3

There should be no tears, cracks or delaminations at the bend. Hot-rolled steel is produced by heat treatment, cold-rolled steel is produced by heat treatment and tempering. Hot-rolled steel from continuous rolling mills may be produced without heat treatment. Hot-rolled steel is produced with both pickled and unetched surfaces. Sheets must be cut on all sides. Sheets obtained from coils rolled on continuous rolling mills may be manufactured with uncut edges, except for cases specified in the order. Rolled products are produced with unedged and trimmed edges. Defects are not allowed on the edges, the depth of which exceeds half the maximum deviation along the width of the rolled product, and which would take it beyond the nominal width size. Rolled products should not have ends and edges turned at an angle of more than 90 degrees. The length of part-width rolls should not exceed the width of the roll. The depth of the hole during the extrusion test must comply with the requirements of Table 4

Table 4

The surface of cold-rolled steel must be free of films, through breaks, blistering bubbles, rolled bubbles, adhesion-welding spots, cuts, tears, rolled-in scale, over-etched, under-etched, cold-working stripes, rolled-in metal and foreign particles. Layering is not allowed. The same is true for hot-rolled steel. An unetched surface may retain a non-removable layer of scale, allowing surface defects to be identified. Characteristics of the quality of surface finishing are given in Table 5.

Table 5

Characteristics of the quality of surface finishing are given in Table 6.

Table 6