35crmo seamless steel pipe

35crmo seamless steel pipe

35CRMO seamless pipe

Oil pipes imported from Japan account for more than half of the total import volume. The largest oil casing production base in China, Tianjin Steel Pipe Company, produced 522000 tons of steel pipes in 2000, of which 364100 tons were oil casings. Casing accounts for over half of the country's oil production. It ranks first in both production and sales volume in the Chinese casing market.

From both international and domestic markets, the existing production capacity of seamless pipes (including petroleum specific pipes) has exceeded demand. Therefore, the focus in the future should be on fully utilizing the capabilities of existing units to develop high-strength, high damage resistant, and high corrosion resistant products such as petroleum pipes, high-pressure boiler pipes, and gas cylinder pipes. This is also the content of the country's optimization of product structure for the current steel market in China. This is also the key to increasing product competitiveness and expanding market share both domestically and internationally. That is to say, improving the market competitiveness of domestic steel pipe enterprises is the long-term task and key to their successful development after joining the WTO.

Seamless pipe production and manufacturing: seamless pipe process flow

Tube blank - inspection - peeling - inspection - heating - perforation - acid washing - grinding - lubrication and air drying - welding head - cold drawing - solid solution treatment - acid washing - acid pickling and passivation - inspection - cold rolling - degreasing - cutting head - air drying - internal polishing - external polishing - inspection - labeling - finished product packaging

seamless tube

1. Production and manufacturing methods

According to different production methods, it can be divided into hot-rolled pipes, cold-rolled pipes, cold drawn pipes, extruded pipes, etc.

1.1 Hot rolled seamless pipes are generally produced on automatic pipe rolling units. The solid tube blank is inspected and surface defects are removed, cut into the required length, centered on the end face of the tube blank perforation, and then sent to the heating furnace for heating, and perforated on the perforation machine. During perforation, while continuously rotating and advancing, under the action of the rolling mill and the top, a cavity gradually forms inside the billet, called a capillary tube. Then send it to the automatic pipe rolling machine for further rolling. Finally, the wall thickness of the entire machine is uniformly adjusted, and the diameter is determined by a sizing machine to meet the specification requirements. The use of continuous rolling mills to produce hot-rolled seamless steel pipes is an advanced method.

1.2. In order to obtain seamless pipes with smaller size and better quality, cold rolling, cold drawing, or a combination of both methods must be used. Cold rolling is usually carried out on a two roll mill, where steel pipes are rolled in a circular hole pattern consisting of a variable cross-section circular groove and a stationary conical top. Cold drawing is usually carried out on single chain or double chain cold drawing machines with a capacity of 0.5-100T.

1.3. The extrusion method involves placing the heated billet in a sealed extrusion cylinder, and moving the perforation rod and extrusion rod together to extrude the extruded part from a smaller die hole. This method can produce steel pipes with smaller diameters.

2. Chemical composition testing

2.1. The chemical composition of domestically produced seamless pipes supplied according to their chemical composition and mechanical properties, such as steel grades 10, 15, 20, 25, 30, 35, 40, 45, and 50, shall comply with the provisions of GB/T699-88. Imported seamless pipes shall be inspected according to the relevant standards stipulated in the contract. The chemical composition of 09MnV, 16Mn, and 15MnV steels shall comply with the provisions of GB1591-79.

2.2. For specific analysis methods, refer to the relevant sections of GB223-84 "Chemical Analysis Methods for Steel and Alloy".

2.3. Refer to GB222-84 "Allowable Deviation of Chemical Composition of Samples and Finished Products for Chemical Analysis of Steel" for analysis of deviations.

3. Physical performance testing

3.1. Domestic seamless pipes supplied according to the performance of the mechanism shall be made of ordinary carbon steel manufactured according to Class A steel in GB/T700-88 (but must ensure that the sulfur content does not exceed 0.050% and the phosphorus content does not exceed 0.045%), and their mechanical properties shall comply with the values specified in Table GB8162-87.

3.2. Domestic seamless pipes supplied according to the hydrostatic test must ensure the hydrostatic test specified in the standard.

3.3. The physical performance inspection of imported seamless pipes shall be carried out in accordance with the relevant standards stipulated in the contract.

2. Application 2.1: Seamless pipes have a wide range of uses. Seamless pipes for general use are rolled from ordinary carbon structural steel, low-alloy structural steel, or alloy structural steel, with the highest production volume, mainly used as pipelines or structural parts for transporting fluids.

2.2. Supply is divided into three categories according to different purposes: a. Supply according to chemical composition and mechanical properties; b、 Supply based on mechanical performance; c、 Supply according to hydraulic pressure test. Steel pipes supplied according to categories A and B, if used to withstand liquid pressure, also need to undergo hydrostatic testing.

2.3. There are various types of seamless pipes for specialized purposes, such as seamless pipes for boilers, seamless pipes for geology, and seamless pipes for petroleum.

3. Types

3.1 Seamless steel pipes can be divided into hot-rolled pipes, cold-rolled pipes, cold drawn pipes, extruded pipes, etc. according to different production methods.

3.2. Classified by appearance, there are circular pipes and irregular pipes. In addition to square and rectangular pipes, there are also elliptical pipes, semi-circular pipes, triangular pipes, hexagonal pipes, convex pipes, plum blossom pipes, etc.

3.3 According to the different materials, it can be divided into ordinary carbon structural pipes, low-alloy structural pipes, high-quality carbon structural pipes, alloy structural pipes, stainless steel pipes, etc.

3.4 According to specific purposes, there are boiler pipes, geological pipes, petroleum pipes, etc.

4. Specification and appearance quality

Seamless pipe according to GB/T8162-87

4.1 Specifications: Hot rolled tube outer diameter 32-630mm. Wall thickness 2.5-75mm. Cold rolled (cold drawn) tube outer diameter 5-200mm. Wall thickness 2.5-12mm.

4.2 Appearance quality: The inner and outer surfaces of the steel pipe shall not have defects such as cracks, folds, rolling folds, delamination, hairlines, and scars. These defects should be completely removed, and after removal, the wall thickness and outer diameter should not exceed negative deviations.

4.3 The two ends of the steel pipe should be cut at right angles and any burrs should be removed. Steel pipes with a wall thickness greater than 20mm are allowed to be cut by gas cutting and hot sawing. According to the agreement between the supply and demand sides, there is no need to cut off the head.

4.4. Cold drawn or cold-rolled precision seamless steel pipes shall refer to GB3639-83 for their surface quality.

5. Packaging

According to GB2102-88 regulations. There are three types of steel pipe packaging: bundling, boxing, and oiled bundling or oiled boxing.

Seamless pipe

Application of 35CRMO seamless pipe and ordinary steel pipe

1. Seamless steel pipes for fluids: GB8163-99

2. Seamless steel pipes for boilers: GB3087-1999

3. High pressure seamless pipe for boilers: GB5310-95 (ST45.8-III type)

4. High pressure seamless steel pipes for fertilizer equipment: GB6479-1999

5. Seamless steel pipe for geological drilling: YB235-70

6. Seamless steel pipe for oil drilling: YB528-65

7. Seamless steel pipes for petroleum cracking: GB9948-88

8. Seamless pipe for petroleum drill collar: YB691-70

9. Seamless steel pipes for automotive half axles: GB3088-1999

10. Seamless steel pipes for ships: GB5312-1999

11. Cold drawn and cold-rolled precision seamless steel pipes: GB3639-1999 Various alloy pipes 16Mn, 27SiMn, 15CrMo, 35CrMo, 12CrMov, 20G, 40Cr, 12Cr1MoV, 15CrMo steel pipes are divided into seamless steel pipes and welded steel pipes according to different production processes. Seamless steel pipe is a seamless steel pipe made by piercing steel ingots, billets, or bars. Mainly used for hydraulic support steel pipes.