The American standard seamless tube is generally similar to the outer diameter micrometer. When measuring and using the inner diameter micrometer, it is necessary to connect the largest size rod to the micrometer to connect the measuring contact to reduce the bending of the connected rear axle; in the measurement, the micrometer head should be observed for fixing and releasing; in daily production, When measuring the hole with the inner diameter ruler, the surface of the contact surface is supported on the surface to be tested, and the differential cylinder is adjusted so that the measuring surface of the differential cylinder is swung to the minimum size in the radial portion of the hole, and then the fixing screw is tightened. And take the reading. Do not tighten the screws to read them directly, so there is a problem with the attitude measurement. Attitude measurement: Consistency between measurement and use. For example, when the inner diameter is 75-600/0.01 mm, the length of the connecting rod and the micro-head is greater than 125 mm, and the difference between the screws when tightening and tightening is 0.8 mm. When measuring the inner diameter micrometer, the support position must be correct. The gravity deformation after the extension of the large inner diameter involves linearity error, parallelism and verticality, and its stiffness can be reflected in the "natural deflection". Theoretical and experimental results show that the cross-sectional shape of the workpiece determines the stiffness has a great influence on the gravity deformation after support. If the inner diameters of the different cross-sectional shapes are the same, when (2/9) L is supported, the measurement error of the inner diameter scale satisfies the requirements, but the support points are slightly different, and the straightness varies greatly. Therefore, in the standard, when the support position is moved to the maximum support distance, the change in straightness is called "natural deflection". In order to ensure rigidity, the support point of the inner diameter ruler in the Chinese standard should be located at the end face (2/9) L and 200 mm, that is, the smallest change of measurement. The inner diameter of the inner diameter is measured at 90 degrees per revolution, indicating that the error should not exceed the requirements.

From the market of thick-walled seamless steel pipe of American Standard Seamless Pipe in October this year, many thick-walled seamless steel pipe manufacturers have better market conditions in October, and the market situation is much better in October than in September. Market prices are also rising steadily. With the continuous upgrading of the industrial structure, the basic form is expected to recover, the industrial overcapacity will accelerate, and the contradictions between industries will become more apparent. From the sub-index, the production index rose by 0.5 percentage points to 50.7%, and remained above the critical point of 50% within four months. The new order index and the purchase price index rose by 5.4 percentage points and 11.7 percentage points respectively, reaching 54.6% and 68.3%, respectively, the highest in nearly six months, and the finished goods inventory index fell by 4.1 percentage points. This is the lowest in nearly six months, and the new export order index has fallen to its lowest level in nearly seven months, even reaching two months. PMI shows that there are currently two high production and sales in the domestic automotive and home appliance industries. The growth of real estate and infrastructure investment has remained at a high level. The domestic market demand for seamless pipes in the United States has been strong, and the rise in thick-walled seamless steel pipes has risen. Pressure and exports are falling. Domestic thick-walled seamless steel pipe market and thick-walled market have become more perfect, and stocks of seamless steel pipe producers have declined. At the same time, domestic coking coal, coke and other raw materials prices continue to rise sharply, the cost of thick-walled seamless steel pipe enterprises has increased significantly, and the post-industry profit situation is not optimistic.