Seamless steel pipe is a very sophisticated production process of steel, steel pipe is a better one, it is widely used in the market.We all know that the equipment or seamless steel pipe is there will be some Problem, then we need to use tools to detect, but in the process of testing seamless steel pipe, we found that there will be some errors, then why would such an error, you can analyze from several aspects. First of all should be due to the cause of the flaw detection equipment, the general testing equipment in the detection of the time is the need to use the probe, and the performance of the probe will have an impact on the detection results.In addition, the type of probe there are the size of the incident angle and the wafer The size of the equipment will be affected by the performance of the equipment, if the performance is not good, then there will certainly be errors in the detection, and there is time because of the reasons for the steel pipe itself caused by the error, May affect the normal inspection, diameter will also have an impact on the detection.

API Standard - API is the American Petroleum Institute (American Petroleum Institute) the English abbreviation. API was built in 1919, is the first national business associations in the United States, is the world's first and most successful standards of the Chamber of Commerce. One of the key tasks of the API is to be responsible for the standardization of equipment for oil and gas industry equipment to ensure the safety, reliability and interchangeability of the equipment used in the industry. The development of coordination standards is one of the earliest and most successful projects in the API. Since the first standard was released in 1924, the API has now released 500 standards. API is an ANSI-accredited standard-setting body whose standards are developed in accordance with ANSI's harmonization and development guidelines, and APIs are jointly developed and published in conjunction with ASTM. In addition, APIs actively participate in the development of ISO standards for global industry, ISO / TC 671SC9 Wellhead Equipment and Pipeline Valve Secretariat. API standards are widely used not only in domestic companies, but also by US federal and state laws and regulations, as well as the Ministry of Transport, the Ministry of Defense, the Occupational Safety and Health Administration, the US Customs, the Environmental Protection Agency, the US Geological Survey and other government agencies, and But also in the world by the ISO, the international legal system of measurement and more than 100 national standards cited. API standards are mainly defined equipment performance, and sometimes include design and process specifications, standard development areas including oil production, refining, measurement, transportation, sales, safety and fire prevention, environmental regulations, and its information technology standards, including oil and gas industry EDI , Communications and information technology applications and so on. API in the United States and other countries in the world have enjoyed a high reputation, it is the US Department of Commerce and the US Trade Commission recognized the oil machinery certification body. It has developed petrochemical and oil extraction machinery technical standards adopted by many countries, the Middle East, South America and many Asian countries in the tender procurement of petroleum machinery, the general requirements of the API logo products eligible to participate in the tender. Therefore, oil machinery with API logo is not only considered to be reliable and advanced. At present, there are members from all over the world, including all aspects of exploration and production, transportation, refining and marketing. Today, the API has evolved into an integral part of the world's oil industry, not only in the United States, but also increasingly.

① Delivery status Refers to the final plastic deformation of the delivery product or the state of the final heat treatment. It is said that the heat treatment is not heat-treated or it is called hot-rolled or cold-drawn (rolled) state or manufacturing state. The heat treatment is heat-treated or heat-treated, normalized, status. When ordering, the delivery status should be indicated in the contract. ② Deliver by actual weight or according to the theoretical weight Actual weight - when delivered, the weight of the product is delivered by weight (weighing) Theoretical weight - When delivered, the weight of the product is calculated from the nominal size of the steel. ③ Vertical and horizontal Standard refers to the vertical direction is the direction of processing (that is, along the direction of processing); horizontal refers to the vertical direction with the processing (the direction of the steel pipe). In the case of an impact test, the fracture of the longitudinal specimen is perpendicular to the machining direction. So that transverse fracture; transverse specimen fracture and processing direction parallel, so that the vertical fracture.

For the straight steel pipe will be gradually rolled into the circle, and the seam welded into steel pipe, according to its production using the welding process can be divided into continuous welding (forging) steel pipe, resistance welding pipe and arc welding key tube three kinds. 1. Continuous welding (forging) riveting, Continuous steel welding (forging)steel pipe is a steel pipe which has a straight seam and heated in the heating furnace and then welded to the formed edges by mechanical pressing. Its characteristics are: high production efficiency, low production costs; but the weld quality is poor, comprehensive mechanical performance is poor. At present, it is mainly applied to the design temperature of 0-100 ℃, the design pressure does not exceed 0.6MPa of water and compressed air system. 2. Resistance bare steel Resistance welding rivet is produced by resistance welding or electric induction welding method, with a straight seam of the steel pipe. Which is characterized by high production efficiency, high degree of automation, welding deformation and residual stress is small; but its high investment in equipment, welding joints of the quality requirements are relatively high; and because the joints are difficult to exist impurities, so the plastic and Low impact toughness. At present, it is mainly applied to the design of water temperature is not higher than 200 ℃, gas, air, heating steam and oil and natural gas industry can be in the reservoir fluid and non-renewable fluid, low pressure pipeline. 3. Arc bad tube The arc welded steel pipe is a steel pipe produced by an arc welding method. Which is characterized by a complete metallurgical combination of joints, mechanical properties of the joints can be fully achieved or to achieve the mechanical properties of the base metal. After proper heat treatment, the use conditions of the arc welding straight seam steel pipe can be replaced by the condition of the seamless steel pipe. At present, it is mainly applicable to the design of the degree of water is not higher than 200 ℃, gas, air, heating steam and other design pressure is less than 5.0MPa pipe.

Carburizing processing of seamless steel pipe, is surface treatment method on seamless steel pipe, the use of carburizing mostly low carbon steel or low alloy steel, the specific method is to place the workpiece with activated carburizing medium, heated to 900--950 degrees celsius single-phase austenite area, soaking enough time, so that carburizing media decomposition of the activated carbon atoms into the steel surface, so as to obtain high-surface surface, the heart still retain the original ingredients. Tempering and the cause of the crack Carburizing layer after grinding the surface caused by the phenomenon of softening, known as the grinding process produced by the tempering. This is due to grinding when the processing feed too fast, grinding wheel hardness and size or speed selection improperly, or grinding process is not sufficient cooling, are prone to such defects. This is because the heat at the time of grinding makes the surface soften. Grinding produces a tempering defect that reduces the wear resistance of the part. The surface of the hexagonal crack, which is because the surface of the hard wheel by excessive grinding, and heat caused. But also with the heat treatment of tempering, residual internal stress is too large. After the acid erosion, any defective parts were black, with no defects to distinguish between. This is the heat generated when grinding is tempered. So that the body of the body into the body of the reason. In fact, the crack can be seen after grinding the naked eye.