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Using spray shot derusting several problems should be paid attention to

The basic ways of high-pressure boiler steel pipe derusting:

cleaning: use solvent, emulsion high-pressure boiler steel pipe surface cleaning, to remove oil, grease, dirt, lubricants, and similar organic matter, but it cannot remove high-pressure boiler steel pipe surface rust, scale, welding flux, etc., therefore in the production of anti-corrosion only as a supplementary Stainless Steel Flues Suppliers means.

[2] tool cleaning: mainly USES steel wire brush and other tools of high-pressure boiler steel pipe surface grinding, can remove loose or cock scale, rust, slag, etc. Hand tools can achieve derusting Sa2 level, power tool cleaning can reach grade Sa3, if a high-pressure boiler steel pipe firmly adhered on the surface of iron oxide, tool cleaning effect is not ideal, anchor pattern depth of anticorrosion construction requirements

[3] pickling: generally do with two methods of chemical and electrolytic pickling process, pipeline corrosion protection using chemical pickling, can remove scale, rust, old coating, sometimes can be used as sandblasting derusting after reprocessing. Chemical cleaning while can make the surface reaches a certain cleanness and roughness, but the anchor lines shallow, and easy to damage to the environment.

[4] shot derusting spray (cast) : shot derusting spray (cast) is driven by high-power motor spray (cast) shoot high-speed rotating blades, make steel grit, steel shot, segment, minerals and other abrasive wire under the action of centrifugal force on steel pipe surface spray (cast) processing, not only can thoroughly remove rust, oxides and dirt, and high-pressure boiler steel pipe under the action of abrasive violent impact and friction, also can achieve the required uniform roughness.

After shot derusting spray (left), not only can enlarge the physical adsorption on the surface of the pipe, and can enhance anti-corrosion layer and mechanical adhesion on the surface of the pipe. Therefore, shot derusting spray (cast) is an ideal cleaning pipeline corrosion protection method. In general, shot peening (sand) is mainly used for high pressure boiler steel pipe derusting surface treatment, shot (sand) is mainly used for pipe derusting outside surface treatment. Using spray (cast) shot derusting several problems should be paid attention to.

With the development of the current our country economy, long distance oil and gas pipeline is an important means of energy security, in the process of oil (gas) pipeline anticorrosion construction, high pressure boiler tube surface derusting also led to the life they use factor. To ensure the quality of the anticorrosive coating, on the basis of the same equipment, improve the technological level, reduce the production cost.

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Samples were taken from the visible part of the crack

erw steel pipeThe composition of rare-earth sulfide and rare earth oxide layer in the steel were determined by microanalysis of inclusions. Inclusion is the main reason for the formation of cracks, band-shaped inclusions in the high temperature and the role of welding pressure within the separation cracks.

In recent years, the rapid development of 's oil industry, especially in the western development / West-East Gas Pipeline project implementation, extensive use of low-alloy high-strength steel, welding production of large diameter oil or gas pipeline, in order to ensure a high pipeline Shear breaking capacity, requiring high resistance to transverse tear steel plate capacity. How to improve the purity of steel and the deformation of sulfide is not deformed, as the steel production enterprises of the core technology issues. X52 pipeline steel is currently 's oil and gas transmission commonly used steel welding steel, generally take calcium to reduce the sulfur content of steel, phosphorus and other impurities, reduce the total amount of inclusions in steel; or add rare earth in steel to Horizontal flue kits achieve Spheroidized sulfides to prevent the formation of long strip MnS inclusions, the two production processes have achieved good results.

X52 test coil edge along the rolling direction of double-sided magnetic particle inspection, the results did not find an alarm phenomenon. The results show that there are no cracks and other defects before the high frequency welding. The cracks in the heat affected zone of the welded pipe occur during the welding process, and the possibility of cracking from the X52 test coil is eliminated. The microstructure and crack morphology of X52 test steel pipe were sampled horizontally after sampling. The X52 erw steel pipe and coil were sampled longitudinally and inclusions were graded.

The welding crack is located in the weld heat affected zone of the inner wall of X52 pipe, about 15 ~ 210mm away from the weld, the crack trend is consistent with the metal flow line of the welded joint, showing a slight bending state, there are inclusions in the crack, indicating the crack generation and welding squeeze Pressure and inclusions. Samples were taken from the visible part of the crack and pressed along the crack to produce an electron microscope fracture specimen. Crack fracture is cracked from the crack side of the force to expand the fracture and the fracture can be seen on the old and has oxidized black crack source area, and sample preparation of tearing fibrous expansion zone two obvious areas. The depth of the crack source area is generally about 110 ~ 210mm, the length of some reach 100mm, some only 310 ~ 510mm, different lengths.

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SSAW steel pipe is strip steel coil as the raw material

SSAW steel pipe is strip steel coil as the raw material, warm-extruded, and welded by an automatic double-wire double-sided submerged arc welding process.

(1) The raw materials are strip coil, welding wire, and flux. Before going through the strict physical and chemical tests.

(2) Strip steel head-to-tail butt joint, single wire or double wire submerged arc welding, automatic submerged arc welding repair welding after rolling into steel pipe.

(3) Before forming, the strip is subjected to leveling, trimming, planing, surface cleaning and pre-bending.

(4) The electric contact pressure gauge is used to control the pressure of the cylinder on both sides of the conveyor to ensure the smooth conveyance of the strip.

(5) Roller molding with external control or internal control.

(6) Weld gap control device is used to ensure that the weld gap meets the welding requirements, and the pipe diameter, misalignment and weld gap are strictly controlled.

(7) Both internal and external welding are performed by single- or double-wire submerged arc welding using the Lincoln welding machine in the United States, so as to obtain stable welding specifications.

(8) The welded seams are inspected by an online continuous Aluminum condensing flue ultrasonic automatic flaw detector to ensure 100% non-destructive testing coverage of spiral welds. If there is a defect, it will automatically alarm and spray the mark, and the production workers will adjust the process parameters at any time to eliminate the defect in time.

(9) The stel pipe is cut into individual pieces by an air plasma cutting machine.

(10) After cutting into a single steel pipe, each batch of steel pipes must undergo a strict first inspection system to check the mechanical properties, chemical composition, fusion status, surface quality of the steel pipe and non-destructive inspection to ensure that the pipe manufacturing process is qualified. Only then can it be officially put into production.

(11) The parts with continuous sonic flaw detection marks on the welds are reviewed by manual ultrasonic and X-rays. If there are defects, after repairing, they undergo non-destructive inspection again until it is confirmed that the defects have been eliminated.

(12) All pipes where steel butt welds and tee joints intersect with spiral welds are inspected by X-ray television or film.

(13) Each steel pipe is subjected to a hydrostatic test, and the pressure is radial sealed. The test pressure and time are strictly controlled by the steel tube hydraulic pressure testing device. The test parameters are printed automatically.

(14) The pipe end is machined to accurately control the end face verticality, bevel angle and blunt side.

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Small diameter cold drawn precision steel pipe

Small diameter cold drawn precision steel pipe: it is used in the mechanical structure, the size of the hydraulic equipment of high precision and good surface finish of seamless steel tube. Seamless steel pipe must adopt the method of cold rolling, cold drawing or both combined. Cold drawing usually in 0.5 ~ 100 t single or double chain chain cold drawing machine. High-quality small cold drawn steel tube is mainly used for 10, 20, steel manufacturing, in addition to guarantee the chemical composition and mechanical properties to do water pressure test, edge, flaring, flattening test, etc.

The classification of small cold drawn steel tube:

1, GB/T8162-1999 (structure with seamless steel tube). Mainly used for the general structure and the mechanical structure. It represents material (brand) : carbon steel, 45 Flue adaptors steel 20; Alloy steel Q345, 20 crmo 20 cr, cr, 40, 30-35 crmo, 42 crmo, etc.

2, GB/T8163-1999 small cold drawn steel tube (transmission fluid with seamless steel tube). Mainly used in engineering and large equipment in pipes conveying fluid. On behalf of the material (brand) of 20, Q345, etc.

3, GB3087-1999 (low intermediate pressure boiler seamless steel tube). Mainly used in industrial boiler and boiler of low intermediate pressure fluid pipe life. On behalf of the material for 10, 20 steel.

4, GB5310-1995 (high pressure boiler seamless steel tube). Is mainly used for power plant and nuclear power plant boiler high temperature resistant, high voltage transmission fluid collection box and the pipeline. On behalf of the material of 20 g, 12 cr1movg, 15 crmog, etc.

5, GB5312-1999 (ship with carbon steel and carbon manganese steel seamless steel tube). Mainly used for Marine boiler and overheating is used the I and class II pressure tube, etc. On behalf of the material for 360, 410, 460, steel grade, etc.

6, GB1479-2000 (high pressure chemical fertilizer equipment with seamless steel tube). Mainly used for fertilizer equipment in high temperature and high pressure liquid pipeline. On behalf of the material for 20, 16 mn, 12 crmo, 12 cr2mo, etc.

7, GB9948-1988 (seamless steel tube used in oil cracking). Mainly used in oil refineries in the boiler, heat exchangers and pipe conveying fluid. Its representative material of 20, 12 crmo, 1 cr5mo, 1 cr19ni11nb, etc.

8, GB18248-2000 (cylinders with seamless steel tube). Mainly used for making all kinds of gas, hydraulic cylinders. It represents material for 37 mn, 34 mn2v, 35 crmo, etc.

9, GB/T17396-1998 (hydraulic prop with hot rolled seamless steel tube). Is used mainly for coal mining hydraulic support and cylinder, column, and other hydraulic cylinder, column. Its representative material of 20, 45, 27 simn, etc.

10, GB3093-1986 (diesel engine with high-pressure seamless steel tube). High pressure oil pipe is mainly used for diesel injection system. The steel pipe for cold drawn pipe commonly, its representative material to 20 a.

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Toughness index has actually become a pipe line pipe important indicator

Currently, the project is widely used annealed after welding cooling to eliminate residual stress, while cooling after welding residual stress is an important process, this approach is not a waste of energy and easy to produce larger welding residual stresses. Post weld heat treatment is a new technique to eliminate residual stress. After the material is preheated before welding to heat treatment temperature and the welding process to maintain continuous heating of the weld member that temperature after soldering using its thermal insulation cotton allowed to cool slowly. This method can effectively reduce the welding residual stress, improve resistance to stress corrosion of metals. Post weld heat treatment can effectively reduce the welding residual stress, and heat treatment temperature is higher, the China Wholesale Stainless Steel Flues Manufacturers residual stress better. 

After the heat treatment can be effectively improved resistance to stress corrosion spiral welded steel pipe, the higher the heat treatment temperature, stress corrosion resistance increased more significant. Pipeline Industry Development of 's second climax will surely come. Spiral steel pipe (ssaw steel pipe) will be put into research, and enhance the pipeline capacity. Improve and increase the diameter of the intensity level, due to the importance of the people's lack of understanding of the impact toughness of the material, in many parts of the world have occurred fragility and fracture toughness of pipeline accidents. Through the analysis of these incidents, research, and "fracture mechanics" as the development of a new discipline and practical application in the pipeline industry, increasing the awareness of the importance of understanding the impact toughness of the pipe. Toughness index has actually become a pipe line pipe important indicator. 

In fact, the spiral steel pipeline transportation has many advantages, is the resilience of poor transmission capacity shortage. For just freezing point, high waxy crude oil, higher than the designed capacity, the pipeline will be constrained by existing capacity and pressure pumping capacity; below the designed capacity, the pipeline will be constrained by existing thermal conditions. To overcome this fixed point, only with the DRA and depressant. Spiral steel pipe and ductile crack extension instability instability expansion. How to avoid pipeline breaks have a way of base metal and weld flattening test, guided bend test, a number of indicators of landing inspection toughness test, Charpy impact test. Not only for the gas pipeline has a higher toughness requirements for oil pipelines in recent years also made a high impact toughness requirements. For long-distance pipeline, it should completely avoid crack initiation is very difficult, in fact, at home and abroad are difficult to fully achieve. This is because the long-distance pipeline hundreds of kilometers long and some even more than a thousand kilometers long welds, weld too much, plus the damage caused during construction and transportation, etc., so that increases the chances floor room. 

Currently, the project is widely used to eliminate residual stress annealed after welding cooling, and cooling after welding residual stress is an important process, this approach is not a waste of energy and easy to produce larger welding residual stresses. Post weld heat treatment is a new technique to eliminate residual stress. After the material is preheated before welding to heat treatment temperature and the welding process to maintain continuous heating of the weld member that temperature after soldering using its thermal insulation cotton allowed to cool slowly. This method can effectively reduce the welding residual stress, improve resistance to stress corrosion of metals. Post weld heat treatment can effectively reduce the welding residual stress, and heat treatment temperature is higher, the residual stress better. After the heat treatment can be effectively improved resistance to stress corrosion spiral welded steel pipe, the higher the heat treatment temperature, stress corrosion resistance increased more significant. Pipeline Industry Development of 's second climax will surely come. Spiral steel pipe will be put into research, and enhance the pipeline capacity.            

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