• Hydrostatic Pressure Testing of Pipes

    Hydrostatic pressure test is conducted using a method for static characteristics of rock deformation measurement indicators. Hydrostatic pressure test is a test. When the pressure vessel is made, after the newly installed container 3 prior to use or access, in order to test the strength of the container macro (if there is a crack, if the deformation is too large) and sealing the sealing point and weld, adding an appropriate amount of water in the container. Determination of rock Excavation in Rock a circular tunnel test, the test tunnel test section at one end portion is closed up concrete decking, using a high pressure water pump is forced into the test tunnel, so try cave rock surface subjected to a uniform water pressure caused rock deformation test changes again Underground radius or diameter, and then the relationship between pressure and deformation calculated deformation modulus and elastic resistance of rocks. Determination of pressure parts Usually closed pressurized parts, pressure parts of 1.25 or 1.5 times the design pressure of the injection pressure test water. When observed at least within 30min no leakage or no leakage through the joining surfaces of the cabinet or enclosure, the test is considered satisfactory. Large thick-walled castings may require a longer test time.
  • Difference between ERW and EFW

    ERW is the first letter abbreviation for electric resistance welding. ERW tube and submerged arc welding pipe significantly different, using a pressure-free filler metal welding, the weld is not filled with other ingredients, relying on high-frequency current skin effect and proximity effect, instantly heating the plate edge to welding temperature by squeezing rollers squeeze formed weld forging organizations. High-quality steel pipe welds require online or off-line heat treatment, welding zone structure refinement, quality ERW pipe welds and base metal can reach the same level of toughness, which is submerged arc welding process can not be achieved.   EFW namely electric fusion welding of the first letter abbreviation. Submerged arc welding (SAW) - Electric welding (EFW) one, is through one or more consumable electrodes between the workpiece and the heating of the metal between the metal binding of a process, the arc and the metal filling material melted sufficiently, no pressure, filling the metal part of work-all from the electrodes.   Melting gas shielded arc welding (GMAW) - Electric welding (EFW) A, similar to this process and submerged arc welding, but it is protected from the inert gas, the effect will be better.
  • Oil Casing Folding Defects Solutions

    Casing in the production prone to outer folding defects, affect product quality improvement, it needs to be controlled. There are several outer folding edge oxide particles cause segregation of elements, with a folding, an oxide middle folding, the presence of an excess of Al, Mg, Ca, S, P, Mn, Si outer folding element, particularly at the grain boundaries have 20μm so brittle inclusions SiO2 and silicates, intergranular fracture occurs, and said brittle inclusions is the main reason for the formation of the outer fold. Smelting process: 0.10%; 2) Increase the effect of converter slag, slag under strict control, the departure process using slag, a steel ladle slag after thickness <50mm; 3) Double slag operation, control phosphorus content of the molten steel. Refining process: 1) LF refining processing time ≥20min; 2) Strengthening deoxy go mixed results. Requirements refining slag basicity ≥2.5, slag ≤1%, white residue retention time ≥15min; 3) After the end of the bottom blowing argon refining to ensure soft blowing time ≥10min, to facilitate removal of molten steel inclusions. Casting process: 1) Using a ladle, tundish, protective casting and seal argon, oxidation-free protective casting; 2) Casting temperature: tundish superheat less than 20 ℃; 3) The use of mold level brake control, electromagnetic stirring; 4) Using special flux, to ensure the quality of the slab surface. Finishing processes: To reduce the white spots caused by hydrogen induced cracking deal billets and bars the use of slow cooling process.
  • Advantages of LSAW Steel Pipe

    In the long-distance pipeline construction, pipe-line account for a large proportion, generally 35% to 40% of line pipe accounts for investment projects total investment. How to choose a reasonable price, excellent performance pipe is particularly important to a reasonable choice of pipe to save construction investment, easy construction and safe operation of the pipeline system has a very important influence. Gas Pipelines straight seam steel high-frequency electric resistance welded steel pipe, spiral submerged arc welded pipe, LSAW steel pipe. Limited frequency straight seam electric resistance welded steel pipe diameter range is generally limited to domestic steel Φ406.4 mm or less, the largest in Japan has reached a diameter Φ508mm. For large diameter pipe in the form of a spiral SAW, LSAW two kinds. Spiral welded steel pipe because the pipe forming process and characteristics of many shortcomings, the proportion is gradually declining in the long-distance pipeline. In other countries, especially in many European countries, it has banned the use of spiral submerged arc welded pipe used as the main line pipe. The advantage of its unique LSAW are widely used in long-distance oil and gas pipelines, and its advantages are as follows. (1) Without unwind process, the base material indentation, scratch less. (2) The wrong side of the slit, the diameter perimeter of easy control and excellent welding quality. (3) Elimination of the pipe expansion substantially no residual stress after stress. (4) Because it is a straight line weld, the weld is short, so a small probability of occurrence of defects. (5) After expanding, pipe geometry accuracy is improved greatly facilitates the site welding. (6) A straight line weld, less impact on the quality of anti-corrosion coating material.
  • Points of Heating Welding Tube

    Pipe processing step requires strict, in which the hot rolling process is very important process, in which to introduce the following precautions during the heating pipe. 1, the pipe must be able to feed one of those metal properties were a good understanding Before rolling, when the deforming force is relatively low during the hot-rolled steel is very easy. But for the pipe material which still contains some ingot, so prior to hot rolling must be able to carry out some of them to eliminate those ingots, making it the organizational capacity and resilience are able to get some improvement, and also the pipe during the hot rolling process also will get a lot of protection. 2, be sure to pay attention to each pipe section has a temperature uniformity in all directions during the hot rolling process, so that the pipe can better meet the requirements of the various technological aspects in later. In addition, the heating pipe is will affect a very important reason for the life of the pipe. 3, on the pipe during the heating process in which there will be a lot less than expected occurrence of the accident, and therefore in the process of working among them must be taken to minimize the occurrence of these accidents. 4, for each indicator heating process and the technical requirements are able to do a comprehensive preparatory work, thus extending the life of the pipe. 5, the pipe in the heating process which will be very easy to cause oxidative phenomena pipe, thus there will be some for the original weight loss, so before heating must be able to take into account the reasons.
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