PE water pipe its main chemical molecular composition polyethylene. Learned organic chemistry readers know that the composition of this product is two carbon atoms and five hydrogen atoms, one of the hydrogen atoms and carbon atoms to double bond, and then the single molecule of ethylene for a certain way of polymerization. This product is polyethylene products. So what is the PPR pipe? PPR water pipe is the main component of propylene, that is, three carbon atoms and seven hydrogen atoms, which also has a hydrogen atom and carbon atoms to double bond, and then through the polymerization of the product is formed polypropylene products. This product is almost the same in the health and safety, it is important that the use of raw materials is not in line with the requirements, rather than the two products are different. It is also unfounded to advertise PE water pipes in the newspapers above the PPR water pipes. All qualified PE pipes and PPR tubing products must be hygienically tested (except for those fake and shoddy products). Said PE water pipe is more hygienic and safe than PPR water pipe, but also for consumers to deceive.
Take the oil and gas: After the oil and gas wells have finished and cemented, place oil tubing in the casing to extract oil and gas to the ground.
Water injection: When the underground pressure is not enough, through the oil pipe to the well water.
Steam: In the process of heavy oil thermal recovery, use a insulated oil pipe to enter the steam into the underground.
Acidification and fracturing: in the late drilling or in order to improve the production of oil and gas wells, the need for oil and gas layer of acidification and fracturing of the medium or curing, media and curing products are transported through the oil pipeline.
- The pipe must be open to the end of the pipe before welding. When the weld groove is too small, will cause the pipe wall is not welded, resulting in pipeline welding strength is not enough; when the groove is too large, it will cause cracks, slag and weld defects and other defects. The angle of the groove should be carried out according to the most favorable type of welding in the national standard. The processing of the groove is best to use the groove machine, the use of mechanical cutting method is easy to process the groove, high efficiency, operation and simple, but also to ensure the quality of processing.
- The choice of welding method is related to the construction of the pipeline the most critical part of the need to pay great attention. At present, wide use of oxygen acetylene flame welding, manual arc welding, argon arc welding arc welding two, one of the most suitable way of hydraulic pipe welding is argon arc welding, it has a good quality welding, weld surface smooth, beautiful, No welding slag, welding mouth is not oxidation, high welding efficiency. The other two welding methods easily lead to slag into the tube, or in the weld wall to produce a large number of iron oxide skin, it is difficult to remove. Practice has proved that: once the consequences, in any case, it is difficult to achieve the system cleanliness indicators, so do not easily use. If the construction period is short, argon arc welder, you can consider the use of argon arc welding the first layer (primer), the second layer began to use welding method, which not only ensures the quality, but also improve the construction efficiency.
When the system is made of stainless steel seamless steel pipe, the welding is often used to protect the argon arc welding process. Welding requirements in addition to the outer side of the welding pipe outside the side are sealed, the end of the tube filled with argon, and the welding of the argon arc to the bottom of the arc to fill. In the stainless steel pipe for welding must pay attention to the pipe must be filled with argon, otherwise it will not be able to guarantee the quality of welding. Not according to the welding process requirements of construction, cut the welding area, can be found in the weld was porous sponge body is very irregular. This state of the welding can not guarantee the welding strength, prone to leakage, and filled with argon welding more smooth and dense. Welding current should not be too large, otherwise it will cause the tumor, affecting the flow of oil in the pipeline to cause unnecessary pressure loss.
System flange welding is the difficulty of piping production. If the welding process is not easy to occur flange deformation convex situation. When the ambient temperature is too low, the temperature difference between the welding zone and the non-welded area and the welding layer is caused by the uneven distribution of the flange stress. Take appropriate measures (such as induction heating, etc.) to ensure that the welding zone and non-welding range temperature difference is not between the thickness of the solder layer to maintain a temperature of not more than 200 ℃, can effectively solve the problem of flange deformation.
- After the pipeline welding to weld quality inspection. Check the project include: whether the cracks around the cracks, inclusions, stomata and excessive bite, splash and other phenomena, the weld is neat, with or without dislocation, whether the protruding inside and outside the surface, the outer surface in the process of damage or weaken Wall strength of the site and so on. For high pressure or ultrahigh pressure piping, the use of flaw detection to check the quality of welding is a common method. There are many methods of testing, commonly used x-ray detection, ultrasonic testing, etc., but have some limitations. For example, x-ray flaw detection for the diameter of less than 65a and wall thickness greater than 18mm of the weld can not be accurately determined, ultrasonic testing also has a similar problem, and ultrasonic testing can not quantify the defect of the weld. Using two kinds of testing methods combined, is conducive to check out the failure of welding.
The production process of the project is connected to the process by means of the cross-staggered process piping, and the supply of the customer gas is achieved by piping. A variety of pressure pipes and pressure vessels, design, manufacture, installation, operation, inspection, repair, transformation of any mistakes may lead to premature failure of the pipeline or an accident.
Pressure pipes are more prominent risk factors are over-temperature, overpressure, corrosion, wear and vibration. Overpressure overpressure is associated with malfunctions or abnormal overload of the main reaction vessel. Corrosion, wear and corrosion of the process material or impurity content and fluid velocity and so on. Vibration from the rotating machinery of the dynamic balance or poor design of the basic design does not meet the requirements, but more important is the pipeline fluid velocity is high, turning too much, cross-section changes in the formation of the exciting force pulsating. Corrosion, wear and tear gradually weaken the structural strength of pipes and fittings. Vibration can easily lead to loose connections and fatigue fracture of pipe connections. Even if it is a small pipeline pipe valve leakage or fracture will cause more serious disasters, such as space explosion, fire or poisoning. Years of practice has proved that: high-pressure process pipeline accident frequency and its harm as much as the pressure vessel accident.
Pressure vessels are mainly fixed pressure vessels such as various liquids, gas storage tanks, cylinders, dryers, adsorbers, condensers, separators, scrubbers and so on. The media in the pressure vessel is in a compressed state, and once the container explodes, the medium will produce a step-down expansion. The pressure generated by the pressure vessel explodes most of the shock waves, not only to destroy the entire equipment, but also damage the surrounding buildings and other facilities, and directly harm the personal safety of the surrounding people, causing casualties. The main causes of pressure vessel explosion are:
- Pressure vessel itself is flawed, such as container structure inside the crack, the container weld with Weld and missed welding phenomenon:
- Pressure vessel pressure over the design pressure, pressure gauge display distortion, safety valve calibration set the pressure is wrong or no normal take-off and so on;
- Pressure vessel corrosion is serious, pressure capacity decreased;
- Operational errors and so on.
Steel plate pile repeatedly used equipment, foundation or pier body to build out the water surface can pull out the steel sheet pile, remove the cofferdam. In order to make the work of pulling out the steel sheet pile can be carried out smoothly, the steel sheet pile and the underwater basement concrete contact parts can be coated with asphalt. In the removal of steel sheet pile before, to the cofferdam irrigation, so that the water inside the weir surface 1 ~ 1.5m. The use of hydrostatic pressure to push the steel sheet pile, so that the underwater cover of the concrete out. If necessary, piling hammers can be used to pull out the steel sheet pile, and then pull out the steel plate pile top should be prepared round hole, easy to connect from the hanging ring.
Pull out the steel sheet pile should be clean and clean, repair finishing, brushing anti-rust oil. Piling should be based on sheet type, length, respectively, number, registration, stacked neatly.
Hot-rolled structural pipe with continuous casting slab or raw rolling slab as raw material, heated by step heating furnace, high pressure water descaling into the rough rolling mill. The rough rolling material is cut into the tail and tail, then into the finishing mill, and the computer controlled rolling is carried out. After the finish rolling through laminar cooling and coiling machine to take a straight hair volume. Straight hair volume of the head and tail are often tongue-shaped and fish-like, thickness, width accuracy is poor, the edge often exist wave shape, folding, tower and other defects. Its weight heavier, coil diameter 760mm. Will straight hair volume by cutting head, cut tail, trimming and multi-pass straightening, leveling and other finishing line treatment, and then cut or re-roll (the general pipe industry like to use). That is: hot-rolled steel, flat hot-rolled coil, longitudinal cutting and other products. Hot rolled finishing volume if the pickling to remove the scale and oil after the hot rolling pickling plate. The product has a local alternative to the trend of cold-rolled structural pipe, affordable, well received by the majority of users.
Cold-drawn structural pipe with hot-rolled coil as raw material, pickling to remove the scale after the cold rolling, the finished product for the rolling hard roll. As a result of continuous cold deformation caused by cold hardening hard rolling strength, hardness, toughness index decreased, so the stamping performance will deteriorate, only for simple deformation of the parts. Rolling hard rolls can be used as raw materials for hot-dip galvanizing plants, since hot-dip galvanizing units are equipped with annealing lines. Rolling hard roll weight is generally 6 to 13.5 tons, coil diameter of 610mm.
General cold rolling plate, roll should be continuous annealing (CAPL unit) or hood furnace annealing to eliminate cold hardening and rolling stress, to meet the corresponding standard mechanical performance indicators.
The surface quality, appearance and dimensional accuracy of the cold-rolled structural pipe are better than those of the hot-rolled structural pipe, and the thickness of the product is about 0.18mm, so it is favored by the customers. To cold-rolled steel coil-based structure for the deep processing of products, a high value-added products. Such as electro-galvanized, hot-dip galvanized, fingerprint-resistant galvanized, color coated steel coil and vibration composite steel plate, PVC laminating steel plate, so that these products are beautiful, high corrosion resistance and other excellent quality, has been widely used. The cold rolled steel sheet must be finished after annealing, including cutting head, tail, trimming, leveling, leveling, rewinding, or slitting plate. Cold rolled products are widely used in automobile manufacturing, home appliances, instrument switches, construction, office furniture and other industries. The weight of each pack after the steel sheet is 3 to 5 tons. The flat weight is generally 3 to 10 tons / roll. Coil diameter 610mm.
The use and manufacture of fluid tubes
General boiler pipes are mainly used to make water wall tubes, boiling water pipes, superheated steam pipes, locomotive boilers with superheated steam pipes, large and small smoke pipe and arch brick.
High-pressure boiler pipes are mainly used to manufacture high-pressure and ultra-high pressure boiler superheater tube, reheater tube, air pipe, the main steam pipe.
However, the tube also has some limitations, such as in the plane under the conditions of bending, the tube is not as good as the square tube bending strength, some agricultural machinery skeleton, steel and wood furniture on the commonly used side, rectangular tube. According to different purposes also need to have other cross-shaped shaped steel pipe.
Seamless steel pipe for fluid delivery (GB / T8163-2008) is a general seamless steel pipe for conveying water, oil and gas.
Fluid tube manufacturing method
General use of the boiler pipes temperature below 450 ℃, domestic tube mainly with 10, 20 carbon steel hot-rolled tube or cold-drawn tube manufacturing.
High-pressure boiler pipes are often used in high temperature and high pressure conditions, the tube in the role of high temperature flue gas and water vapor, will be oxidized and corrosion. Requiring steel pipe with high durability, high oxidation resistance, and good organizational stability.
To determine the use of the track pile construction or crane crane construction, before the fight must be familiar with the underground geological and geography, the machine stopped at the place near the piling point, lateral construction, easy to observe the observation. Hang the vibration hammer, raise, straighten the tubing and cable;
Before the piling, the steel sheet pile by root inspection, remove the connection lock mouth corrosion, deformation of the steel sheet pile, unqualified to be trimmed before use; in the steel plate pile lock grease to facilitate the pull out;
Hammer down, open the hydraulic mouth, pull a steel sheet pile to the piling hammer, the lock port to put the oil, from the hammer; so that the steel sheet pile to the folder, the hydraulic press, clamping steel sheet pile. Rising hammer and pile, to the piling location; alignment pile and positioning pile lock mouth, hammer down, by hammer and pile weight pile to the soil below a certain depth can not fall;
Try to piling hammer for 30 seconds or so, stop the vibration, the use of hammer inertia piling to a solid soil, start the vibration hammer piling down, control piling hammer down the speed, as far as possible to keep the pile vertical, so that the mouth can be successfully bite. In the plug process at any time to monitor the monitoring of each pile of the slope of not more than 2%, when the skew is too large can not be used Lazhi method of adjustment, pull up;
Plate pile to the design height before the stop vibration, vibration hammer for inertia continue to turn a certain time, piling to the design height;
Release the hydraulic clamp, hammer up, hit the second pile, the above class pushed to finish all the piles.