The high pressure elbow is a kind of pipe fitting which is used to turn the high pressure pipe at different angles. The proportion of all pipe fittings used in the high-pressure pipeline system is about 80%. The wall thickness of general high pressure elbow is thicker than that of common elbow, or the strength of high pressure resistance of material is higher than that of common elbow. There are three ways of butt welding, socket welding and thread connection.
High pressure elbow technology：
The productionofhigh pressure elbow has special hydraulic machine cold push system, if heating push system, hydraulic machine high pressure pressure molding production elbow production process comparison.
1. The production process of carbon steel elbow by intermediate frequency heating is as follows: pipe blank sawing cutting, installation of multiple parts, continuous production by intermediate frequency heating,finishing of semi-finished oil press, turning and cutting of elbow groove. This method has the advantages of high production rate, small amount of polishing work, general labor intensity of workers, low material loss, small machining allowance of elbow, low production cost, general product quality, simple shape of material, but heating and correction.
2. The production process of elbow by hydraulic press is as follows: saw cutting of multi-piece pipe billet (the shape of the pipe billet is trapezoid), heating by human oil furnace, twice pressing by hydraulic press, shaping, twice round checking by firework, manual polishing and turning cutting processing port. This kind of elbow production process method is multifangled, the production rate is not high, the polishing work is big, the material loss is big, the production cost is also high.
3. The process of producing carbon steel and stainless steel high-pressure elbow by cold pushing with special hydraulic press for elbow is as follows: saw cutting off the blanks of multiple pipe blanks (the shape of the blanks of the blanks is trapezoid), mass production by cold pushing, turning and cutting the elbow groove. This pushing production method is characterized by simple working procedure, high production rate, low cost, high product accuracy, small grinding workload, low labor intensity, low material loss and small machining allowance for elbow. Product quality is good, but the shape of the opening complex.
High pressure elbow advantage
1.High pressure elbow has good compression resistance, and other excellent characteristics are required in different pipelines and systems. For example, in the concrete conveying pipeline, the high pressure elbow in the mud conveying pipeline should not only be able to withstand higher pipeline pressure, but also have good wear resistance.
2. Corrosion resistance and acid and alkali resistance. It is often used in chemical raw material conveying pipeline system.High pressure elbow high pressure resistance is generally applicable to petroleum, gas, aerospace, Marine, chemical, hydropower, fire, construction and boiler and other industries pipeline series.
Weldingofhigh pressure elbow:
1. In order to prevent intergranular corrosion caused by heating, the welding current should not be too large, about 20% less than the carbon steel electrode, the arc should not be too long, quick cooling between layers, and narrow welding pass is advisable.
2. High pressure elbow electrode should be kept dry, when using titanium calcium type should be 1 hour after 150 ℃ drying, low hydrogen type should be 1 hour after the 200-250 ℃ drying (can't repeat drying, otherwise coated easy cracking flake), to prevent the covering viscous oil and other dirt, lest cause weld increased carbon content and affects the quality of weldment.
3.Duringhigh pressure elbow welding, carbides are separated out by repeated heating, which reduces the corrosion resistance and mechanical properties.
4. Thehigh pressure elbow has a large hardening after welding, which is easy to generate cracks. If the use of the same type high pressure elbow welding, above 300 ℃ preheat and 700 ℃ or so slow cooling after welding. If the welding parts can not be post-welding heat treatment, the selection of high pressure elbow welding rod.