1.The welding rod shall be kept dry during use. The calcium titanate type shall be dried at 150′C for 1 hour, and the low-a hydrogen type shall be dried at 200-250 ℃ for 1 hour (the drying shall not be repeated for many times, otherwise the skin is easy to crack and peel off) to prevent the welding rod skin, sticky oil and other dirt, so as to avoid increasing the carbon content of the weld and affecting the quality of the weldment.
2.During welding of stainless steel flange pipe fittings, carbides are precipitated by repeated heating, which reduces corrosion and mechanical properties.
3.The hardened American standard flange of chrome stainless steel flange pipe fittings after welding is large and easy to crack. If the same type of chromium stainless steel electrode (G202, G207) is used for welding, preheating above 300 ℃ and slow cooling treatment around 700 ℃ after welding are required. If the weldment cannot be subject to post-weld heat treatment, stainless steel flange pipe electrode (A107, A207) shall be selected.
4.For stainless steel flange, proper amount of stability elements such as Ti, Nb and Mo are added to improve the corrosion resistance and weldability. The weldability is better than that of chrome stainless steel flange. When the same type of chrome stainless steel flange welding rod (G302, G307) is used, preheating above 200 ℃ and tempering around 800 ℃ after welding shall be carried out. If the weldment cannot be heat treated, stainless steel flange pipe electrode (A107, A207) shall be selected.
5.Stainless steel flange pipe fittings and butt-welding flange welding rods have good corrosion resistance and chemical resistance, and are widely used in chemical, fertilizer, petroleum and machinery manufacturing.
6.In order to prevent eye-to-eye corrosion caused by the heating of the flange cover, the welding current should not be too large, about 20% less than that of the carbon steel electrode, the arc should not be too long, and the inter-layer cooling should not be slow, and the narrow weld bead should be preferred.
The carbon steel flange is used in a special way, so it requires smooth, tensile, compressive, torsional and other characteristics of materials. It can be used under high pressure without distortion. Because carbon steel has few burrs, its friction force is also very small, and it can be more used in equipment.
In addition, carbon steel flanges should be manufactured in strict accordance with China’s or relevant industry standards. Never use unqualified materials to make them. The more you can’t cut corners on the size, these opportunistic ways will lead to inferior and unqualified products, which will cause failure to the entire French system, even cause economic loss of property and casualties and other stable accidents.
Anyone who has heard of carbon steel flange knows that its material casting is very complex. In terms of its material, carbon steel is also different from some other steels, and its performance is better than that of steel. So a good flange is mostly made of carbon steel, that is, the so-called carbon steel flange. In addition to carbon, carbon steel generally contains a small amount of silicon, manganese, sulfur, phosphorus and other substances, so it has its particularity in material.
The measurement method of carbon steel flange and the preparation work before measurement will be briefly introduced by the editor.
1.During the measurement, three people should be arranged, two of them are measuring, one is checking and filling in the form. If there is no condition to use the external caliper and steel ruler, the caliper can be used as the measuring tool. Measurement is a meticulous work and a prerequisite for fixture installation. The measurement and record shall be prepared correctly, and the form shall be filled in carefully and clearly. In the actual measurement work. To cooperate with each other, we should be able to cooperate and use in accordance with the correct principles.
2.According to the position of the large flange before measurement, the connection diagram and number of the large flange of the equipment should be drawn at first, so that the fixture can be installed according to the corresponding methods and principles, and the normal use can be determined.
3.Because the outer diameter of the carbon steel flange may be different, the wrong hole (different center) and the thickness of the gasket are different, the processed fixture should not be interchanged with the side carbon steel flange, so measuring the size and quantity of each part is the key. Ixtere processing and installation.
Carbon steel flanges are widely used in daily applications, and the consumption is not slow. Therefore, the regular maintenance of carbon steel flanges needs to have corresponding rules to maintain the quality of carbon steel flanges as much as possible and improve the working speed. Here we share with you the stable performance of stainless steel and carbon steel flanges and what maintenance needs to be done:
1.When the carbon steel flange is closed, there is still some medium left in the valve body, and it also bears the specified pressure. Before overhauling the carbon steel flange, close the shut-off valve in front of the carbon steel flange, open the carbon steel flange to be overhauled, and completely release the internal pressure of the valve body. In case of electric carbon steel flange or pneumatic ball valve, the power and air supply should be disconnected at first.
2.Generally, the soft sealing carbon steel flange uses tetrafluoroethylene (PTFE) as the sealing material, and the sealing surface of the hard sealing ball valve is made of metal surfacing. If it is necessary to clean the pipe ball valve, care should be taken to prevent leakage due to damage to the sealing ring during disassembly.
3.When disassembling the carbon steel flange, the bolts and nuts on the flange should be fixed first, and then all the nuts should be tightened slightly and firmly fixed. If individual nuts are fixed properly before other nuts are fixed, the gasket surface will be damaged or cracked due to uneven loading between flange faces, resulting in medium leakage from valve flange butt joint.
4.If the valve is cleaned, the solvent used shall not conflict with the parts to be cleaned and shall not corrode. If it is carbon steel flange for gas, it can be cleaned with gasoline. Other parts can be cleaned with reclaimed water. During cleaning, the residual dust, oil and other attachments shall be completely cleaned. If they cannot be cleaned with clean water, they can be cleaned with alcohol and other cleaning agents without damaging the valve body and parts. After cleaning, wait for the cleaning agent to volatilize before assembly.
5.If slight leakage is found at the packing during use, the valve rod nut can be slightly tightened until the leakage stops. Do not continue to tighten.
6.Before use, the pipeline and the overflow part of the valve body shall be cleaned with water to prevent residual iron filings and other sundries from entering the inner cavity of the valve body.
In addition, if the carbon steel flange is placed outdoors for a long time, and there are no measures to be afraid of water, it will lead to corrosion of some valve bodies and components. In this way, it is necessary to test the stability of carbon steel flange during use.
Post time: Feb-07-2023
