Instruments and Meters: [Question of the Week] Week 42, 2011: What precautions should be taken when installing flanges?

This post was last edited by denghl on 2012-12-12 at 21:11. 1. The flange must have sufficient strength; it must not deform during fastening. The flange sealing surface should be flat and clean; during installation, oil stains and rust spots must be carefully removed. 2. The gasket should have good oil resistance and aging resistance, as well as decent elasticity and mechanical strength. During installation, gaskets of different cross-sections and sizes should be selected based on the shape of the joint, and they must be placed correctly. 3. The tightening force of the flanges should be uniform, and the compression amount of the gasket should be controlled at around 1/3.

This post was last edited by denghl on 2012-12-12 at 21:12. 1 Before installing the flange, it is necessary to ensure that it meets the design requirements and relevant standards. 2 When handling and installing flanges, be careful to avoid accidents caused by bumps or scratches. 3 Before installation, the inside of the pipes must be cleaned to remove impurities such as iron shavings. 6 The flange surface shall be free from damage, scratches, etc., and kept clean. In particular, when using metal gaskets (with oval or octagonal cross-sections), the grooves on the flange must match the gasket. Red lead should be applied for mating to ensure a proper seal. The perpendicularity of the flange surface on the pipe to the pipe’s centerline, as well as the tolerances of the flange bolt holes, must be within the allowable values. The valve and piping centerlines must be aligned before installation. When connecting two flanges, it is first necessary to press the flange sealing surfaces and the gasket evenly together, thereby ensuring that the flanges are joined under equal bolt stress. When tightening bolts, use a wrench that matches the nut. When using hydraulic or pneumatic tools for tightening, be careful not to exceed the specified torque. When tightening the flange, avoid uneven force; it should be tightened in a symmetrical, alternating sequence. After installing the flange, verify that all bolts and nuts are tightened evenly. The material of bolts and nuts must meet the specified requirements. After tightening, the bolt head should protrude from the nut by about two pitches. When tightening bolts and screws, washers should be used to prevent loosening due to vibration. To prevent sticking between the threads at high temperatures, an anti-adhesive (molybdenum disulfide) should be applied to the threaded areas during installation. Used for high-temperature valves operating at temperatures above 300 degrees Celsius; after the temperature rises, it is necessary to retighten the flange connection bolts, the valve cover fastening bolts, the pressure seal bolts, and the gasket compression bolt. Valves for low temperatures are installed at atmospheric temperature. In practical applications, when the medium passes through, a low-temperature state is created. Due to the temperature difference, components such as flanges, gaskets, bolts, and nuts contract. Moreover, since the materials of these components vary, their linear expansion coefficients also differ, creating conditions that make leakage very likely. Based on this objective reality, when tightening bolts at atmospheric temperature, a torque that takes into account the shrinkage of various components at low temperatures must be used. 7 Installation of valves connected by welding (1) The socket and spigot for socket welding, as well as the groove for butt welding, must be prepared correctly in accordance with the relevant standard specifications. (2) During welding, it is necessary to prevent iron shavings and weld spatter from entering the pipes; tungsten inert gas welding should be used. (3) During welding, the valve should be in a slightly open position. (4) The welding material should be selected appropriately based on the valve and piping materials. When using coated welding electrodes, it is necessary to check how they are stored and to confirm that the appropriate drying treatment has been applied according to the type of coated welding electrode. (5) Personnel engaged in welding operations must meet the requirements for welding technicians. (6) In cases where heat treatment is required after welding, it is necessary to check the records of the heat treatment time and temperature profile. (7) The welded areas shall be visually inspected or subjected to non-destructive testing to ensure that there are no harmful defects such as cracks, weld beads, or undercut

This post was last edited by denghl on 2012-12-12 at 21:12. 1. The flange must have sufficient strength; it must not deform during fastening. The flange sealing surface should be flat and clean; during installation, oil stains and rust spots must be carefully removed. 2. The gasket should have good oil resistance and aging resistance, as well as decent elasticity and mechanical strength. During installation, gaskets of different cross-sections and sizes should be selected based on the shape of the joint, and they must be placed correctly. 3. The tightening force of the flanges should be uniform, and the compression amount of the gasket should be controlled at around 1/3. Reply 1# Baghdad

This post was last edited by denghl on 2012-12-12 at 21:12. 1) Do not forget to install gaskets between the two mating flanges, and the choice of gaskets must be made in accordance with the design requirements; they cannot be selected arbitrarily. The gasket must be installed on the inside of the bolt; the higher the pipeline pressure, the narrower the gasket should be. 2) The bolts to be used must be selected according to the specifications specified in the design; they cannot be replaced arbitrarily. The nut and bolt heads should be supported vertically on the flange surface. 3) When tightening the nuts, use a diagonal tightening method; otherwise, it is easy to cause tilting and lead to leaks. The sequence for tightening the nuts is shown in the figure.

This post was last edited by denghl on 2012-12-12 at 21:12. 1. Check whether the nominal diameter and pressure of the flange are compatible； 2. When installing the flange, apply rust preventive grease to the pipe end and the gasket before placing it (except for degreased pipes), and the gasket should be positioned accurately on the sealing surface. 3. After the flange bolts are tightened, the threads exposed outside the nuts should be no less than three turns, and the exposed threads at both ends of each bolt should be roughly the same.

This post was last edited by denghl on 2012-12-12 at 21:12. 1 Check whether the inner surface of the flange is smooth, whether there are any foreign objects, burrs, or deformations； 2. Use bolts that are as compatible as possible with the flanges, ensuring that the direction of the bolts and nuts is consistent ； Place the 3 pads level with each other, trying to align their centers with the center of the flange ； 4. When tightening bolts and nuts, apply force evenly and symmetrically in a diagonal pattern ； 5 Install the grounding wire between the two flanges.

This post was last edited by denghl on 2012-12-12 at 21:12: 1. Coordinate well with the layout of instrument components; 2. Prevent leaks

There’s nothing special to note; the flange model is the same. The flange just needs to be installed horizontally and tightened properly, and that’s it.

Size, dimensions, material, pressure rating, characteristics of the medium

Hehe. Before installing the valve, it’s necessary to ensure that it meets the design requirements and relevant standards. 2 When handling and installing valves, be careful to avoid accidents caused by bumps or scratches. 3 Before installation, the inside of the pipes should be cleaned to remove impurities such as iron shavings, so as to prevent foreign objects from getting trapped in the valve seals. Additionally, the valve should be in a closed position during installation. 4 During valve lifting operations. The valve must be lifted properly at the designated lifting position; it shall not be lifted or pulled under conditions where only partial forces are applied to it. 5 When installing the valve, ensure that the flow direction of the medium, the installation method, and the position of the handwheel comply with the regulations. 6 Installation of flanged connection valves. The flange surfaces of valves and piping should be free from damage, scratches, etc., and kept clean. In particular, when using metal gaskets (with oval or octagonal cross-sections), the grooves on the flange must match the gasket. Red lead should be applied for mating to ensure a proper seal. The perpendicularity of the flange surface on the pipe to the pipe’s centerline, as well as the tolerances of the flange bolt holes, must be within the allowable values. The valve and piping centerlines must be aligned before installation. When connecting two flanges, it is first necessary to press the flange sealing surfaces and the gasket evenly together, thereby ensuring that the flanges are joined under equal bolt stress. When tightening bolts, use a wrench that matches the nut. When using hydraulic or pneumatic tools for tightening, be careful not to exceed the specified torque. When tightening the flange, avoid uneven force; it should be tightened in a symmetrical, alternating sequence. After installing the flange, verify that all bolts and nuts are tightened evenly. The material of bolts and nuts must meet the specified requirements. After tightening, the bolt head should protrude from the nut by about two pitches. When tightening bolts and screws, washers should be used to prevent loosening due to vibration. To prevent sticking between the threads at high temperatures, an anti-adhesive (molybdenum disulfide) should be applied to the threaded areas during installation. Used for high-temperature valves operating at temperatures above 300 degrees Celsius; after the temperature rises, it is necessary to retighten the flange connection bolts, the valve cover fastening bolts, the pressure seal bolts, and the gasket compression bolt. Valves for low temperatures are installed at atmospheric temperature. In practical applications, when the medium passes through, a low-temperature state is created. Due to the temperature difference, components such as flanges, gaskets, bolts, and nuts contract. Moreover, since the materials of these components vary, their linear expansion coefficients also differ, creating conditions that make leakage very likely. Based on this objective reality, when tightening bolts at atmospheric temperature, a torque that takes into account the shrinkage of various components at low temperatures must be used. 7 Installation of valves connected by welding (1) The socket and spigot for socket welding, as well as the groove for butt welding, must be prepared correctly in accordance with the relevant standard specifications. (2) During welding, it is necessary to prevent iron shavings and weld spatter from entering the pipes; tungsten inert gas welding should be used. (3) During welding, the valve should be in a slightly open position. (4) The welding material should be selected appropriately based on the valve and piping materials. When using coated welding electrodes, it is necessary to check how they are stored and to confirm that the appropriate drying treatment has been applied according to the type of coated welding electrode. (5) Personnel engaged in welding operations must meet the requirements for welding technicians. (6) In cases where heat treatment is required after welding, it is necessary to check the records of the heat treatment time and temperature profile. (7) The welded areas shall be visually inspected or subjected to non-destructive testing to ensure that there are no harmful defects such as cracks, weld beads, or undercut