Flanges that are connected to vessels or pipes by fillet welding are referred to as having a "flat welding" connection. Any flange will do in this situation. When designing the component, it is important to determine whether the integral flange or the loose flange should be used based on the degree of integrity of the flange ring and the straight cylinder section. The neck and non-neck variations of the ring that makes up the flat welding flange are both available. In comparison to the neck butt welding flange, the flat welding flange has a more straightforward construction and uses less material. However, the flat welding flange's rigidity and sealing performance are not nearly as good as those of the neck butt welding flange. Flanges that are flat and welded are frequently utilized in the process of connecting pipelines and vessels that operate at medium or low pressure.
A flat welding flange not only reduces the amount of space and weight required for the joint, but it also guarantees that the joint will not leak and will have excellent sealing performance. As a result of the decrease in the diameter of the seal, the size of the compact flange has also shrunk, which has the effect of reducing the cross-section of the sealing face. Second, a sealing ring has been installed in place of the flange gasket so that the sealing surface can be made to correspond exactly with the sealing surface. When done in this manner, only a modest amount of pressure is necessary to achieve the desired degree of compression in the cap. As the required pressure drops, the size of the bolts and the total number of bolts can be decreased proportionately. As a result, a new type of flat welding flange that is both compact and lightweight has been designed. Because of this, the flat welding flange type is a type of flange product that is of a relatively high quality, which reduces mass and space, and plays an important role in industrial applications.
The principle behind the seal created by the flat welding flange is as follows: the two sealing surfaces of the bolt compress the flange gasket in order to create a seal; however, this also causes the seal to become compromised. In order to keep the seal intact, it is necessary to keep the bolt force at a very high level. As a result, the bolts need to be redesigned to have a larger diameter. Because larger nuts must be mated with larger bolts, nuts with larger diameters must be used with bolts that have a larger diameter. This makes it impossible to tighten the nuts. However, the bendable flanges that can be used increase in number in proportion to the larger the diameter of the bolts.
Increasing the wall thickness of the flange portion is the method that will be used. The entire device will require enormous size and weight, which becomes a particular problem in the offshore environment. In this environment, the weight of the flat weld flange is always the main concern one needs to pay attention to, so the size and weight of the entire device will be a particular issue.
Methods of Polishing for Flanges Made of Duplex Steel
Methods of Polishing for Flanges Made of Duplex Steel.
1. Polishing techniques for dual-phase steel flanges include hand-polishing, mechanical polishing, chemical polishing, and electrochemical polishing. Polishing the flange can improve its resistance to corrosion as well as its appearance by making it more decorative. Phosphoric acid and chromic anhydride are still utilized in the process of electropolishing stainless steel in its current iteration. The polishing and cleaning process will result in the discharge of some chromium and phosphorus into the waste water. contamination of the natural environment.
2. On the surface of the dual-phase steel flange, a passive film will form, and the oxide film will start to dissolve. Both of these processes will take place simultaneously. Because of the microscopically inconsistent surface of the dual-phase steel flange, the microconvex part on the Pipe Flange surface dissolves preferentially, and the rate of dissolution will be higher than that of the concave part. The film disintegrates and forms almost simultaneously, but the rates at which these processes occur are not the same. As a consequence of this, the roughness of the surface of the duplex steel flange is smoothed out, resulting in a surface that is glossy and smooth.
3. Polishing can fill some surface defects, such as surface pores and scratches, to improve fatigue resistance and related corrosion resistance. This is accomplished by filling surface pores and scratches. It has sufficient plasticity and toughness for this forming, as well as excellent resistance to stress corrosion cracking, particularly in environments rich in chloride ions. The yield strength of duplex steel flanges is more than double that of austenitic stainless steel.
What factors contribute to flanges developing leaks?
What factors contribute to flanges developing leaks?.
1. Because the pipe and the flange are both vertical, but the two flanges are not concentric, and because the flanges themselves are not concentric, the surrounding bolts are unable to freely penetrate the bolt holes, this condition is referred to as "wrong mouth, wrong seam. "There is no other method; the only options are to use reaming or to screw small bolts into the bolt holes. This will result in a reduction in the tension between the two flanges, and it will also cause the sealing surface of the sealing surface to become deviated, making it much more likely that there will be a leak.
2. The gasket undergoes chemical changes, the corrosive medium penetrates into the gasket, the gasket begins to soften, loses compressive force, and causes flange leakage as a result of the corrosion effect. The corrosion effect occurs as a result of the gasket being corroded by a corrosive medium for a long period of time.
3. The fact that the pipeline and the flange are not perpendicular to one another, that they are not concentric, and that the surface of the flange is not parallel is referred to as eccentricity and eccentricity, respectively. Flange leakage will take place whenever the load pressure of the gasket is exceeded by the pressure of the internal medium. This issue is typically brought on by improper installation or maintenance, and the solution is not too difficult to locate. As long as the actual inspection is carried out, stainless steel flange there is no need to worry about the accident happening.
4, the opening, or the gap between the flanges, is excessively large. When the flange clearance is too large, causing external loads (such as axial loads or bending loads), the gasket will be impacted or vibrated, lose the compression force, and gradually lose the kinetic energy of the seal, which will ultimately result in failure. This can be avoided by keeping the flange clearance as small as possible.
5. When installing flanges, the butt joint of two adjacent flanges is the preferred method due to the pressure involved. The temperature of the pipeline will change after it enters the medium, which will cause the pipeline to expand or deform. As a result, the flange will be subjected to bending load or shear force, which will easily lead to the failure of the gasket. Nevertheless, this will occur during the production of the system.
6. The term "wrong hole" refers to the situation in which the pipe and the flange are concentrically aligned, but the gap between the two bolts is larger than the bolt hole. The incorrect hole will cause the bolt to become stressed, and since the force cannot be eliminated, shear force will be produced on the bolt. This will cause the bolt to break for an extended period of time, which will lead to the failure of the seal. The thermal expansion and contraction of the fluid medium, as well as the expansion or contraction of the bolt, will cause the gasket to have a gap, which will allow the medium to leak through the pressure. This is caused by the fluid medium's thermal expansion and contraction.
