Stainless steel pipes are widely used in industrial pipeline systems, especially in the fields of chemical, petroleum, natural gas, pharmaceuticals, etc. In order to ensure the sealing, stability and maintainability of the pipeline system, the connection method between stainless steel pipes and other pipe fittings is particularly important. Among the many connection methods, flange connection has become the most commonly used one due to its reliability, convenience and detachability. This article will introduce in detail How to flange out a stainless steel pipe, including the basic concept of flange connection, selection of flange type, operation steps and precautions of flange connection.
Basic concept of flange connection
Flange connection refers to a way of connecting stainless steel pipes to other parts of the pipeline system through components such as flanges, bolts and sealing gaskets. The flange itself is usually a circular metal ring with multiple holes for bolt connection. The advantages of flange connection include easy disassembly and maintenance, good sealing, and suitable for harsh environments such as high pressure, high temperature and strong corrosion.
The flange connection of stainless steel pipes mainly relies on the sealing effect of the flange. Usually, a sealing gasket (such as asbestos gasket, metal gasket, etc.) is placed between the two flanges, and the two flanges are pressed together by bolts to form a sealed connection.
Selection of flange type
There are many different flange types for stainless steel pipe flange connection, the most common ones are as follows:
1. Flat welding flange
The flat welding flange is the most common flange type, suitable for the connection of medium and low pressure pipelines. The sealing surface of its flange is relatively flat, suitable for parallel connection with the welding port of the pipeline.
2. Butt welding flange
Butt welding flange is usually used for the connection of high pressure and large diameter pipelines, especially in situations where it needs to withstand high pressure or temperature. This type of flange requires the flange plate to be butt welded to the pipeline, and its structure is relatively strong and suitable for most working conditions.
3. Loose flange
Loose flange is mainly used in situations where the pipeline needs to be frequently disassembled or inspected. Compared with ordinary flanges, the loose flange design is simpler and easy to disassemble.
4. Raised flange
Raised flange is often used in situations where high-strength sealing and high pressure are required. Its flange surface is convex, which can better ensure the sealing effect.
5. Blank flange
Blind flange is used to close the opening of pipelines or equipment, usually at the end of the pipeline to prevent pipeline fluid leakage.
When choosing the right flange type, it is necessary to comprehensively consider factors such as the pipeline’s pressure level, temperature, fluid type, working environment, etc. For stainless steel pipes, flange materials with good corrosion resistance and suitable for the required working conditions should be selected.
Operation steps of flange connection
For the flange connection of stainless steel pipe, the specific operation steps are as follows:
1. Preparation
Before starting the connection, you need to prepare the following tools and materials:
Stainless steel flange (suitable for pipe specifications)
Sealing gasket (select the appropriate type according to the medium and pressure)
Bolts and nuts
Tools such as wrenches and torque wrenches
Pipe cutters (if the pipe needs to be cut)
Pipe cleaners or cleaning cloths
2. Pipe preparation
Before making flange connections, you need to ensure that the pipe end is flat, clean and free of debris. If there are burrs or unevenness on the pipe end face, it should be cleaned and processed first. For stainless steel pipes, you can use a pipe cutter to cut to the appropriate length and ensure that the cut surface is flat.
3. Installation of flange
Place the flange on the pipe end and ensure that the sealing surface of the flange is well connected with the pipe end face. There is no need to tighten the bolts too much at this time. Make sure that the holes of the flange are aligned to facilitate the next step.
4. Installation of sealing gasket
Place the sealing gasket between the two flanges. Choose the appropriate type of sealing gasket according to actual needs, such as metal gasket, asbestos gasket, polytetrafluoroethylene gasket, etc. The gasket should ensure that it covers the entire sealing surface and avoids deviation or wrinkles.
5. Bolt fixing
Insert the bolts through the holes of the flange and fix them with nuts. It is not necessary to tighten them completely at this time, just screw the bolts into the flange and keep them loose.
6. Symmetrical tightening
Use a torque wrench to gradually tighten the bolts in a symmetrical order. First, tighten all the bolts lightly, and then gradually tighten them according to a certain torque value to ensure that both sides of the flange are evenly stressed and the sealing gasket can be evenly compressed to achieve the ideal sealing effect. Pay special attention not to over-tighten to avoid damaging the sealing gasket or flange.
7. Inspection and testing
After tightening, check whether the bolts are tightened in place and ensure that the flange connection is firm. A pressure test can be performed to check whether there is leakage at the pipe connection. If leakage is found, it should be disassembled and checked in time, and the sealing gasket should be readjusted or replaced.
Notes
1. Flange material selection: When selecting stainless steel flanges, appropriate materials should be selected according to the medium, pressure, temperature and other conditions of the pipeline, such as stainless steel 304, 316, 304L, etc.
2. Selection of sealing gaskets: The selection of sealing gaskets should be based on the properties of the pipeline fluid (such as corrosiveness, temperature, etc.) to ensure that the sealing effect can be effectively guaranteed.
3. Control of tightening torque: Over-tightening will cause flange deformation or damage to the sealing gasket, and too loose will easily leak. Tighten according to the torque required by the design.
4. Regular inspection and maintenance: Once the flange connection is completed and put into use, it still needs regular inspection and maintenance, especially under high temperature and high pressure conditions, pay attention to the sealing of the flange connection and the looseness of the bolts.
Flange connection of stainless steel pipes is a simple and reliable connection method, which is widely used in various industrial pipeline systems. Through correct flange selection, operation steps and sealing treatment, the stability and safety of pipeline connection can be ensured. Mastering the essentials of flange connection, especially during pipeline installation and maintenance, can effectively improve the reliability and service life of the system.
