What are the connection methods of stainless steel water pipes, and which connection method is more reliable?
Let's compare several common connection methods:
1. Flexible connection
Principle: Insert the pipe into the nozzle of the pipe fitting, tighten the cap nut with a special wrench, and seal the sealing ring through the compression ring to complete the connection.
Features: Easy to install, detachable, able to adapt to the harsh environment such as foundation sinking.
Scope of application: Below DN60, indoor exposed installation, underground buried pipes, earthquake subsidence, and the environment where heavy vehicles pass.
Note: It is necessary to roll grooves on the pipe end with a grooving machine on site to fix the C-groove.
Step 2 compress the connection
Principle: Insert the pipe into the nozzle of the pipe fitting, fasten it with nuts, and press the sleeve at the nozzle with spiral force through the sealing ring to seal it, thus completing the connection.
Features: quick installation and disassembly, but the connection reliability is relatively weak, and the thread is easy to loosen when shaking, which leads to the decrease of the compression force of the nut on the seal and water leakage; The pipe fittings are complicated in structure and high in cost; Can't be buried in the dark.
Scope of application: used for temporary pipelines with a diameter of not more than 50 and not buried underground.
3. Welding joint
(1) welded connection?
Principle: Slot the pipe end and weld the pipe manually or automatically.
Features: The traditional connection method has high welding strength, but it has on-site requirements for welding conditions.
Scope of application: large and small pipe diameters can be used, and it can be installed openly or buried underground.
Note: The wall thickness of the pipeline is required to be thick, and the on-site welding has high technical requirements for the installers, so it cannot be treated by solid solution, and the welding quality cannot be guaranteed.
(2) Butt argon arc welding connection (3) Socket argon arc welding connection
Principle: Insert the pipe into the socket pipe fitting, and the pipe fitting and the pipe are welded by annular argon arc welding, which plays a sealing role and completes the connection.
Features: reliable connection, simple pipe structure, but difficult operation and high cost; Require strong heat source and live working, which has fire safety hazards; It is difficult to protect the inner wall of stainless steel during field operation, which leads to the oxidation of the inner wall of stainless steel, and the oxidation layer can not be removed after welding, which is easy to rust.
Scope of application: large and small pipe diameters can be used, and it can be installed openly or buried underground.
Description: In-situ welding can't carry out solution heat treatment, and the corrosion resistance of the weld is the same as that of carbon steel, so intergranular corrosion and stress corrosion will occur, which will affect the service life.
4 Flange connection
(1) flange connection
Principle: Flanges and pipelines are welded by annular argon arc welding, and fastened by quick clamps or bolts, so that the gasket between flanges plays a sealing role and the connection is completed.
(2) Groove connection
Principle: Also called clamp connection. When connecting, firstly, an annular groove is machined at the joint between the pipe fitting and the flat end of the pipeline, and then the connection mode of quick assembly joint consisting of appropriate clamps, C-shaped rubber sealing rings and fasteners is adopted.
Features: the traditional flange welding method can also be transformed into a flexible flange, with a flange or welding ring at the end of the pipe and a rubber seal in the groove, which protects the seal by limiting compression.
Scope of application: It is mainly used for large-diameter pipelines with a diameter greater than or equal to 100.
5. Clamping connection
(1) Single clamping pressure
Principle: Insert the pipe into the pipe fitting, with protruding U-shaped grooves at both ends of the pipe fitting, built-in sealing rings, and connect them with the socket parts of special pipe fitting tools.
(2) Double clamping
Principle: Improved S-shaped crimping technology based on single crimping technology.
Features: simple and quick installation, reliable sealing, vibration resistance, avoiding the possibility of loose union, short installation period and low cost. Single-card O-ring is a hexagonal locking structure, and the double-card type has an extended edge at the port compared with the single-card type.
Scope of application: It is used to connect various pipes with a diameter not greater than DN 100.
Note: The workload of press-fitting connection construction site is small, only pipe cutting, deburring, intubation positioning and press-fitting are needed, and no other treatment is needed to avoid quality defects caused by ideological factors. The O-ring in the pipe fitting has certain elasticity after compression, and it will automatically compensate after thermal expansion and cold contraction to ensure the safety of the pipeline. Card connection has become the main connection mode of stainless steel pipes with diameter less than or equal to 100mm, and it also occupies most market share.
6. Double-ring compression connection
The "double-ring crimping" mode of stainless steel water pipe is a national patent product and a new connection mode. It is a re-optimized structure on the basis of annular pressure pipe fittings, and the size of the sealing sleeve is increased. On the basis of the original annular pressure, two sealing surfaces are added, with a total of ***4 sealing surfaces, so as to avoid the phenomenon of empty drum in the sealing section, improve the sealing performance and prevent leakage.
In the process of pressing with special tools, the tools are evenly pressed inward along the outer edge of the sealing section of stainless steel water pipes, and the scientific compression ratio is calculated according to the thickness of different rubber sealing rings, that is, sealing bags, so that the products can be molded at one time, with high tensile strength and good sealing performance, and the products are more scientific, firm and durable.
At present, the double-ring crimping method is rare in the market because of its unique advantages. I know a ring pressure connection manufacturer in Liangping, Chongqing, whose name is Chongqing Juyuan Stainless Steel. They do ring pressure connection, not bad!