1. Mutual learning of domestic and foreign stainless steel pipe standards. The internationally common stainless steel pipe connection methods mainly include compression type (convex type), pressing type, push type, welding type (socket argon arc welding type and butt welding type), etc., such as the compression type and welding type pipe wall thickness is based on the British BS4127 and EU DIN EN10312 standards, and the compression type (pressing type) adopts the Japanese JWWA G116 standard. Therefore, the domestic “Wall Stainless Steel Water Pipe” standard, the wall thickness, and other indicators of stainless steel pipes are consistent with the British, EU, ISO, and Japanese standards according to different connection methods.
2. Comparison and analysis of several connection methods
Preface 1. Features of convex type:
It is easy to install, and the connection is not deformed inside or outside. It is a loose connection and is easy to maintain. Scope of application: cold water system, pipeline direct drinking water system, water treatment equipment system. Surface installation is more suitable, mainly considering the future replacement of the sealing ring, and the use of hot water systems should be avoided as much as possible. The advantage of this type of connection is that it is simple to install, convenient, and easy to maintain. When the sealing ring in the pipe ages, it is relatively simple and convenient to replace. You only need to unscrew the nut to replace it. The disadvantage is that it is suitable for only one occasion, the aging of the sealing rings in hot water systems is more prominent, and the cost is higher. Concealed pipes and hot water systems are generally not recommended.
Preface 2. Features of compression type:
Easy to install, the external pipe and internal rubber ring at the joint are evenly pressured into a hexagonal shape. Scope of application: cold water system, piped direct drinking water system, and surface-mounted pipes are more suitable. The advantages are simple and convenient connections, short working hours, and moderate cost. The disadvantage is that it is suitable for only one occasion and is troublesome to maintain. It is troublesome to replace the sealing ring in the pipe when it ages. Since it has been stuck during the connection, it is necessary to sew off both ends of the pipe before replacing it. The hot water system should also be avoided as much as possible, mainly because the service life of the sealing ring is uncertain in the hot water system. Therefore, concealed pipes and hot water systems are generally not recommended.
Preface 3. Features of socket welding type:
The installation is slightly more troublesome than the above two, but it is a jointless connection, which is safer and more reliable. There is no sealing ring inside and it is a dead connection. It has a wide range of applications and can be installed in the open or concealed. It is suitable for both cold water systems and hot water systems. After installation, it can be used once and for all, and there is basically no need to think about maintenance. This type of connection has been used on copper pipes for many years, and the Ministry of Construction now also recommends this type of jointless connection for stainless steel connections.
(1) The order of cost price and sales price from high to low is: Order 1>Order 2>Order 3.
(2) Sequences 1-2 are on-site assembly (need to borrow special tools) installation, fast and simple, suitable for surface installation. When the function of the rubber ring is lost, the nut can be removed in step 1 and replaced. The dead connection in step 2 should be sawed off and replaced. Preface 3 is suitable for concealed burial and wall embedding, and of course, can also be exposed.
(3), Preface 1: A brief introduction to the installation of the convex type: special installation tools are required during installation. When installing pipes with a diameter of DN15-50 (DN15-20), a special tool is used to ring and clamp the outer wall of the pipe. Set, (DN25-50) diameter pipe is installed by using a tool to protrude a ring-shaped step on the inner wall of the pipe.
(4), Preface 2 A brief introduction to the clamping type installation: Special installation tools are required during installation. The installation range is DN15-100. Insert the pipe into the pipe fitting and use special tools to clamp the pipe wall into a hexagonal shape. The internal seal The circle also transforms into a hexagonal shape.
(5) Sequence 3 welding type (socket argon arc welding type): The installation range is DN15-100. During installation, insert the pipe into the pipe fitting, and use an argon arc welding machine to weld and melt the originally reserved extended slope on the pipe fitting. No need Other solders are body welding and the construction is simple. (Butt argon arc welding type) The installation range is DN125-200. During installation, align the ports of the pipe and pipe fittings and weld them with an argon arc welding machine, but stainless steel electrodes are required as solder. Construction is somewhat difficult.
(6) Buried pipes should try their best to meet the requirements of the same life span as the building. Therefore, water pipes should be connected without joints first. The service life of stainless steel pipes can reach 70-100 years, which refers to pure stainless steel pipes without other rubber rings and other materials. At the same time, buried pipes are required to reduce joints as much as possible (one more joint means another potential leakage hazard). Most high-end buildings that use metal pipes (stainless steel pipes, copper pipes) use welded connections.
(7) The products produced by Bestar Steel are designed with special extended bevels for socket-type pipe fittings, which replace the addition of additional welding wire during welding. In addition to saving materials and labor, it is more ideal for the main body material to be melted into one after being hot-melted. For the connection of water pipes in high-end buildings, wall-embedded copper pipes should be welded by hardware, and stainless steel pipes should be welded by argon arc. Its characteristics are that tungsten argon arc welding has argon gas protection and is easy to use. The argon arc temperature is high and the heat is concentrated. The argon gas flow has a cooling effect on the welding area. The heat-affected zone is small and the welding process is stable. Therefore, in concealed or wall-embedded situations, welding (argon arc welding) is the most ideal connection method for stainless steel water pipes.
Socket welded pipe fittings have the following advantages:
1. It absorbs the advantages of simple socket insertion of mechanical connections such as convex type and pressing type;
2. Avoid the thorny problem of different lifespans of stainless steel and rubber rings (the latter will fail prematurely);
3. The connection of socket welded pipe and fittings is much simpler than butt welding;
4. The pipe wall of the pipe matched with the socket welded pipe fittings is relatively thin, which is in line with the national policy of material saving and energy saving, and has better cost performance.
5. No welding wire is required during the welding process (replaced by an extended edge). Not only can the pipeline material be integrated and the quality is 100%, but welding accessories can be omitted, the welding speed can be increased, and the welding quality can be ensured;
6. It is a connection method commonly known as “jointless connection”;
7. After pressure resistance, air tightness, drawing, and negative pressure tests, various data show that the pipe fittings connection strength and sealing performance have obvious advantages over mechanical connection methods;
8. It has a wide range of applications. In addition to exposed installation and concealed installation, “jointless connection” has special advantages in complex situations such as pipe wells and embedded walls.
Post time: Sep-12-2023