SRTP pipe - perfect combination of metal pipe & plastic pipe

What is a plastic pipe?

Plastic pipes are generally made of synthetic resin, that is, polyester, as raw materials, adding stabilizers, lubricants, plasticizers, etc., and are extruded in a pipe-making machine by a "plastic" method. Mainly used for water supply system piping, drainage, exhaust and sewage sanitary pipes, underground drainage pipe systems, rainwater pipes and threading pipes for wire installation in housing construction.

Plastic pipes are divided into two categories: thermoplastic pipes and thermosetting plastic pipes. The thermoplastic ones include polyvinyl chloride pipes, polyethylene pipes, polypropylene pipes, polyoxymethylene pipes, etc.; the thermosetting ones include phenolic plastic pipes.

Among non-metallic pipes, the most widely used are plastic pipes. When plastic pipes first appeared, they were used to replace metal pipes. As the performance of plastic pipes became more and more superior, the application range of plastic pipes became larger and larger. Now, all aspects of life are inseparable from plastic pipes.

Plastic pipes have the following advantages

1. The first point is light weight, because its density is only 1/7 of that of cast iron, so it is very easy to transport and install. Great cost savings.

2. The second advantage is that the pipe wall is smooth, so when transporting water or other liquids, the fluid flow resistance will be much smaller, much smaller than that of cast iron pipes, and the flow rate is nearly 1/3 higher than that of cast iron pipes. .

3. The third advantage of plastic pipes is corrosion resistance. Whether it is acid-base liquid or gas, etc., there is basically nothing to do with plastic pipes. Therefore, compared with metal pipes, plastic pipes can be said to be the general existence of long-lived old people, such as rigid PVC. , its lifespan can reach up to 50 years. The pipes survive for a long time and do not need to be maintained or replaced all the time, which greatly saves costs.

4. The fourth advantage of plastic pipes is energy saving and low price. This aspect of energy saving is mainly from the processing of plastics. Plastic processing does not require high temperature, so plastic consumes less energy, and the energy saving effect is far greater than that of metal pipe production.

Disadvantages of plastic pipes

Can plastic pipes completely replace metal pipes? The answer is: no! Although plastic pipes first appeared to replace metal pipes, as the performance of plastic pipes becomes more and more superior, the application range of plastic pipes is also increasing. In many fields, plastic pipes have indeed replaced metal pipes, but they are not All fields. Nothing is perfect. Plastic pipes also have the following disadvantages, which is why metal pipes have not disappeared so far.

1. First of all, we all think that plastic is not heat-resistant. Steel will melt unless it is at a particularly high temperature, but because plastic pipes are thermoplastics, they must be kept away from high temperatures when in use, otherwise the pipes must be replaced.

2. In addition, plastic pipes have the disadvantages of low impact resistance and large thermal expansion coefficient, which cannot cope with various accidents, such as violent impacts.

Disadvantages and advantages of metal pipes

And metal pipes also have their own shortcomings, otherwise they will not be replaced by plastic pipes in many fields. Its disadvantages are heavy weight and high cost. Although it is harder than plastic pipes and can resist various external impacts, it is not resistant to corrosion.

Is there a perfect combination of metal pipe & plastic pipe?

At this time, we urgently need a kind of pipe that can perfectly integrate the advantages and disadvantages of the two. This kind of pipe only retains the advantages of the two and eliminates the disadvantages of the two. Does this kind of pipe really exist? Exist, it is steel mesh skeleton polyethylene composite pipe.

The steel mesh skeleton polyethylene composite pipe is a mesh skeleton formed by spiral winding of high-strength steel wire left and right as the reinforcement, high-density polyethylene (HDPE) as the matrix, and high-performance HDPE modified bonding resin is used. A new type of pipe with the outer layer of high-density polyethylene tightly connected together. It also has another name, SRTP pipe. This special pipe is actually a combination of plastic and steel. Its powerful composite effect has been widely loved by consumers since its birth.

Because the high-strength steel wire reinforcement is encapsulated in continuous thermoplastic, the steel mesh skeleton polyethylene composite pipe overcomes the respective disadvantages of the steel pipe and the plastic pipe, while maintaining the respective advantages of the steel pipe and the plastic pipe.

The steel mesh frame polyethylene composite pipe adopts high-quality material and advanced production technology, so that it has higher pressure resistance performance. At the same time, the composite pipe has excellent flexibility and is suitable for long-distance buried water and gas pipeline systems. The pipe fittings used in the steel mesh skeleton polyethylene composite pipe are polyethylene electrofusion pipe fittings. When connecting, the outer layer plastic of the pipe and the inner layer of the pipe are melted by the heating body inside the pipe, so that the pipe and the pipe are connected together reliably.

Using High Density Polyethylene (HDPE), strong steel wire helically wound frame to create high tensile strength to strengthen the body. Using High Density Polyethylene (HDPE) as the raw material results in a lightweight tubing that resists aggressive chemicals and can withstand freeze-thaw cycles and sustained sub-zero temperatures without cracking. HDPE is highly abrasion resistant and is not affected by acidity or alkalinity. But that's not all - HDPE fuses have strong steel wire and a lightweight, flexible tube for high tensile strength and durability. Most importantly, our low-cost dedicated electrofusion fittings, pipe-to-pipe connections, are installed without compromise. Due to these qualities, SRTP pipes are often used in urban water supply, civil engineering, oil and gas fields, chemical industry, power transmission pipelines, metallurgical mines, seawater transportation, shipbuilding, agriculture and laying fiber optic cables.

Characteristics of steel mesh skeleton polyethylene composite pipe

The steel mesh skeleton polyethylene composite pipe has the common characteristics of anti-corrosion, non-scaling, smooth and low resistance, thermal insulation, non-waxing, wear-resistant, light weight and other plastic pipes, and its unique structure also creates the following characteristics:

(1) Good creep resistance and high lasting mechanical strength

Because plastic will creep under normal temperature and stress, and brittle fracture will occur under higher permanent stress, so the allowable stress and pressure bearing capacity of pure plastic pipes are very low (generally within 1.0Mpa). The mechanical strength of steel is about 10 times that of thermoplastics, and it is very stable and does not creep within the temperature range of plastics. After the mesh wire skeleton is compounded with the plastic, the steel mesh skeleton can effectively restrain the creep of the plastic and greatly improve the lasting strength of the plastic itself. Therefore, the allowable stress of the steel mesh skeleton polyethylene composite pipe is doubled compared with that of the plastic pipe.

(2) Good temperature resistance

The strength of plastic pipes generally decreases with the increase of temperature within the range of their use temperature, and the strength decreases by more than 10% for every 10 °C increase in temperature. Since about 2/3 of the strength of the steel mesh skeleton polyethylene composite pipe is borne by the steel mesh skeleton, its strength decreases with the increase of the use temperature than any pure plastic pipe. The experimental results show that the strength of the steel mesh skeleton polyethylene composite pipe decreases by less than 5% for every 10 °C increase.

(3) Rigidity, good impact resistance, good dimensional stability, and moderate flexibility, combining rigidity and flexibility

The elastic modulus of steel is usually about 200 times that of high-density polyethylene. Due to the reinforcing effect of the steel mesh skeleton, the rigidity, impact resistance and dimensional stability of the steel mesh skeleton polyethylene composite pipe are better than any pure Plastic tubing. At the same time, because the mesh steel skeleton itself is a flexible structure, the composite pipe also has certain flexibility in the axial direction. Therefore, the pipe has the characteristics of rigid and flexible combination, and has excellent performance in the adaptability of loading and unloading, transportation, installation and operation reliability. Above-ground installation can save the number of supports and low cost; underground installation can effectively withstand sudden shock loads caused by settlement, slip, vehicles, etc. Small-diameter pipes can be properly bent and arranged in undulating terrain or serpentine, saving pipe fittings.

(4) Small thermal expansion coefficient

Since the linear expansion coefficient of steel wire for plastic pipe is 10.6~12.2×10-6 (1/℃), and the linear expansion coefficient of pure plastic pipe is 170×10-6 (1/℃), the steel mesh skeleton polyethylene composite pipe is in mesh steel. Under the constraint of the skeleton, the thermal expansion of the composite pipe is greatly improved, which is lower than that of any commonly used plastic pipe. Through the test, the expansion coefficient of the steel mesh skeleton polyethylene composite pipeline is 35.4 ~ 35.9 × 10-6 (1/℃), only It is 3 to 3.4 times that of ordinary carbon steel pipes. The experimental results show that the thermal compensation device is generally not needed for buried installation, and the pipes can be absorbed (or released) by serpentine laying, thereby reducing the installation cost.

(5) Rapid cracking will not occur

Under the action of persistent hoop stress at low temperature, pure plastic pipes, especially large-diameter pure plastic pipes, are prone to rapid cracking caused by local defects and stress concentration (hundreds of meters to more than kilometers in an instant). The rapid cracking resistance of plastics puts forward high requirements, while low carbon steel does not have the problem of brittle fracture. The existence of steel mesh prevents the deformation and stress of plastics from reaching the critical point for rapid cracking. Therefore, in theory, there is no rapid cracking of the steel mesh skeleton polyethylene composite pipe.

(6) The composite of steel and plastic is uniform and reliable

At present, the steel-plastic composite pipe on the market is a continuous and regular interface because the composite surface between steel and plastic is easy to be delaminated under the action of alternating stress for a long time, resulting in leakage at the joint, internal bottleneck-like shrinkage, and blockage and failure. . Compared with it, the steel mesh skeleton polyethylene composite pipe is a mesh structure through a special hot melt adhesive (modified HDPE), which makes the plastic and the steel mesh tightly combined and integrated. The mutual binding force of the two materials is large and uniform, and the stress concentration is small.

(7) Double-sided anti-corrosion

The steel mesh skeleton is compounded in plastic through a special hot-melt adhesive layer. The inner and outer surfaces of the pipe have the same anti-corrosion performance, wear resistance, smooth inner wall, small transportation resistance, no scaling, no waxing, and obvious energy saving effect. It is used for buried transportation and More economical and convenient in corrosive environments.

(8) Good self-traceability

Due to the existence of the steel mesh frame, the buried steel mesh frame polyethylene composite pipe can be located by the usual magnetic detection method to avoid damage caused by other excavation works. And this kind of damage is the most damage to pure plastic pipes and other non-metallic pipes.

(9) The adjustment of product structure and performance is convenient and flexible

The structure and performance of the product can be adjusted by changing the steel wire diameter, mesh spacing, plastic layer thickness, plastic and type to meet different pressure, temperature and anti-corrosion requirements.

(10) Special electrofusion joints, various varieties, very fast and reliable installation

The connection of steel mesh skeleton polyethylene composite pipe adopts two methods: electric heat fusion connection and flange connection. The electrothermal fusion connection is to insert the composite pipe into the electrothermal fusion pipe fitting, and energize the electric heating wire embedded in the inner surface of the pipe fitting to make it generate heat. First, the inner surface of the pipe is melted to generate a melt, the melt expands and fills the gap between the pipe and the pipe, until the outer surface of the pipe also produces a melt, and the two melts are melted together. After cooling and forming, the pipe and the pipe are tightly connected as a whole.

So, if you want to say which kind of pipe can realize the perfect combination of metal pipe and plastic pipe, it is the steel mesh skeleton polyethylene composite pipe.