How are HDPE corrugated pipes made?
Polyethylene (PE) is by far the most common type of consumer plastic, and is used in many everyday materials. It is a thermoplastic product, which means that it can be melted into a liquid and then cooled back into a solid. Different processing conditions give rise to different grades of polyethylene that can be used for different purposes. Especially, HDPE corrugated pipes are manufactured in a large quantity and appear almost everywhere in the world, from industrial sites with huge water pipes systems to household tool kits. In this article, we will find out how are HDPE corrugated pipes made.
- What are corrugated pipes?
A corrugated pipe is a pipe with a series of ridges and grooves running parallel to each other on its surface. The ridges and grooves follow a pattern that is perpendicular to and bisecting the centerline of the pipe. Corrugated pipes are made of different materials such as iron, steel, polyvinyl chloride (PVC), or high-density polyethylene (HDPE).
Corrugated pipes are used where flexibility is an important factor other than strength and durability, such as in storm drains and culverts. Flexibility makes corrugated pipes more useful and suitable for a wide variety of uses compared to rigid and non-corrugated pipes.
The range of applications to which corrugated pipes can be put to can be attributed to its flexibility. The height of the ridges in a corrugated pipe determines its degree of corrugation; the higher the number, the greater its flexibility. Of the different types of corrugated pipe materials, HDPE is considered as the most versatile, flexible, durable, and long-lasting. HDPE is considered suitable for use in underground structures, due to its light-weight and non-brittle properties. It is also easy to transport and install, reducing the overall cost of a project. 
2. Advantages of corrugated pipes extrusion line
- Material saving
When manufacturers apply corrugated pipes extrusion line, they will save up to 60% of raw materials compared to manufacture solid walled pipes.
Though they are lighter, these pipes are strengthen by the rings in their structure.
- Easy handling
Corrugated pipes are lighter, which makes them easy to handle and transport. Therefore, people will require less personnel for corrugated plant and the same benefits will trickle down to the end user.
- Less ecological footprint
By cutting down on the material used, corrugated pipes extrusion line will have far less impact on the environment. In addition, corrugated pipes extrusion line produces less carbon dioxide emission compared to making concrete pipes.
Furthermore, it is easy for manufacturers and end users to recycle corrugated pipes.
3. HDPE corrugated pipes extrusion line 
Corrugated pipes extrusion line now is rapidly developing in technology, production process and the control while production. In addition to the abovementioned definitions, a HDPE corrugated pipes extrusion line could be divided into 5 stages including:
- Preparation of the raw material
This is an important stage in the production process since it requires the collaboration of the staff in different levels. Preparation of the raw material starts with the purchase order and ends with making the mixture and transferring it to the extruder funnel. This stage is directly related to the production plans. This phase consists of: purchase order, receiving, storing and making the mixture.
- Provision of the raw material:
The raw material used in corrugated pipes extrusion lines are approved by the employees in an operational team as production, guarantee of quality and purchase, based on technical specifications of the raw material, the required criteria for product standards, reliability of the supplier and quality control tests of the raw material and the products made from it. In case the raw material would possess the desired quality, it will be ordered and purchased.
- Receiving and storing of the raw material:
The raw materials are sampled and evaluated by the quality control agent upon arrival at the factory. In case that the shipment was in conformity with the requested specifications based on the specs out on the specifications documents of the products and the bill of lading, the quality control agent will perform the standard tests on the samples to determine the conformity of the shipment and to provide report. In case of any discrepancy in the specifications of the raw material with the relevant standards, the shipment will be returned.
The tests performed on the raw materials are as follows:
- melt flow index (MFI)
- density test
- oxidative induction times (OIT)
- humidity test
- soot dispersion test
- Extrusion
In the extrusion stage of thermoplastics, the polymers are melted by the heat created inside the extruder. Melting of heavy PE is controlled by precise adjustment of the thermal profile in different areas based on the polymer type which results in optimum pressure in the extruder output. This task is performed by the production personnel according to the guidance instructions for quality control and method.
- Corrugation
After the extrusion, the HDPE has passed through die and gets the pipe shape at the die output. Then the corrugating process of outer surface of the double wall pipe is performed by applying die and vacuum, while the inner surface of the pipe is still smooth. Such molding process is continuously performed by corrugating rotary dies.
Based on type of the desired pipe, respective parts and dies are installed on the production line and during the production process, stabilization of thickness of polyethylene pipe layers, production speed and temperatures are adjusted at their optimum. The quality control agent performs the necessary controls on the final products to ensure the desired quality is achieved.
- Calibration
The cooling stage is essential for stabilization of the dimension in production of plastic pipes which is named as calibration and is different based on the pipe thickness and production speed. In order for cooling of the pipes, the water nozzles are used which are embedded all around the pipe along the calibrator. The water temperature of the cooling system is also under control.
- Confirmation and final products tests
In the final stage of the corrugated pipes extrusion line, the corrugated pipe is sampled and the quality control unit performs the respective tests to determine whether the final product is in conformity with the required specification and also optimizes the adjustments.
The production process, the stages from stage 2 to 5 are controlled by the production personnel and quality control agent. Finally, the quality control unit samples the products and does the final confirmation according to the standard tests
4. Masterbatch in HDPE corrugated pipes extrusion lines
Masterbatch is an important raw material in HDPE corrugated pipes extrusion line. Manufacturers use CaCO3 filler masterbatch mainly for reduction of material cost, color masterbatch for color making and additives masterbatch for other properties improvement. Masterbatch appears to bring the best solution to manufacturers regarding saving production cost and enhancement products properties as well.
As a leading manufacturer of CaCO3 filler masterbatch, color masterbatch and additives masterbatch in Vietnam with over 13 years of experience, US Masterbatch is proud to supply high-quality masterbatch with competitive rates to numerous manufacturers in 80 countries around the world, in which companies play a big scale in exported quantity.
| CaCO3 filler masterbatch | Black masterbatch | |
| Melting Flow Rate | 0.6g/10mins | 50g/10mins |
| Bulk Density | 1.1g/cm3 | |
| Humidity | 0.08wt% | 0.08wt% |
| Processing Temperature | 140-280°C | 140-280°C |
Masterbatch from US Masterbatch bring outstanding features as below:
- Reduce production costs
- Increase hardness and durability as well as not losing color and transparency of the product.
- Glossy, soft, flexible surface with good water resistance.
- Food contact and children contact recognized by FDA, REACH, ROHS, etc.
- Withstand high temperatures in a short time.
- Raw materials are available from nature, safe, low cost, and easy to use for the production of the plastic industry.
