Pvc Pipes Manufacturing Process 5cn4o

What is a PVC Pipe? 

PVC pipes are made out of a material known as polyvinyl chloride, a durable, strong plasticlike substance. Pipes are constructed from this material and used in various applications from plumbing to construction. The pipe is designed to be universal. All pipes are designed around specific requirements to ensure that multiple pipe sections will fit together. The ends of the pipe can either be smooth or grooved (similar to a screw). Additionally, there are several different pipe sizes ranging from very small (one-fourth inch) to very large (10 feet). Currently, PVC piping counts for the majority of plumbing in the U.S. and is the preferred standard for new construction.

How is it Made? 

PVC pipes are created by starting with a molten mixture of the material and shaping them around a cast. The casts are made to be the exact width of the pipe. The mixture is poured into a cast and surrounded by an outer shell. The complete set is then placed into an oven to be cooked. Once the pipe has solidified, it is cooled and moved into finishing. Sections of the pipe are then cut based on common sizes and needs. The sections are then coated in a chlorine solution to prevent harmful bacteria from growing during shipping and use. Once the coating is dried, the ends of each section are finished. If the pipe is a smooth connection, the top of the pipe is sanded down to ensure a perfectly flat surface. For fitted pipes, a machine engraves a series of grooves into the pipe. As the grooves are cut, high-pressured water is sprayed on the pipe to remove excess PVC fragments. After the grooves are added, the ends are smooth and the sections are sent into testing.

Quality Control 

Because PVC pipes are used in many housing and commercial construction applications, it is important that each pipe is tested to ensure quality. To do so, the pipes are tested for their seal, connection (on grooved sections), and strength. The seal tests are conducted by adding a special cement to the pipe and allowing it to dry. Once this is complete, a series of liquids are ed through the pipe at high pressure. If no leaks occur, the cement is removed and the section is cleaned. For fitted pipes, a similar process takes place without the cement. The final test of the pipes is to ensure their strength. This is completed by using several presses that push weight down on the pipe. If the section does not break or show stress points, it is sent for packaging and shipping. If a section fails at any point in the process, it is sent back to be melted down and re-constructed.

Ingredients of PVC Pipe Manufacturing Raw Materials 

The two raw materials used in the manufacture of PVC are sea water and oil. Salt derived from sea water is used to make chlorine gas and petroleum oil is the original source for ethylene gas. Chlorine and ethylene are the two main ingredients needed to make PVC.

Chlorine



Chlorine is produced from a saline solution by the process of electrolysis. A solution of sodium chlorine, or common table salt, is placed in a container with electrodes. When electric current is applied, the positive electrode attracts chloride ions in the solution where they combine to form chlorine gas.

Ethylene 

Ethylene is a colorless and odorless gas with the chemical formula C2H4. It is highly flammable and can cause explosions if mishandled. It is produced commercially from the refining of petroleum.

Making PVC 

The chlorine and ethylene gases are combined to produce ethylene dichloride which is converted at high temperatures to vinyl chloride (CH2=CHCl). The vinyl chloride molecules are then polymerized to form the PVC resin. Other compounds are added to improve its appearance and physical and chemical properties. The finished product is formed into pipe or other products where it hardens as it cools.

Additives 

A number of compounds can be added to raw PVC. The most common additives are pigments to add color, UV inhibitors to protect the material from being degraded by prolonged exposure to sunlight, and plasticizers to adjust the degree of flexibility of the specific product. Most plasticizers come from a chemical group called phthalates.

Toxicity of Materials 

Chlorine in the gaseous form is dangerous because it is a severe irritant to the skin, eyes, and respiratory system. Ethylene chloride compounds that are made in the manufacturing process and not converted into polymers are known to be carcinogenic. There are remnants of these compounds that are not combined in the finished PVC which makes water pipe and other products potentially hazardous as well. The phthalates that are used as to increase plasticity are also very toxic.

Production process of PVC pipe extrusion line PVC pipe extrusion line is one of the most common plastic pipe machine. The production process of PVC pipe extrusion machine are as follows: 1. First of all, Mixing the raw material. Put the PVC stabilizers, plasticizers, antioxidants and other excipients in proportion into the high speed mixer according to the process order, when the mixer working, the material are warmed to the setting process temperature by the friction function between materials and machinery, and then by cold mixing machine the material was dropped to 40-50 degrees. Then the mixed material can be put into the hopper of the extruder. 2. The extruder working: The machine is equipped with a dosing device which can ensure the extrusion amount and feeding amount and ensure that the products can be stable extrusion. Due to the characteristics of the conical screw, the feed section has a larger diameter, the heat

transfer area and the shear rate of material are relatively large, which if beneficial for material plasticization. 3. Extrusion die function: The compaction, melting and kneading PVC are pushed to the extrusion die head by the homogenized subsequent material, the extrusion die head is the crucial parts for pipe molding. 4. Vacuum calibration tank is used for pipes cooling and stereotypes. The vacuum sizing tank is equipped with vacuum stereotypes and cooling system and water circulation system, adopting stainless steel cabinet, circulating water spray cooling. 5. Haul-off machine (tractor) is used for pull the cooled and hardened pipes out from the die head continuously and automatically, and frequency controls the speed. 6. Cut pipes by cutting machine: automatically cutting according to the requirements length of the control by the travel switch, and turning frame in a seted delay time. To know the detialed of each steps and more introduction of our plastic pipe production line, please us, our technical workers will describe it in detail for you.