PVC / HDPE Pipes & Fittings
There are many different types of pipe available on the market with different material properties. Depending on the application, engineers will require pipe of a particular style to suit their requirements.
Material properties include physical properties (e.g. density and molecular weight), electrical/thermal properties and mechanical properties. Mechanical properties (such as strength, durability, ductility and impact strength) are all measurable and used during standard testing.
Pipe can be broadly broken down into three different products – Polyvinyl Chloride (PVC) products, Polyethylene (PE) products and Polypropylene (PP) products. The two main pipe and fittings products stocked by DEPS are PVC and HDPE – there is more information below regarding these.
PVC
Polyvinyl chloride is a material which consists of PVC resin compounded with varying proportions of lubricants, fillers, stabilisers, pigments, plasticisers and processing aids. Different compounds of these ingredients have been developed to obtain specific groups of properties for different applications – this changes the class of pipe. However, the major part of each compound is PVC resin.
PE (LDPR, HDPE and other Polyethylene products)
Polyethylene materials are manufactured from natural gas derived feedstocks by two basic polymerisation processes. The low pressure polymerisation process results in linear polymer chains with short side branches. Density modifications to the resultant polymer are made by varying the amount of comonomer used with the ethylene during the polymerisation process.
LDPE – Low Density Polyethylene is more frequently used in very low pressure applications and is used largely in the food and beverage industries. It can withstand temperatures to 80C and has descent chemical resistance.
- Excellent resistance (no attack/no chemical reaction) to dilute and concentrated acids, alcohols, bases and esters
- Good resistance (minor attack/very low chemical reactivity) to aldehydes, ketones and vegetable oils
- Limited resistance (moderate attack/significant chemical reaction, suitable for short-term use only) to aliphatic and aromatic hydrocarbons, mineral oils, and oxidizing agents
- Poor resistance, and not recommended for use with halogenated hydrocarbons.
HDPE – High Density Polyethylene, all Poly Pipes in Australia are currently made from HDPE material. Whether it’s blue line or rural pipe, HDPE is made to AS/NZS 4130. It has uses far beyond pipe and it’s chemical resistance is equal to and better than LDPE.
- Excellent resistance (no attack/no chemical reaction) to dilute and concentrated acids, alcohols, bases and esters
- Good resistance (minor attack/very low chemical reactivity) to aldehydes, ketones and vegetable oils
- Limited resistance (moderate attack/significant chemical reaction, suitable for short-term use only) to aliphatic and aromatic hydrocarbons, mineral oils, and oxidizing agents
- Poor resistance, and not recommended for use with halogenated hydrocarbons.
MDPE – Medium Density Polyethylene and are not currently used in Australia.
PE100 – PE100 is a version of HDPE and refers directly to the Minimum Required Strength (MRS) of 100% at 50 years and 20º according to ISO4427.
PE80 – As above with Minimum Required Strength (MRS) of 80% at 50 years and 20º according to ISO4427.
PE – PE is short for Polyethylene and is used to describe all types of Poly Ethylene pipe.
Poly Ethylene – Polyethylene is the name of the material that makes up Poly Pipes, as well as other items, such as water tanks.
And now for the ratings!
SDR Rating – Standard Dimension Ratio. When the outside diameter of the pipe is divided by the SDR, it gives the thickness of the pipe wall.
PN rating – Pressure Nominal. When a pipe has a rating of PN12, it refers directly to Bar. 1 BAR is equal to 14.7 psi. So 12 x 14.7 psi = 176.40 psi, therefore a pipe with a PN12 rating can be pressurized to 176 psi.
