FAQ

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Callout to “POLYETHYLENE PIPE (PE)” on the Product Range Page

PN refers to the “Nominal Pressure” class rating of the pipe or fitting, measured in bar at 20 degree C. i.e. If a pipe has a PN rating of 16, its maximum recommended pressure to withstand is 16 bar at 20 degree C.
SDR refers to the “Standard Dimension Ratio” method of rating pressure piping. The SDR is the ratio of the pipe diameter to the wall thickness. i.e. A pipe with an SDR of 11 means that the diameter is 11 times the thickness of the wall of the pipe.
• A high SDR ratio – the pipe wall is thin compared to the pipe diameter
• A low SDR ratio – the pipe wall is thick compared to the pipe diameter

HDPE Pipe is mostly available in BLACK and can be used for all applications. Colour coding of PE pipe in the form of four stripes running the length of the pipe allows for easy identification of the material it is carrying. This allows for easy identification when excavating and during site works to determine the application the pipe is being used for.
• Yellow Stripes – Gas
• Blue Stripes – Potable Water (This also be Black Pipe)
• Red Stripes – Fire
• Cream Stripes – Sewer
• Purple Stripes or all Purple – Recycled/Reclaimed

Callout to “POLYETHYLENE PIPE (PE)” on the Product Range Page

Callout to “POLYETHYLENE PIPE (PE)” on the Product Range Page

Callout to “POLYETHYLENE PIPE (PE)” on the Product Range Page

Callout to “POLYETHYLENE PIPE (PE)” on the Product Range Page

A ‘short spigot’ fitting is shorter in length and generally less expensive. The disadvantage of short spigot fittings is that some Butt welding machines are limited to clamping the material and achieving a successful butt weld. You may also have to add pipe in achieve a required measurement and therefore carry out extra butt welds.
A ‘Long Spigot’ fitting has the opposite characteristics. Disadvantages being that achieving a shorter distance the welder may have to cut out/shave down large amounts of material to create the required distance.

Callout to “BACKING RINGS” on the Product Range Page

To measure the dimensions of a backing ring is to find the value of the PCD or K length referenced on the Backing Ring tables in the previous question. To find this value you simply measure the centre of one of the holes on the backing ring to the centre of the opposite hole. From this measurement you can then refer to the column labelled ‘K’ to see what ‘Table’ backing ring is required.

Callout to to “FITTINGS WITH LONG SPIGOT & FITTINGS WITH SHORT SPIGOT” on the Product Range Page

Callout to to “ELECTRO FUSION FITTINGS” on the Product Range Page

Electrofusion is a method of joining HDPE and other plastic pipes using special fittings that have built-in electric heating elements which are used to weld the joint together.
The pipes to be joined are cleaned, inserted into the electrofusion fitting (with a temporary clamp if required) and a voltage (typically 40V) is applied for a fixed time depending on the fitting in use. The built in heater coils then melt the inside of the fitting and the outside of the pipe wall, which weld together producing a very strong joint. The assembly is then left to cool for a specified time.

Electrofusion fittings are available as Tee’s, Reducing Tees, Saddles and Elbows and come in a large range of sizes.
Callout to “ELECTRO FUSION FITTINGS” on the Product Range Page

Yes, you just have to match the PCD or K value of each backing ring and correlate that measurement to the corresponding backing rings of both HDPE and PVC.

Callout to “POLYETHYLENE FITTINGS (PE)” on the Product Range Page

Callout to “FITTINGS WITH LONG SPIGOT & ELECTRO FUSION FITTINGS” on the Product Range Page

Callout to “FITTINGS WITH LONG SPIGOT & ELECTRO FUSION FITTINGS” on the Product Range Page

Dalkeith Plastics Pty Ltd follows the Plastic Industry Pipe Association (P.I.P.A.) guidelines.

For more information visit www.pipa.com.au

Industry Guidelines

www.polysmart.com.au

Yes, there are a few different ways welds can be tested.

They are as follows:
• Mechanical Tensile Test
• Bend Test
• ToFD Test
• Hydrostatic Test

Ultimate Tensile Strength (UTS), often shortened to Tensile Strength (TS) or Ultimate Strength, is the maximum stress that a material can withstand while being stretched or pulled before failing or breaking. Some materials will break sharply, without plastic deformation, in what is called a brittle failure. Others, which are more ductile, including most metals, will experience some plastic deformation and possibly necking before fracture.

Bend Test performs a qualitative test of a fusion joint by destructively testing a coupon. The quality assurance device tests the ductility of polyethylene pipe fusion joints in a safe, quick manner. “Bend back” tests have been performed in the field for years. This testing method places the entire wall thickness into tension and gives assurance of the ductility of joints.
A hydraulically powered test unit puts three points of pressure on test coupons. If no gaps or breaks are present in the fusion joint after the test, the result is a passing grade. The Guided Side-Bend Tester is lightweight, and requires the operator to supply a planer, callipers and saw to complete the testing procedure.

Ultrasonic time-of-flight-diffraction (TOFD) inspection of fusion joints is an easily employed nondestructive examination tool that can be used to provide additional assurance of fusion-joint integrity.
A conventional TOFD procedure is used for the inspection of HDPE, with the following specifications:
• The probe centering spacing (PCS) is adjusted to provide beam cross at 66% of the thickness. Additional configurations are recommended on thick-wall pipes to improve detection near the OD or ID surfaces.
• The probe assembly is mounted on the Chain scanner.
• Electronic gain on the OmniScan is adjusted to set the lateral wave (LW) signal at 60%.
• The CHAIN scanner is mounted on the pipe, and the inspection is performed in one rotation.

The pipeline is filled with water, bleed off any trapped air. Subject the lowest element in the system to a test pressure that is 1.5 times the design pressure, and check for any leakage.

The test procedures consist of two steps; the initial expansion and the test phase. When test pressure is applied to a water filled pipe, the pipe expands. During the initial expansion of the pipe under test, sufficient make-up water must be added to the system to maintain the test pressure. After a period of time the initial expansion should be complete and the actual test can start.

When the test is to begin, the pipe is full of water and is subjected to a constant test pressure of 1.5 times the system design pressure or Engineer specifications. The test phase should not exceed 3 hours.

The hydrostatic system should have dual pressure gauges that are calibrated within a 1 year period. The system should also have a “pressure release valve” set at the rating of the pipe being tested. This valve should also be calibrated within a 1 year period to ensure pressure does not exceed the rating of the pipe being tested.

Callout to “FITTINGS WITH LONG SPIGOT & ELECTRO FUSION FITTINGS” on the Product Range Page

Callout to “FITTINGS WITH LONG SPIGOT & ELECTRO FUSION FITTINGS” on the Product Range Page

Yes, a “Bead” is the excess plastic material expelled from the weld zone when the pressure is applied in the process of butt welding. This can be removed externally and internally without affecting the integrity of the weld.

It may be removed externally for aesthetic reasons or more commonly for the process of “sleeving” or “Close Fit Lining” where the bead may hinder the process of placing the pipe inside another pipe.

The internal bead may also be removed for the purpose of eliminating a “catch point”’ on material travelling through the pipe. This is carried out with an “Internal de-beader”.

Callout to “POLYETHYLENE PIPE (PE)” on the Product Range Page

Yes, certain recyclers will pay a per kilo price for HDPE material.

Yes, Dalkeith Plastics Pty Ltd can fabricate any size segmented bends on special orders. Using a variety of templates available the workshop team can make any angled bends in any quantity required.