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FAQ

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What is the maximum flow velocity for HDPE?
In a pumped system, the maximum operating velocity is limited by the surge pressure capacity of the pipe. The Plastics Pipe Institute’s Handbook of Polyethylene Pipe states that “if surge is not a consideration, water flow velocities exceeding 25 feet per second may be acceptable.”
How does the impact strength of PE compare with other pipes?
1. PE is a ductile material and has exceptional impact strength. As an example, AWWA publishes an Izod Impact resistance value of 10-12 ft-lbf/in for HDPE and of 0.65 ft-lbf/in. for PVC. PE superior impact strength provides a piping system that is near impervious to impact damage and to damage from improper tapping.
2. In the real world, engineers understand that pipes must be tough and resist impact and handling damage. PE pipes are field tested and proven to be impact tough.
Can HDPE pipe be hot or cold tapped to install service connections with fittings presently available?
HDPE pipe can be cold or hot/wet (under pressure) tapped using piping products presently available. Saddle fusion tapping tees, electrofusion tapping tees, Fuse-A-Corps, and branch-saddles are readily available in the industry. There are also bolt-on mechanical connections qualified for use with HDPE pipelines as well.
Are heat fused pipe joints safe?
1. Yes. Polyethylene pipe has been heat fused for almost fifty years in a wide range of service applications. The window of conditions that are acceptable for good quality fusion joints is broad, and the long term performance is documented in actual field applications as well as in long term testing. PE pipe joints are standardized through ASTM fusion procedures as well as recognized in AWWA, PPI, ASME, and other industry standards.
2. There are new technologies that attempt to mimic the advantages of PE fused joints for other pipe materials. However, these materials do not have the history, the proven performance, and the industry peer reviewed standardization of PE pipe fusion joints.
Can HDPE pipe be threaded?
No. Tapped threads are not recommended for use on PE. The industry standards for service taps to HDPE mains recommend the use of saddle fusion tapping tees, electrofusion tapping tees, Fuse-A-corps, branch-saddles, and certain metal mechanical clamps.
If HDPE pipe is punctured, how is it repaired?
When external third-party damage does occur, there are several repair methods. Punctures in PE pipe may be repaired using electrofusion repair saddles or mechanical repair clamps.
If the damage is sufficiently extensive that a pipe section must be removed, the pipe section may be replaced with a spool piece of the pipe connected on each end to the exiting pipe using mechanical fittings, electrofusion couplings, or flanged connections. Refer to the PPI Handbook on HDPE Pipe Repair and Maintenance.
Can I install HDPE pipe with the same embedment used for PVC and DI pipe?
Yes. The same embedment materials are generally suitable; however, the specific parameters of the application may influence this somewhat. For instance, very high DR pipes in shallow cover subjected to a live load may require a higher level of compaction for the embedment material than required by a lower DR PE pipe or stiffer pipe.
Is PE pipe a green solution for piping?
Yes. It is safe when manufactured, used, or incinerated. It helps preserve water and electricity as there is no water loss through its fused joints. No toxins are released during the creation or disposal of PE pipe.
Are there hazardous vapors or fumes that come off of HDPE pipe when it is cut?
There are no hazardous fumes associated with the cutting of HDPE pipe.
Does the fusion bead affect flow?
No. The Hazen Williams C factor of 155 was determined with pipe that was fused together and thus contained inner fusion beads.
Can I fuse and install HDPE pipe in sub-zero weather?
Yes. You have to protect the joint during cold weather fusion from wind, moisture, and blowing snow so that the heater plate uniformly heats the end of the pipes.
Where do I get the equipment to fuse HDPE pipes?
The equipment is readily available through distributors such as Hürner.
Can I pour concrete safely around HDPE pipe?
Yes.
Can I use a butterfly valve on HDPE pipe?
Yes. For PE pipe, connections to butterfly valves are usually made with Bevelled Flange Adapters. This prevents interference between the valve and the inside diameter of the pipe.
What are the safe maximum and minimum burial depths for HDPE pipe?
1. Safe burial depths vary and should be calculated. In lieu of calculations AWWA says that for an embedment soil with an E’ of 1000 psi and no surface water, HDPE pipes with DR’s ranging from 7.3 to 21 can be safely buried from a depth of 2 ft to 25 ft where no traffic load is present and from 3 ft to 25 ft where H20 live load is present.
2. Most pipes can be buried to deeper depths. Equations for calculating burial depth may be found in Chapter 6 of the PPI Handbook of Polyethylene Pipe.
What is the difference between MDPE and HDPE, PE80 and PE100?
Historically, PE pipe materials were designated by their density. So LDPE stands for Low Density PE, MDPE – for Medium Density PE and HDPE – for High Density PE. Higher density indicates higher material strength, but it does not relate to any other long term material properties, such as stress crack resistance.

With the introduction of international standards, PE80 and PE100 designations were introduced. The numbers relate to the MRS (Minimum Required Strength)value of the material. In the UK, materials classified as MRS8 are referred to as PE80 and materials classified as MRS10 are referred to as PE100.
PE100 is a higher performance material than PE80 and demonstrates exceptional resistance to rapid crack propagation as well as stress cracking. The higher strength of PE100 permits thinner pipe walls than PE80 for the same operating pressures. PE100 uses less polymer and provides for a larger bore and increased flow capacity for a given nominal pipe size. This can result in significant cost savings at certain sizes and pressure ratings.
Do you produce PE pipes against American ASTM standards?
No. Our pipes are made against European standards, such as EN 12201 and EN 1555, and not against American ASTM standards.
What are the PE100+ Quality Materials?
PE100+ Quality Materials are premium PE100 grades that comply with the enhanced requirements of the PE100+ Association. These materials are exceptionally resistant to rapid crack propagation and long-term stress cracking. All GPS Excel (PE100) pipes are manufactured in PE100 pipe grades, listed on the PE100+ Quality Materials List.
What is the difference between polyethylene and Alkathene pipes?
There no difference. Alkathene is just another proprietary name for polyethylene.
When pressurized the assembled fitting, water leaks from the connection joint?
a. Ensure the PE pipe used compliance to standard ISO4427/DIN8074/MS1058/EN12201 in term
of dimensional specification. Refer to the attached PE pipe dimension table.
b. Ensure the pipe end cut with even and flat surface.
c. Ensure the pipe insertion reach the inner stopper of the fitting body.
d. Fully tighten the locking nut with hand and with the help of strap wrench
What type of butt fusion and its min. requirement shall be used for butt fusion connection?
a. The butt fusion machine used shall certified to ISO12176-1by a recognized certification body (e.g:
SIRIM, DVT, Wrc).
b. A valid service and calibration record (min. once/ year)
c. Capable of performing the task it is designed for, i.e. machine sizes against pipe size, correct jointing parameters must be programmed etc.
d. Equipment should allow a printout of weld parameters and joint history for traceability.
What qualification needed for a butt fusion welder?
a. Welders must hold appropriate certificates recognised by the relevant Water Authority or training party. This is evidence that appropriate training has been carried out, and they are capable of welding correctly.
What other equipment shall be used during butt fusion joint at site?
Recommended minimum mandatory ancillary equipment are required to ensure a quality butt fusion connection.

• Shelters.
• Pipe support rollers.
• Indelible marker pens.
• Ground sheets or base boards.
• Clean cloths to wipe the pipes before trimming.
• Spirit Level to ensure machine is level.
• Bead size measurement tool.
How to determine the quality of butt fusion joint?
The following requirement shall be meet for a quality joint.

• Bead Appearance.
• No dirt contamination.
• The gap.
• Displacement.
• Bead Width.
What is the minimum requirement for an electrofusion welding unit?
The minimum requirement for electrofusion welding unit are as below:

a. A valid service and calibration record (min. once per year).
b. Valid certificate of calibration and service to ensure
• Output voltage is correct
• Timer is accurate
• Electrical safety
c. Capable of performing the task it is designed for e.g. compatible voltage to the fitting.
d. Equipment shall provide a printout of weld parameters and joint history to ensure joint quality
and traceability.
What should be carry on, if the barcode on the fitting is missing?
a. Look for other same item and size of fittings with barcode.
b.Switch to manual entry mode at welding unit which allow user to manually input the fusion parameters indicate at the fitting.
What should be carry on, if faced power interruption during the fusion process?
Allow the fitting to fully cooled and repeat the fusion steps by scanning the barcode again. The fusion shall end with the fusion indicators raised.
Why should the surface of the pipe need to fully scrape and clean before fusion being make?
The main reason for scraping is to remove dirt/contamination and reveal a new material surface for effective welding. Dirt acts as a barrier for welding and therefore cleanliness is critical.
All welding surfaces should be scraped immediately prior to welding and should not be touched.
Grease from fingers can act as a barrier to welding. The weld surface before scraping may be cleaned with acetone using a lint free cloth to remove oil/grease. A clean cloth must be used for each weld area.