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.”
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.
03 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.
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.
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
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 existing pipe using mechanical fittings, electrofusion couplings, or flanged connections. Refer to the PPI Handbook on HDPE Pipe Repair and Maintenance
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.
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.
There are no hazardous fumes associated with the cutting of HDPE pipe.
No. The Hazen Williams C factor of 155 was determined with pipe that was fused together and thus contained inner fusion beads.
The equipment is readily available through distributors such as Hürner
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.
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.
No. Our pipes are made against European standards, such as EN 12201 and EN 1555, and not against American ASTM standards.
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.
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
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.
Welders must hold appropriate certificates recognized 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.
23 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.
Pipe support rollers.
Indelible marker pens.
Ground sheets or base boards.
Clean clothes to wipe the pipes before trimming.
Spirit Level to ensure machine is level.
Bead size measurement tool.
24 How to determine the quality of butt fusion joint? The following requirement shall be meet for a quality joint.
No dirt contamination.
25 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
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.
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.
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.
Generally, the strain capacity of polyethylene is sufficiently safe for a bend ratio of 20. However, there is another limit to bending. Longitudinal bending induces ovality in the ring direction of the pipe thus reducing the resistance to kinking (local buckling).
Polyethylene (PE) is a soft polymer found in the two main types LDPE & HDPE. At higher temperatures, this plastic loses its rigidity and begins to melt. LDPE will already begin melting at 105°C and HDPE will begin melting at 125°C.