Peelable Polyethylene Pipe For Gas Piping Applications Dr. Gene Palermo – P Cubed Consulting Jeremy Bowman – Radius

1. Peelable Polyethylene Pipe For Gas Piping Applications Dr. Gene Palermo – P Cubed Consulting Jeremy Bowman – Radius Systems Ltd.

2. Radius Systems Ltd – Formerly Ltd June 2008 purchased by 3i • 2008 turnover > $200M • Manufacture • PE and PVC pipes • Peelable pipe (PE/PP) • Electrofusion Fittings • UK PE Market • > 80% gas • ~ 40% clean water Key focus on innovation Only the name has changed

3. Strength & UV Benefits Provided by Skinned (Peelable) Pipe • CONTENTS • Pipe Structure • 2. PE80 strength v PE100 • 3. Studies on Peelable Pipe Strength • 4. Peelable Pipe UV Stability • 5. Electrofusion Jointing • 6. Conclusions

4. Pipe Structure; Skin • Sacrificial & peelable skin • Skin is ‘extra’ material • Skin thickness • Typically 0.8mm (0.031”) • 1.5mm (0.059”) option • Skin colour denotes utility • Stripes advise peelable skin (EF joining) and SDR of PE pipe

5. Pipe Structure; Core PE ‘Pipe’ • Black PE 100 or PE 4710 core pipe • Natural PE core pipe available • Dimensions of the core PE pipe are the same as solid wall PE pipes • Outside diameter • Wall thickness • Thus meet D 2513 requirements • Pipe pressure rating • From core PE pipe only • Skin neglected in pressure rating

6. Strength & UV Benefits Provided by Skinned Pipe • CONTENTS • PE 80 strength vs PE 100 (PE 2708 or PE 4710) • What pressure rating do PE80 and PE100 pipes have for gas pipe networks

7. PE PIPES; Regression Curves © Radius Systems 2008

8. 20 20°C Regression Curve Pipe HoopStress (MPa) 50 years 12.4 10 PE100 LPL between 10.0 & 12.49 MPa PE80 LPL between 8.0 & 9.9 MPa 5 2 1 102 104 106 Time (hrs) PE GAS PIPES; Ductile Strength 100 hrs © Radius Systems 2008

9. PE MATERIALS; Density, Modulus & Strength PE100 resins, compared to PE80 resins, are of higher density, and are both stiffer and stronger

10. PE MATERIALS; Pipe pressure Rating (bars) PE100 peelable pipes, SDR21, are equivalent to SDR17.6 PE80 pipes on the ductile strength.

11. Strength & UV Benefits Provided by Skinned Pipe • CONTENTS • 3. Studies on Peelable Strength • Identify the contribution made by the PP skin to the 50 year 20°C strength of the pipe. • Use that strength to identify the actual safety factor for skinned (peelable) pipe

12. Pipe Strength Study; Test Samples © Radius Systems 2008

13. Pipe Strength (bar); Plain PE100 Pipe Extrapolated 50 year strength © Radius Systems 2008

14. Pipe Strength (bar); PE100 Pipe + 1.5mm Skin Extrapolated 50 year strength © Radius Systems 2008

15. Pipe Strength; Hoop Stress and Pressure © Radius Systems 2008

16. Pipe Strength; Accounting for DR Variation © Radius Systems 2008

17. Pipe Strength (bar); Measured & Equivalent © Radius Systems 2008

18. Pipe Strength (bar); Safety Factors Greater safety factor means less affected by external scratches that occurduring installation of PE gas pipe, such as HDD or insertion. © Radius Systems 2008

19. Strength & UV Benefits Provided by Skinned Pipe • CONTENTS • 4. Peelable Pipe UV Stability • When exposed to direct sunlight, what level of extra protection does the skin provide for the core pipe?

20. Pipe subjected to Arizona Desert sun Pipe is shielded from the sun, but has to sustain the desert heat Pipe UV Stability; Sample Exposure • Pipe is not rotated • ½ of pipe sees the sun, ½ does not • Pipe measured to receive • 1 GJ.m-2 • 3 GJ.m-2 • 10 GJ.m-2

21. Oxidation Induction Time; Sample Location Arizona desert sun acts on the top of the pipe Samples 1 – 5 and 20 – 24 Numbers indicate the location of the OIT sample around the circumference . . 24 23 22 21 20 19 OIT at 210°C Shielded from direct sun-light Samples 8 - 17 18 17 16 15 14 13

22. OIT; Plain PE100 pipes, no skin Pipe as extruded no sun exposure 3 GJ.m-2 exposure 10 GJ.m-2 exposure

23. OIT; 10GJ.m-2 on ProFuse & Solid Wall Pipe Shielded from direct sun-light OIT values of the core PE pipe after removing the skin Solid wall PE100 pipe In the Arizona sun In the Arizona sun

24. Strength & UV Benefits Provided by Skinned Pipe CONTENTS 5. Electrofusion Jointing Does the retained stabilisation of skinned pipes, influence the quality of electrofusion joints formed with skinned pipes ?

25. Electrofusion Jointing; Sample location . . Pipe subjected to sun is on the top . Subjected to the sun; samples 4, 5 and 6 . . . . . . Shielded from the sun samples 1, 2 and 3 . .

26. 3GJ.m-2 aged Plain Pipe; EF joint, no scraping Pipes prepared for EF joining by cleaning with alcohol wipes only Load (N) 654321 In the sun In the shade © Radius Systems 2008

27. 10GJ.m-2 aged Peelable Pipe; Peel skin & EF joint * The skin thickness was 0.4mm, ½ the normal 654321 In the sun In the shade © Radius Systems 2008

28. Strength & UV Benefits Provided by Skinned Pipe • CONTENTS • Pipe Structure • PE80 strength v PE100 • Studies on ProFuse Strength • ProFuse UV Stability • Electrofusion Jointing • Conclusions

29. Strength & UV Benefits Provided by Skinned Pipe; Conclusions For skinned pipes with a core PE pipe to EN/ISO (ASTM) dimensions Pressure strength of skinned pipe (peelable) is raised by 14% The safety factor for gas pipes is then greater than 2.3 This improved pressure capability, which is a function of skin thickness, provides additional safety from external scratches when installed. • Fully stabilised control (plain) pipe shows: • a major decrease in OIT in the sun at doses of 3GJ.m-2. • a significant loss in OIT in the shade at doses of 10GJ.m-2 • The presence of even a thin skin (0.4mm) fully protects the core PE pipe, both in the sun and in the shade, at 10GJ.m-2 Electrofusion joints, made to 10GJ.m-2 aged peelable pipe where the skin was peeled off, were ductile for all areas of the pipe © Radius Systems 2008

30. Polyethylene Pipes; Water & Gas This the direction the European utility sector is going! © Radius Systems 2008