Service is the difference MEA Roundtable October 30, 2007

Service is the difference Over the past 30 years, research has better defined how polyethylene pipe materials function as pipes.

Service is the difference Substantial breakthroughs in resin technology have led to higher performing polyethylene resins.

Service is the difference Standards and Regulations did not recognize or allow end users to benefit from these higher performing products.

Service is the difference This has led to industry initiated changes in nomenclature, in standards, and potential changes in DOT regulations to allow end users take full advantage of polyethylene’s capabilities.

Service is the difference Update of changes already implemented or underway in standards and regulations Understand the key parameters in designing PE Pipes for Gas Distribution service Slow Crack Growth Resistance Long Term Pressure Rating Resistance to Rapid Crack

Service is the difference

Standard Specification for Polyethylene Plastics Pipe and Fittings Materials CELL CLASSIFICATION CHANGES APPROVED IN 2005 Policies and Procedures for Developing HDB, PDB, SDB, and MRS Ratings for Thermoplastic Piping Materials or Pipe (2006) MATERIAL DESIGNATION CHANGES APPROVED IN 2006

Service is the difference Standard Specification for Thermoplastic Gas Pressure Pipe, Tubing and Fittings APPROVED AND PUBLISHED IN 2007 DOT continues to reference an older version of D2513, and still requires the old material designations

Service is the difference Polyethylene Designation

Service is the difference Polyethylene Density Slow Crack Growth Design Stress for Water

Service is the difference Polyethylene Density Design Stress for Water

Service is the difference Polyethylene Density Slow Crack Growth Design Stress for Water

Service is the difference Polyethylene Density Design Stress for Water

Service is the difference BEFORE >0.955 >0.947 to >0.940 to >0.925 to or lower ASTM D1505 Natural Density, g/cc AFTER N/A > >0.940 to >0.925 to or lower ASTM D1505 Natural Density, g/cc Cell 5 Cell 4 Cell 3 Cell 2 Cell 1 Test Property SPLIT THE DENSITY CELL CLASSIFICATION

Service is the difference BEFORE >500 - Cell 7 >100>30>10 ASTM F1473 Slow Crack Growth PENT hrs AFTER >100>30>10 ASTM F1473 Slow Crack Growth PENT hrs Cell 6 Cell 5 Cell 4 Test Property Added a higher criteria for slow crack growth resistance

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Plastic Pipe Institute (PPI) revised the service pressure design factor in non-regulated applications for high performing materials Excellent resistance to Slow Crack Growth High statistical confidence limit in data Substantiated linear extrapolation to 50 years Increase design stress for non-regulated applications

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Addition of PE2708, 3710, and 4710 designations approved, and published as D a. Added requirements for the use of Rework to maintain cleanliness. Limited Rework to 30%. In the process of adding information related to rapid crack test data. Removing the MRS annex at AGA’s request.

Service is the difference Changes in the material designations has not changed the DOT design factor AGA (OTD) IDF committee formed to develop a technical basis to justify a 0.4 design factor – AGA, DOT, PPI Manufacturers and GTI participating Phase I to establish performance parameters is complete – Based on similar factors to PPI change – May have an RCP limiting pressure/temperature

Service is the difference Phase II Field Testing completed 7/06 Sidewall Fusion Coiling/Uncoiling Squeeze Off Installation Methods Repair Methods Phase III Waivers at 0.4 design factor pending Prepare DOT Petition

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Main source of material related field failures 3 rd party damage is the largest single cause Caused by low level of external stress over a long period of time Rock impingement Shifting soils Tight bends Main source of material related field failures 3 rd party damage is the largest single cause Caused by low level of external stress over a long period of time Rock impingement Shifting soils Tight bends

Service is the difference ASTM F1473 PENT test Notched tensile testing Simple short term method A good screening tool Not an accurate predictor of service life

Service is the difference Material Testing Lab Bartlesville, OK PENT Testing Equipment

Service is the difference In 1990’s ASTM D2513 required a minimum of 100 hours PENT resistance to slow crack growth. In 2006 PPI defined high performing plastic pipes as having PENT hours > 500 hours.

Service is the difference AT VERY HIGH PENT TEST HOURS, THE TEST NO LONGER PREDICTS FIELD PERFORMANCE Research is underway to develop a better test method to differentiate between the high performing pipe materials.

Service is the difference Samples show a ductile yield – not slow crack growth 'Accelerated Slow Crack Growth Method' Steve Boros, PlasticsPipes XIII, Washington DC, October 2006 Analysis of Ductile and Brittle Failures from Creep Rupture Testing of High-Density Polyethylene (HDPE) Pipes Rajendra Krishnaswamy, PlasticsPipes XIII, Washington DC, October 2006

Service is the difference Material Testing Lab Bartlesville, OK Long Term Pressure Test Equipment

Service is the difference Pressure rating is based on long term testing (over 1 year) at both operating and elevated temperatures Apply a safety design factor to account for uncertainty and risk Pressure = 2 x Stress x Safety Factor \ (DR – 1) = 2 x Hydrostatic Design Basis x Fs ((Outside Diameter \ Wall Thickness) – 1)

Service is the difference 49 CFR 192 currently requires a safety factor of 0.32 Pressure = 2 x Stress x 0.32 \ (DR – 1) = 2 x Hydrostatic Design Basis x 0.32 ((Outside Diameter \ Wall Thickness) – 1) 49 CFR 192 currently requires a safety factor of 0.32 Pressure = 2 x Stress x 0.32 \ (DR – 1) = 2 x Hydrostatic Design Basis x 0.32 ((Outside Diameter \ Wall Thickness) – 1)

Service is the difference Hours Stress Stress testing results of SOME early PE2306 and PE3306 materials 73.4 º F140 º F 176 º F 73.4 º F DOT Operating Stress

Service is the difference 140 deg F 176 deg F HOURS STRESS 73.4 º F Test Data 73.4 º F DOT Operating Stress 140 º F 176 º F Example of High Density High Performing

Service is the difference Research on Polyethylene Pipes has resulted in test methods to better predict the long term performance based on high temperature testing

Service is the difference Waivers are pending, for regulated applications, requesting an increase from 0.32 to 0.40

Service is the difference Also called Rapid Crack Propagation (RCP) if it is under pressure Occurs when a highly localized stress is quickly applied to the pipe Severe Impact Saw Cut pipe with pressure on the end Severe Impact Saw Cut pipe with pressure on the end

Service is the difference Rapid Cracking failures in gas pipes.Rapid Cracking failures are not common in gas pipes. Resistance to Rapid Crack increases Where sizes are smaller Where temperatures are higher Where pressures are lower

Service is the difference Test Method ISO13478 Chill >40ft of pipe to 0 deg C Apply pressure and impact the pipe with a sharpened blade into a preformed notch Successively raise the pressure until the pipe crack propagates

Service is the difference Full Scale Test Facility Gent, Belgium

Service is the difference Test Method ISO13477 Chill ~6ft to 0 deg C Apply pressure and impact the pipe with a razor blade into a preformed notch Successively raise the pressure until the pipe crack propagates Conservative correlation to Full Scale testing

Service is the difference S4 RCP Test Facility Bartlesville, OK

Service is the difference TESTING IDENTIFIES A CRITICAL PRESSURE AND A CRITICAL TEMPERATURE 8” IPS DR11 0º C

Service is the difference Updated ASTM and PPI documents Updated resin nomenclature 3 Key Design parameters Updated ASTM and PPI documents Updated resin nomenclature 3 Key Design parameters Slow Crack Growth - PENT Pressure Rating Rapid Crack Propagation - RCP Slow Crack Growth - PENT Pressure Rating Rapid Crack Propagation - RCP

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