Lever, Palermo, Wright, Oliphant
Material Science # 2006 Washington DC
The piping industry has a need for a well-founded methodology to predict lifetime of pipeline components subject to stress concentration. Another useful tool would be a method to assess the impact of manufacturing processes on the slow crack growth (SCG) properties of a resin that can be used for process control in a manufacturing facility. In this paper we will propose an innovative methodology for predicting the time to failure of molded fittings due to the SCG failure mechanism that can also be used for optimized manufacturing process control. This method initially utilizes the well-known Rate Process Method (RPM) analysis of molded fitting assemblies for lifetime prediction. Stresses in the molded fittings are determined by finite element analysis. The method also utilizes the new Notch Ring Test (NRT) with rings cut from the molded fittings for assessing the impact of process conditions on SCG characteristics of PE fittings. Stresses in the NRT rings are also determined by finite element analysis. With these NRT data, the fitting manufacturer can develop a reliable method for process control by determining the effect of process variables on SCG performance. Correlation of the RPM data with the NRT data using the same molded fittings will provide an NRT process control method that has been validated by the RPM lifetime prediction method. By fully characterizing the SCG properties of the particular material used and fully characterizing the stress concentrations, a rational methodology for lifetime prediction is then available to the pipeline engineer, and a rational methodology for process control is available to the fitting manufacturer. This methodology can then be incorporated into national and international standards.
Related papers
Author(s) : Chris Ampfer, Gene Palermo, Ernest & Oren Lever
This paper looks at the origin of the 10% allowable scratch depth rule for polyethylene (PE) pressure pipe developed in 1971 and research that has been performed over the years since its inception to determine the validity of this rule. The 10% rule has been used by natural gas pipeline operators since the 1970’s to...
Author(s) : Ernest Lever
Six different polyethylene materials were tested using Cyclic Pressure Fatigue (CPF) as the accelerating process to correlate the results to conventional long-term hydrostatic test results that were previously developed as part of the material qualification process. The designation of the materials was unknown to the...
Author(s) : Gerry Groen, Ernest Lever, Oren Lever
A design justification for reinforcement of fabricated Polyethylene elbows is presented. The acceptance criteria is that the average stress in the mitered wall of fabricated elbow shall not exceed the hoop stress in the matching pipe. ASTM and ISO standards have established requirements for the geometry, production...
Author(s) : Ernest Lever, Yongming Liu, Yiming Deng
This collaborative program will provide an integrated set of quantitative tools that will provide a structured approach to reducing operational risk in vintage plastic distribution systems susceptible to Slow Crack Growth failures. A novel endoscopic structured light scanning tool will be developed and prototyped for...
Author(s) : Ernest Lever, Karen Crippen
The objective of this project was to develop methods to be used by any plastic testing laboratory to quantify the effects of hydrocarbon permeation on: 1) the fusibility of plastic pipe; 2) the life expectancy of existing fused joints that have been subjected to hydrocarbon permeation; 3) the Hydrostatic Design Basis...
Author(s) : Dr. Ken Oliphant, William Luff, Dr. Peter Angelo, Patrick Vibien
Managing aging pipeline infrastructure is an important part of overall pipeline risk management. The critical risk management questions for an aging infrastructure are: how quickly should replacement occur and what parts of the system should be prioritized for replacement. To answer these questions it is necessary to...
Author(s) : Dr. Ken Oliphant, Patrick Vibien, Dr. Michael Conrad, Sarah Chung
A new methodology has been developed to validate the performance of polyethylene piping materials in potable water applications. The methodology is based on several research programs which examined a standardized accelerated test methodology (ASTM F2263 Standard Test Method for Evaluating the Oxidative Resistance of...
Author(s) : Ernest Lever
The Popelar bidirectional shift factors have been now been used about a quarter century to great effect. The question has been raised as to whether the shift factors are applicable to modern materials. GTI has been using rheological principles and Dynamic Thermo Mechanical Analysis (DTMA) to routinely develop...
Author(s) : Dr. Gene Palermo, Dr. Dane Chang, Dr. Jimmy Zhou
The scope of this paper is to provide information for the plastic piping industry on a test methodology that could determine the design life of heat fusion fittings and joints at the end user field conditions of operating stress, operating temperature and desired design life. This methodology is useful not only for...
Author(s) : Dr. Ken Oliphant, Patrick Vibien
New and formal approaches to Asset Management (AM), such as the PAS-55 and ISO 55000 Asset Management standards have been developed over the past decade. These AM standards can be applied to pipelines and cover all stages of a pipeline's lifecycle - acquisition, operation, maintenance and renewal/disposal and provide...
Author(s) : Ernest Lever
Aldyl A piping systems are closing in on fifty years of service in North America. Several North American gas utilities are assessing the remaining lifetime expectancy of their Aldyl A piping systems and preparing replacement programs. GTI has been actively involved in multiple research efforts related to Aldyl A...
Author(s) : Karen Crippen, Ernest Lever
DOT/PHMSA held a Government/Industry Pipeline R&D Forum on July 18-19, 2012. Five working groups met to discuss key pipeline technical challenges facing industry and government. The Design/Materials/Welding-Joining & Valves working group identified the effects of hydrocarbon permeation on plastic pipe strength and...
Author(s) : Rob. J. Fox, Dr. Gene Palermo
CSA Z662 is the Standard for the use of plastic pipe in Canadian oil and gas pipeline systems. This paper will give an overview of the recently approved revisions to CSA Z662-11 “Oil and Gas Pipeline Systems”, which will be published next year. These revisions include the following : - RCP Requirements for PE pipe, -...
Author(s) : Dr. Gene Palermo
The scope of this paper is to clarify the various pipe material designation codes and other terms (PE 4710, PE 4710 PLUS, PE 100, PE 100 RC and PE 100+) that are used in the piping industry for high density polyethylene (HDPE) materials. These are the benchmark “high performance” HDPE materials used worldwide for a...
Author(s) : K.Oliphant
Polyethylene (PE) piping materials have been used in potable water applications for more than 50 years with considerable success and have enjoyed a consistently high satisfaction rating from Water Utilities. Since the introduction of these first materials, material performance has evolved significantly. To demonstrate...
Author(s) : S. Chung, M. Conrad, S. Lee, K. Oliphant, M. Wang
ASTM F2023 and ASTM F2263 have been used to evaluate the oxidative resistance of plastic piping materials to potable water. As a potential method to accelerate this testing, the use of internally notched pipe has been investigated and preliminary research has shown that the method appears to be able to generate the...
Author(s) : G.Palermo
Manitoba Hydro is the electrical and natural gas utility for the province of Manitoba. A project to expand the existing natural gas system was initiated in 2005 which required the installation of a 29 kilometer (18 miles) main to connect a new town to the existing system. Project financial restrictions could not be...
Author(s) : Chung, Li, Oliphant, Vibien, Rozental-Evesque, Rabaud
Plastic piping materials confer many advantages for applications in Potable Water transportation. Considerable research has been conducted to develop methodologies for ensuring performance in these applications for service lifetimes that target an excess of 100 years. A key component of these accelerated methodologies...
Author(s) : Chung, Oliphant, Vibien, Zhang
Disinfectants are commonly added to potable water to control bacteria, viruses, protozoa, algae and fungi which can potentially lead to waterborne diseases. The three most common disinfectants used for maintaining a disinfectant residual in North America are chlorine, chloramines and chlorine dioxide. While these...
Author(s) : Kosari, Oliphant, Vibien,
The Small Scale Steady State (S4) Rapid Crack Propagation (RCP) test methodology has proven to be an effective tool in assessing resistance to rapid crack propagation. At the same time, an evolution in polyethylene material performance has occurred that has produced materials with increasingly higher resistance to...
Members of the Association
