Our site uses cookies necessary for its proper functioning. To improve your experience, other cookies may be used: you can choose to disable them. This can be changed at any time via the Cookies link at the bottom of the page.


Pent study of cross-linked polyethylene pipe resins

 

Papers

Plastic Pipes Conference Association # 2016 Berlin

Carl F. Baker

The performance of HDPE resins with regards to slow crack growth has increased dramatically over the past two decades. The most common test method for pipe products is ASTM F1473, Standard test Method for Notch Tensile Test to measure the resistance to Slow Crack Growth of Polyethylene Pipes and Resins (PENT). Results are reported as hours to failure. Failure time has increased from a few hundred hours to over 50,000 hours in some cases. Crosslinked polyethylene (PEX) is known to have very high slow crack growth resistance as a result of crosslinking. Unfortunately the methods used to measure the slow crack growth resistance of PEX are different than those used for standard polyethylene (PE) pipe grades. This study reports PENT data for PEX pipe resins, which allows a more direct comparison of the slow crack growth properties of crosslinked PE pipe grades with standard PE pipe grades.

Crosslinked Polyethylene (PEX) pipe and tube are being used globally for potable water plumbing systems, industrial piping systems, radiant heating systems, etc., successfully. PEX materials are generally believed to have very good slow crack growth properties and some would argue that they are immune to slow crack growth. In general, the three common methods of crosslinking, peroxide, silane grafted, and radiation, are treated equally in the standards with regard to physical and mechanical properties. Most PEX standards include some sort of notched pipe test to demonstrate adequate resistance to crack propagation when a defect (notch) is present. However, there is little slow crack growth data available for PEX materials in a form that can be directly related to other materials. This paper will present PENT data for PEX pipe resins. The methodology used to prepare the samples is critical to successful PENT testing of PEX materials and this will be discussed. The data presented will include multiple temperatures and stresses along with failure mode analysis for each resin.

Related keywords : PENT, PEX, Crosslinked, SCG, Slow Crack Growth.
Please note that the whole article content is available on PPCA website only :

Related papers

2023 Lake Buena Vista : A NEW GENERATION OF HIGH PERFORMANCE BIAXIALLY ORIENTED POLYETHYLENE AND POLYPROPYLENE PRESSURE PIPES – AN UPDATE

Author(s) : Ajay Taraiya, Peter Degenhart, Mark Boerakker

In PPXX, a technology was presented for the first time that could bi-axially orient polyolefin pipes. With this technology, it is possible to prepare pipes that have a performance far beyond the standard ones. One approach to achieving this performance is via a continuous in-line process. To optimize the in-line...

2023 Lake Buena Vista : A SUCCESS STORY: NEW TESTING ALTERNATIVES FOR SPANISH AND LATAM PE100RC PIPE MANUFACTURERS

Author(s) : Federico Muñoz

Following the recent approval of European Standards series EN 1555 for Polyethylene piping systems for the supply of gaseous fuels which introduces the PE100RC, a new material with enhanced resistance to Slow Crack Growth (SCG) and anticipating the imminent revision of European Standard series EN 12201 for...

2023 Lake Buena Vista : ALTERNATIVE SLOW CRACK GROWTH TEST FOR THE HDPE CONDUIT INDUSTRY: CORRELATION BETWEEN ESCR AND NCLS

Author(s) : Kevin Copher, Patrick Vibien

High Density Polyethylene (HDPE) conduit is a durable product designed to protect cables for multiple generations buried underground or encased in concrete. Conduit is subject to coiling stresses, installation stresses and in-service stresses, such as those generated from installed curvature, soil loading, or rock...

2023 Lake Buena Vista : CLOSING THE LOOP FOR PEX PIPE IN PRACTICE THROUGH ADVANCED RECYCLING

Author(s) : Robin Bresser, Ilari Aho, Shima Holder, Tijana Duric, Kaisa Suvilampi

Through innovation and experience, PEX pipe solutions have been enabling comfortable heating and safe plumbing with a successful 50-year track record. They are an important facilitator of the green energy transition and the ambitious climate targets of, for example, the European Union (EU) Green Deal by enabling...

2023 Lake Buena Vista : DEVELOPMENT OF A NEW QUALITY CONTROL TEST METHOD TO ASSESS THE STRESS CRACK RESISTANCE OF HDPE

Author(s) : Dr. Michael Pluimer, Sara Stone

The Notched Constant Ligament Stress test (NCLS test, ASTM F2136)[1] is a test method that measures the slow crack growth in High Density Polyethylene. The NCLS test requires a notch on all test specimens to act as a stress concentration at that point so crack propagation can be easily predicted and studied. In...

2023 Lake Buena Vista : DRIVING TOWARDS A CIRCULAR ECONOMYEVALUATION OF PEX RECYCLING

Author(s) : Jacob John, Suresh Shenoy, Patrik Roseen

Cross-linked polyethylene (PEX) pipes continue to gain popularity in plumbing and indoor climate applications around the globe. This study focuses on increasing the sustainability of PEX pipes by utilizing recycled PEX and production waste streams into PEX production. Different methods available for recycling and the...

2023 Lake Buena Vista : EFFECT OF NOTCH RADIUS ON NOTCHED PIPE FAILURE TIME

Author(s) : Aisha Khaleel, Suleyman Deveci, Sulistiyanto Nugroho, Fatima AlHameli

The use of polyethylene pipes in transportation networks of pressurized water and gas have shown superb performance over the history. High density, high-molecular-weight, and bi-modal polyethylene materials, known as PE80, PE100 and PE100RC, have successfully served the market for many years in standard applications....

2023 Lake Buena Vista : EFFECT OF POLYPROPYLENE (PP) POST-CONSUMER RECYCLATE ON THE SLOW CRACK GROWTH RESISTANCE OF A VIRGIN PP PIPE MATERIAL

Author(s) : Jessica Hinczica, Mario Messiha, Florian Arbeiter, Gerald Pinter

In Europe, only 1.8 million tons of recycled material is processed in new products within the building and construction sector [1]. Recyclates and blends of recyclates with virgin materials are already used for different products in the plastic pipe industry, such as cable trays, or storm water management...

2023 Lake Buena Vista : EFFECTS OF POLYMER DESIGN PARAMETERS ON THE SLOW CRACK GROWTH RESISTANCE BASED ON CRACKED ROUND BAR

Author(s) : Jiyong Park, JaeHyuck Han, YoungGu Kim, Eunjin Park

This study investigates the influence of various parameters on polymer design to determine the slow crack growth. HDPE(High Density Polyethylene) materials with different molecular weight distribution and comonomer content for PE100-RC pipe were investigated with cracked round bar test. The cracked round bar test...

2023 Lake Buena Vista : ESTABLISHING REQUIREMENTS FOR RECYCLED HDPE IN HDPE CONDUIT

Author(s) : Michael Pluimer, Christian Herrild, Patrick Vibien

With enhanced interest in a circular economy and the potential use of recycled HDPE within HDPE conduit, a research project was undertaken to investigate the necessary technical requirements when using recycled HDPE. High Density Polyethylene (HDPE) conduit is a durable product designed to protect cables...

2023 Lake Buena Vista : FROM FISHING NETS TO PLASTIC PIPES: NEW CHALLENGES FOR RECYCLED POLYETHYLENE FLOWS IN A CIRCULAR ECONOMY

Author(s) : Rafael A. García-Muñoz, Rafael Juan, Mónica de la Cruz, Beatriz Paredes, Carlos Domínguez

Plastics are widely used in various industries, resulting in the generation of significant amounts of plastic waste, which causes environmental and economic problems. Although mechanical recycling is the most commonly employed technology, the resulting recyclates often suffer from degradation and contamination. This...

2023 Lake Buena Vista : HOW TO CONTROL CRACKS IN PIPES TO GUARANTEE A SAFE OPERATION

Author(s) : Gerald Pinter, Lukas Travnicek, Johannes Wiener, Jan Poduska, Florian Arbeiter, Pavel Hutar

Crack initiation and subsequent crack growth are known to be the key factors which determine the final lifetime of a polymeric pipe. Subsequently, exact knowledge regarding the crack growth behavior is a key issue to guarantee safe operation. Furthermore, novel concepts are needed to satisfy increasing demands, for...

2023 Lake Buena Vista : INFLUENCING FACTORS OF CRACKED ROUND BAR TEST

Author(s) : Yanlei Hu, Jin Sun

Slow crack growth is the main reason for brittle failure of polyethylene pipes. At present, the traditional slow crack growth test generally has many problems, such as too long test time, using chemical reagents that pollute the environment, poor reproducibility, etc., which limit the accurate evaluation of the slow...

2023 Lake Buena Vista : LONG-TERM PERFORMANCE IN PE100 AND PE100RC RESINS: DOES THE COMONOMER LENGTH MATTER?

Author(s) : Carlos Domínguez, Predrag Micic, Rafael Juan, Nuria Robledo, Rafael A. García-Muñoz

Slow Crack Growth (SCG) resistance is the main property that must be controlled for assessing the long-term performance on polyethylene resins used for pipe application. The latest generation of bimodal and multimodal ethylene-α-olefin copolymers with exceptional balance of mechanical properties and processability...

2023 Lake Buena Vista : THE QUALITY OF OLD AND NEW PE PIPES USING THE PENT AND CPENT TEST

Author(s) : Roland Valk

To gain an insight into the residual quality of first-generation polyethylene (PE) pipes used in the Dutch gas distribution grid, pipe segments from all over the Netherlands were excavated by the Dutch Distribution System Operators (DSOs) and tested by Kiwa Technology. The residual quality was determined by...

2023 Lake Buena Vista : WHAT NEEDS TO BE UNDERSTOOD TO USE RECYCLATES IN PLASTIC PIPES: THE INFLUENCE OF IMPURITIES ON LONG-TERM PROPERTIES

Author(s) : Mario Messiha, Jessica Hinczica, Márton Bredàcs, Alwin Huisjes, Florian Arbeiter, Gerald Pinter

BSTRACT Engineering structures, such as operating plastic pipes, are often submitted to unexpected influences that may shorten their lifetime. An increasing understanding about the processes that govern these sudden failures has been attained in the last decades. This has led to a remarkable improvement of pipe...

2021 Amsterdam : A NEW GENERATION OF HIGH PERFORMANCE BIAXIALLY ORIENTED POLYETHYLENE AND POLYPROPYLENE PRESSURE PIPES

Author(s) : A. Taraiya, P. Degenhart, M. Soliman, M. Boerakker, R. Handstanger, R. Kleppinger

Since the introduction of polyolefins for pressure pipes, continuous improvements have been made to meet ever-higher demands on their performance and to expand their application window beyond their original scope, mostly based on new resin formulations. Today, we also continue to push the limit to provide better...

2021 Amsterdam : ALLOWABLE SCRATCH DEPTH HISTORY & RECOMMENDATIONS FOR PE PRESSURE PIPE

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...

2021 Amsterdam : EFFECT OF CHLORINATED WATER ON THE FATIGUE CRACK GROWTH RESISTANCE OF POLYETHYLENE COMPOUNDS WITH RECYCLATE CONTENT FOR PIPE APPLICATIONS

Author(s) : Paul J. Freudenthaler, Joerg Fischer, Mathias Eder, Reinhold W. Lang

For controlled water disinfection, typically chlorine is used and preliminary studies demonstrate its aging and crack growth acceleration effects on polyolefin pipe materials [1, 2]. Although the use of recycled plastics is not prohibited in some ISO standards for polyolefin piping systems [3–5], only small amounts...

2021 Amsterdam : EVALUATION OF MECHANICAL PROPERTIES AND LONG- TERM DURABILITY OF AGED POLYETHYLENE PIPES FOR GAS DISTRIBUTION

Author(s) : Shuhei Nishida, Shintaro Iwasaki, Hidefumi Yamanaka, Takahiro Kasatani

Polyethylene pipelines have been used for natural gas service applications for over 40 years in Japan. It is thought that they will continue to be used widely for many years. Therefore, it is important to confirm the conditions of the existing pipelines being used for the long term. In this study, polyethylene pipes...

Members of the Association

BOREALISBOROUGEFormosa Plastics CorporationHanwha TotalEnergiesINEOS O&PIRPCKorea Petrochemical IND. Co., LTD (KPIC)LyondellBasellORLEN UnipetrolPetroChina Dushanzi Petrochemical CompanyPRIME POLYMERSABICSCG Chemicals & Thai PolyethyleneSinopecTASNEE