Conduit shall be made from highdensity polyethylene hdpe. Effects of recycled hdpe and nanoclay on stress cracking of hdpe by correlating j. Resistance to this mode of failure can be best gauged through constanttensileload testing, while taking into account the differences in. Environment stress cracking of hdpe products is quite common due to its semi crystalline nature which gets attacked due to chemicals present in the environment. It has been known for quite some time that the addition of an elastomeric material to polyethylene can improve its resistance to environmental stress. Evaluate the longterm stress crack resistance of corrugated hdpe pipes y. Corrugated high density polyethylene hdpe pipe 36 in. A slightly less crystalline hdpe will have better crack resistance, and density is a direct measure of crystallinity. However, the designing or specifying engineer should be. This stress relaxation allows testing to run without failure for very long periods 1,500 hours. Stress crack article about stress crack by the free dictionary. Environmental stress crack resistance, astm d1693 cond. High and low temperature performance non corrosive lightweight flexible tough and abrasion resistant environmental stress resistance chemical and soil resistant slow.
Hdpe conduit will ovalize when it is coiled, and after a period of time,will set into the coiled state. The pipe has some excellent features such as low temperature impact resistance, reliable connection, good stress crack resistance, good chemical resistance, good wear resistance, long using life, etc. The material requirements for pe conduit shall be classified in accordance with astm standard d 3350 standard specification for polyethylene plastic pipe and fittings materials. B 10% lgepal environmental stress crack resistance, astm d1693 cond. When a plastic part is under mechanical stress it can result in crack formation and propagation, eventually leading to part failure. Standard specification for solid wall high density polyethylene hdpe conduit based on controlled outside diameter astm d 2412. According to astm d 883, stress crack is defined as an external or internal crack in a plastic caused by tensile stresses less than its shorttime mechanical strength.
Astm d 1693 test method for environmental stresscracking of ethylene plastics. Astm d 3350 defines important physical properties of hdpe materials into ranges, or cell classes, so that each property can be defined. The primary physical property advantages of hdpe conduit are flexibility, ductility and chemical resistance. Hdpe pipeconduit for fiber cable optic protection, find complete details about hdpe pipeconduit for fiber cable optic protection,hdpe pipe for fiber optic,hdpe cable conduit,hdpe pipe for cable optic from plastic tubes supplier or manufacturerluoyang max pipe industry co. Stress cracking sc is recognized as one of the major concerns for high density. Stress crack article about stress crack by the free. It is well known from the pipe and cable insulation industries that pe can stress crack over long periods of time.
One such performance criteria is environmental stress crack resistance escr. Innerducts are used primarily to provide multiple raceways within an existing conduit system. Escr in hdpe products and how resin properties influence escr. Jm eagle hdpe communication duct is available in 3. Centennial plastics potable water pipe is certified to nsf international standard 14 and awwa c901 and c906, cc3 classification. The inherent properties of hdpe such as chemical resistance and stress crack resistance are wellsuited for. Carlon electrical listed high density polyethylene hdpe. When compared to other materials, hdpe has many features which make it superior. The nature of polyethylene pipe failure plasticstoday. Is high stress crack resistant and has a 30% lower coefficient of friction than pvc. Thus, if conditions are unfavorable, various oils or even common household cleaning agents may cause a polyethylene bag, pipe, tank, drum or bottle to crack and. High and low temperature performance non corrosive lightweight flexible tough and abrasion resistant environmental stress resistance chemical and soil resistant slow crack. North coast conduit smoothwall is manufactured from high density polyethylene hdpe and is intended for use in underground, aerial, and innerduct applications. Tel 610 522 drexel fax 610 5228441 geosynthetic institute.
Strain hardening modulus as a measure of environmental. Pe100rc, hscr, stress, asia, middle east the rapid development of asia and the. The scr tests were performed on the finished pipe at the liner and junction locations. Pdf factors affecting stress crack resistance of corrugated. While this can occur under high stress conditions, one of the most common forms of failure for plastic components is low stress failure. Environmental stress crack resistance service temperatures up to 60c 140f is highly resistant to a wide variety of rather reactive cracking of escr is carried out on molded specimens 18 in. The notched constant ligament stress ncls test astm 2163 was used for the pipe liner assessment. The conduit may be direct buried, encased in concrete and used as innerducts. Stress crack resistance sometimes referred to as slow crack growth resistance.
A residual curve is normal for all coiled hdpe duct products. Cenduct hdpe communications duct pipe centennial plastics. Environmental stress crack resistance of polyethylene. Smoothwall offers superior protection and serves as an ideal raceway for future cable expansion. Unipol pe conduit pipe products cover various telecommunication cables, and electrical utility uses, including electrical service conduit, insulation sleeves, jelly filled cables and coaxial cable conduit. Products carrying the nsf14 identification are required to be tested as to raw material classification, sustained pressure, burst pressure, environmental stress crack resistance, dimensions and workmanship.
D638 type iv % 500 % 500 flexural modulus d3350 d790 psi. Mdpe exhibited excellent scg and stress crack resistance, and dominated pe pipe manufacture for 30 years until the development of bimodal hdpe pe100. Unipol pe conduit pipe delivers excellent flexibility, high escr, and long life making these grades ideally suited for this application. Creek plastics llc produces many standard types and sizes of highdensity polyethylene hdpe pipe and conduit to meet your specifications.
The 100year stress crack resistance scr of corrugated hdpe pipes was evaluated using a. Hdpe corrugated pipe service life corrugated stress. The hdpe shall meet or exceed the properties listed in astm d3350 for cell classification 334470 c black, minimum 2% carbon black or e color with uv stabilizer. Resistance to this mode of failure can be best gauged through constanttensileload testing, while taking into account the differences in yield point among various polyethylenes. The hdpe shall meet or exceed the properties listed in astm d. The aashto document explains that hdpe conduit is a protective pathway for telecommunications and power cables used throughout the infrastructure. In the current aashto m294 specification for hdpe corrugated pipe, the stress crack resistance scr property is determined based on the performance of virgin pipe resins. Astm test description values hdpe d1505 density gcm3. Consider using an internal z or h divider during this season.
Experimental study of stress cracking in high density polyethylene pipes a thesis submitted to the faculty of drexel university by jingyu zhang. Fact there are no aashto accepted 100year longterm material properties for m294 pipe. Carlon power cable in duct purchase carlon conduit. The bent strip test is a constant strain test, but polyethylene relaxes when strained. Highdensity polyethylene pipe with high resistance to slow crack growth. Slow crack growth f1473 environmental stress cracking d1693 impact resistance d2444. Environmental stress crack resistance lyondellbasell. Pe100 grades pe100rc which have a much higher resistance to scg. Basic understanding of stress cracking in hdpe products. Other physical attributes critical to the performance of hdpe conduit are tensile strength and stress crack resistance. Highdensity polyethylene hdpe conduit 1 scope this material specification provides guidelines for specifying hdpe conduit. Stress crack resistance of corrugated hdpe pipes in. The inherent properties of hdpe such as chemical resistance and stress crack resistance are wellsuited for infrastructure systems since these require long service life. Polyethylene pe has revolutionized lowpressure pipe system design.
Test for external loading properties of plastics pipe by parallel plate loading astm d 2444. This study investigates production of crosslinked polyethylene pex pipes. Hdpe pipeconduit for fiber cable optic protection buy hdpe. Strain hardening modulus as a measure of environmental stress.
Hdpe grades are used in a variety of processing techniques such as extrusion, extrusion blow molding, injection and rotational molding. Enhancing the environmental stress crack resistance of hdpe. Jan 18, 2011 hence, an important design factor for pe pipes became commonly known as environmental stress cracking resistance escr, which led to the development of mdpe. Thus, it is reasonable to conclude that hdpe pipe manufactured today may have an even shorter service life than that produced 20 years ago. These are conditions which can lead to the initiation of cracks in the pipe wall and. North coast conduit began manufacturing hdpe innerduct and conduit in 2010 as an alternative source to the ever decreasing choice of suppliers. D1693 environmental stress crack resistance condition b,f. Challenges still remain, however, with respect to the stress crack resistance scr of hdpe pipe over its design life when recycled hdpe is blended with the pristine resin. Astm d 2444 test method for impact resistance of thermoplastic pipe and fittings by means of a tup. Environmental stress crack resistance b f20192 hours condition c 3or4 astm d 1693 hdb not defined 0,1,2,3,or 4 astm d2837 united poly systems c o n d u i t. Because parts made with vistamaxx enhanced hdpe are tougher than those made with pure hdpe, they are less likely to fail through environmental stress cracking. Environmental stress crack resistance of polyethylene introduction to environmental stress cracking and escr over the past decade, high density polyethylene hdpe materials have improved significantly and now meet more stringent performance standards. Escr problems get more pronounced in the summer, because of several factors related to increased heat and humidity.
Resistance to stress cracking was also critical in order to inhibit crack. The stress cracking is more severe with detergent, bleach, motor oil and some industrial chemical packaging. Minimum required strength mrs this provides longterm strength and creep resistance. Grace hsuan, jy zhang and wk wong department of civil, architectural and environmental engineering, drexel university, philadelphia, usa. Environmental stress crack resistance 5000 hour 5000 hour condition c. Straight lengths of conduit shall have ovality of 5% or less. Hdpe solid wall conduit model specification power and communications conduit and casing. Jm eagles highdensity polyethylene communication duct pipe is suitable for telecom and fiberoptic, nonpressurized or potable applications. Experimental study of stress cracking in high density.
However, the designing or specifying engineer should be aware that not all pe materials deliver the same level of performance in these areas, and it is critical to ensure that the material meets all the demands of the installation and service conditions. Technical note stress crack resistance for geomembrane products the stress crack resistance scr of polyethylene pe geomembranes has been the subject of study since the introduction of the materials over 20 years ago. Environmental stress cracking resistance of polyethylene. Technical note stress crack resistance for geomembrane products.
Corrugated highdensity polyethylene hdpe pipe 36 in. Experimental study of stress cracking in high density polyethylene. Offers optimal cable protection from rock and root impingement. Get a handle on stresscracking in hdpe bottles one of the first applications for blow molded hdpe bottles was the replacement of glass for bleach packaging. The introduction of high stress crack resistant pe100 and its.
Environmental stress cracking in polyethylene takes place because of interlamellar failure, which in turn is caused by relaxation of tie molecules. Astm d 3350 defines important physical properties of hdpe materials into ranges, or. Lightweight and flexible long lengths allow for easy installation. Because of north coasts size and attention to quality they offer the best possible value in the industry. The property of environmental stress cracking is a critical performance factor in the polyethylene product areas of rigid and flexible containers, wire and cable insulation and pipe or conduit. This method is used in the united states to test pe pipe. Effects of recycled hdpe and nanoclay on stress cracking of. Environmental stress crack resistance of polyethylene ineos.
The resin properties shall meet or exceed the values listed below for hdpe. Ligamentstress ncls test to determine slowcrack growth resistance of. Teels highdensity polyethylene conduit pipe is made from hdpe material that meets or exceeds cell classification and performance. Creek plastics llc produces many standard types and sizes of high density polyethylene hdpe pipe and conduit to meet your specifications. For instance, plastics are being used extensively in fluid flow applications, such as piping for gas distribution and tubing for water transfer 1. Environmental stress crack resistance of polyethylene today, this test is specified less frequently because it is not as aggressive towards modern resins. Environmental stress crack resistance of polyethylene introduction to environmental stress cracking and escr over the past decade, highdensity polyethylene hdpe materials have improved significantly and now meet more stringent performance standards. Slow crack resistance in polyethylene has been reported extensively in the literature 19,19. High density polyethylene hdpe sheet can be susceptible to a phenomenon known as environmental stress cracking esc. Challenges still remain, however, with respect to the stress crack resistance scr of hdpe pipe over its design life when recycled hdpe is blended with the.
302 256 602 1322 1228 616 845 937 475 1508 1166 272 72 646 935 1440 353 334 188 731 1453 274 388 1017 1157 454 873 296 1505 351 401 1118 1367 1078 1329 778 556 1497 996 1327