Behavior of High-Density Polyethylene Pipe with Shallow Cover

1998 ◽  
Vol 1624 (1) ◽  
pp. 214-224 ◽  
Author(s):  
B. M. Phares ◽  
T. J. Wipf ◽  
F. W. Klaiber ◽  
R. A. Lohnes
Keyword(s):  
High Density Polyethylene ◽  
Parallel Plate ◽  
Large Diameter ◽  
Field Tests ◽  
High Density ◽  
Concentrated Loads ◽  
Testing Program ◽  
Flexural Testing ◽  
Longitudinal Strength ◽  
Flexural Tests

In this investigation, a testing program was initiated to gain some understanding of the nature of high-density polyethylene (HDPE) as a structural material and as a buried structure. The testing program consisted of a series of parallel plate tests, a sequence of flexural tests, and field tests of buried pipes under varying backfill conditions. Parallel plate tests were conducted in accordance with ASTM D2412. The flexural testing consisted of applying two point loads to simply supported beam specimens. The field tests completed in this investigation were developed to study the response of large-diameter HDPE to concentrated loads under shallow cover. From the testing, it seems that in cases where high longitudinal stresses may be present (concentrated loads with shallow cover, uneven bedding, uplift, etc.) the pipeline designer should consider the longitudinal strength of HDPE pipes in addition to the circumferential and backfill properties. In addition, the designer must realize that when stresses exist in both directions, the Poisson’s ratio effect must be considered. This finding is supported by the longitudinal failure strains measured during the flexural tests and the field tests. In both types of tests, the pipes failed at approximately the same longitudinal strain level, approximately 1,300 microstrain. On the other hand, in the field tests, the pipes never reached the magnitude of strain associated with failure in the laboratory parallel plate tests.

scholarly journals Applicability of the Cox-Merz Rule to High-Density Polyethylene Materials with Various Molecular Masses

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1218
Author(s):  
Raffael Rathner ◽  
Wolfgang Roland ◽  
Hanny Albrecht ◽  
Franz Ruemer ◽  
Jürgen Miethlinger
Keyword(s):  
Molecular Weight ◽  
Pressure Drop ◽  
High Molecular Weight ◽  
High Density Polyethylene ◽  
Parallel Plate ◽  
Empirical Relationship ◽  
Polymer Processing ◽  
High Density ◽  
Viscosity Data ◽  
Molecular Masses

The Cox-Merz rule is an empirical relationship that is commonly used in science and industry to determine shear viscosity on the basis of an oscillatory rheometry test. However, it does not apply to all polymer melts. Rheological data are of major importance in the design and dimensioning of polymer-processing equipment. In this work, we investigated whether the Cox-Merz rule is suitable for determining the shear-rate-dependent viscosity of several commercially available high-density polyethylene (HDPE) pipe grades with various molecular masses. We compared the results of parallel-plate oscillatory shear rheometry using the Cox-Merz empirical relation with those of high-pressure capillary and extrusion rheometry. To assess the validity of these techniques, we used the shear viscosities obtained by these methods to numerically simulate the pressure drop of a pipe head and compared the results to experimental measurements. We found that, for the HDPE grades tested, the viscosity data based on capillary pressure flow of the high molecular weight HDPE describes the pressure drop inside the pipe head significantly better than do data based on parallel-plate rheometry applying the Cox-Merz rule. For the lower molecular weight HDPE, both measurement techniques are in good accordance. Hence, we conclude that, while the Cox-Merz relationship is applicable to lower-molecular HDPE grades, it does not apply to certain HDPE grades with high molecular weight.

Modern Bimodal High Density Polyethylene for the Nuclear Power Plant Piping System

2009 ◽  
Author(s):  
Adel N. Haddad
Keyword(s):  
High Density Polyethylene ◽  
Nuclear Power ◽  
Large Diameter ◽  
Water System ◽  
High Density ◽  
Nuclear Industry ◽  
Piping System ◽  
Service Water ◽  
Hdpe Pipe ◽  
Related Service

Originally introduced in the 1990s, bimodal HDPE, pipe resins are still finding new niches today, including even nuclear power plants. HDPE pipe grades are used to make strong, corrosion resistant and durable pipes. High density polyethylene, PE 4710, is the material of choice of the nuclear industry for the Safety Related Service Water System. This grade of polymer is characterized by a Hydrostatic Design Basis (HDB) of 1600 psi at 73 °F and 1000 psi at 140 °F. Additionally bimodal high density PE 4710 grades display >2000 hours slow crack growth resistance, or PENT. HD PE 4710 grades are easy to extrude into large diameter pipes; fabricate into fitting and mitered elbows and install in industrial settings. The scope of this paper is to describe the bimodal technology which produces HDPE pipe grade polymer; the USA practices of post reactor melt blending of natural resin compound with black masterbatch; and the attributes of such compound and its conformance to the nuclear industry’s Safety Related Service Water System.

Experimental Analysis of Ring Stiffnesses of Pipes, Made of High Density Polyethylene, due to DIN 16961-2:2010-03 Standard

2012 ◽  
Author(s):  
I. Mehmet Palabiyik ◽  
A. Orhan Yavuz ◽  
Zafer Gemici ◽  
Isminur Gökgöz
Keyword(s):  
Quality Control ◽  
Experimental Analysis ◽  
Manufacturing Process ◽  
High Density Polyethylene ◽  
Parallel Plate ◽  
Constant Load ◽  
High Density ◽  
Load Test ◽  
Plate Load Test ◽  
Hdpe Pipe

The parallel plate load test is used to measure “pipe stiffness” for HDPE pipe. Pipe stiffness is employed as a measure of pipe resistance to bending deformation as well as a quality control index for the manufacturing process. This work presents the results of a series of parallel plate tests conducted on profiled HDPE plastic pipes to determine ring stiffness values. During the study, all pipe samples were tested according to the DIN 16961 2:2010-03 standard. The nominal inside diameters of the test pipes were selected 500 and 600mm. These pipes compressed radially a constant load during 24 hours and deflection were measured by a comparator. Then experimental ring stiffness values were calculated by using these data.

scholarly journals LARGE DIAMETER POLYETHYLENE SUBMARINE OUTFALLS

1984 ◽  
Vol 1 (19) ◽  
pp. 210
Author(s):  
L.A. Jackson
Keyword(s):  
High Density Polyethylene ◽  
State Of The Art ◽  
Large Diameter ◽  
City Council ◽  
High Density ◽  
Gold Coast ◽  
Steel Pipes ◽  
Concrete Pipes ◽  
Polyethylene Pipes ◽  
Navigation Channel

This paper presents the state of the art that has now evolved in Australia and shows the trend towards using high density polyethylene pipes for submarine conditions and the varying techniques and materials utilised. Prior to 1981 High Density Polyethylene (H.D.P.E.) was not produced in Australia in diameters larger than 630mm and even in the available sizes submarine outfalls were in the main constructed of mild steel or concrete pipes. In 1980 the Gold Coast City Council called tenders for the supply and installation of a 1500 metre, 1 metre diameter, outfall across the Southport Broadwater which is an active tidal estuary area. The proposed route crossed a main navigation channel and required trenching up to 8 metres into sand and sandstone. After consideration of the special requirements and high tender prices for conventional materials, Council constructed a temporary 400mm diameter H.D.P.E. outfall while the design of the permanent outfall was re-evaluated. The outfall was eventually constructed by day labour utilising a 1 metre diameter H.D.P.E. at a cost saving of approximately $1.5 million over the lowest tender price utilising steel pipes. Manufacturing facilities were imported into Australia for this job and now other large diameter submarine H.D.P.E. outfalls have been constructed in Australia and this material is now gaining acceptance.

Linear viscoelastic modelling of profiled high density polyethylene pipe

1996 ◽  
Vol 23 (2) ◽  
pp. 395-407 ◽  
Author(s):  
Ian D. Moore ◽  
Fuping Hu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
High Density Polyethylene ◽  
Parallel Plate ◽  
High Density ◽  
Time Dependent ◽  
Element Analysis ◽  
Vertical Diameter ◽  
Polyethylene Pipes ◽  
Linear Viscoelastic

Rheological model parameters for a linear viscoelastic finite element analysis are developed for corrugated polyethylene pipes. Relaxation test data from parallel plate load tests on lined corrugated high density polyethylene pipes are used, for pipes deflected to 5% and 10% vertical diameter decrease. Three-dimensional time-dependent finite element analysis is then used to estimate the time-dependent response of a 610 mm diameter pipe subjected to a constant rate of vertical diameter decrease with time. Predictions are obtained for deflection rates varying over three orders of magnitude, for direct comparison with laboratory test results. Small deflection (5%) relaxation rheology leads to good predictions of measured response up to 3% vertical pipe deflection. Large deflection (10%) rheology yields reasonable predictions for pipe response between 3% and 10% vertical deflection. Levels of strain are examined in the pipe profile, and a peak local tensile strain of 0.6% is estimated for the pipe deflected to 3% vertical diameter decrease. The rheological models should permit prediction of response under parallel plate loading for other pipe profiles. These models might also be used for estimation of pipe response under other loading conditions (such as deep burial in the field).

scholarly journals Modeling benzene permeation through drinking water high density polyethylene (HDPE) pipes

2015 ◽  
Vol 13 (3) ◽  
pp. 758-772 ◽  
Author(s):  
Feng Mao ◽  
Say Kee Ong ◽  
James A. Gaunt
Keyword(s):  
Drinking Water ◽  
High Density Polyethylene ◽  
Distribution Systems ◽  
Water Distribution ◽  
Large Diameter ◽  
Small Diameter ◽  
High Density ◽  
Ethyl Benzene ◽  
Constant Input ◽  
Hdpe Pipes

Organic compounds such as benzene, toluene, ethyl benzene and o-, m-, and p-xylene from contaminated soil and groundwater may permeate through thermoplastic pipes which are used for the conveyance of drinking water in water distribution systems. In this study, permeation parameters of benzene in 25 mm (1 inch) standard inside dimension ratio (SIDR) 9 high density polyethylene (HDPE) pipes were estimated by fitting the measured data to a permeation model based on a combination of equilibrium partitioning and Fick's diffusion. For bulk concentrations between 6.0 and 67.5 mg/L in soil pore water, the concentration-dependent diffusion coefficients of benzene were found to range from 2.0 × 10−9 to 2.8 × 10−9cm2/s while the solubility coefficient was determined to be 23.7. The simulated permeation curves of benzene for SIDR 9 and SIDR 7 series of HDPE pipes indicated that small diameter pipes were more vulnerable to permeation of benzene than large diameter pipes, and the breakthrough of benzene into the HDPE pipe was retarded and the corresponding permeation flux decreased with an increase of the pipe thickness. HDPE pipes exposed to an instantaneous plume exhibited distinguishable permeation characteristics from those exposed to a continuous source with a constant input. The properties of aquifer such as dispersion coefficients (DL) also influenced the permeation behavior of benzene through HDPE pipes.

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