Fundamental Justification of a Fatigue Based Quality Control Test on All Sizes of Plastic Pipe

Author(s) : Amanda Hawkins, Jason Lawrence, Xiangli Meng

High Density Polyethylene pipes are used in various applications due to the material’s superior chemical resistance, pressure capability, and ductility. For the material to perform at the optimal design criteria, the connections and fabrications must be fused using repeatable procedures that specify proper fusion...

Author(s) : Robert Lawrence, Mohana Murali

The paper covers the growth of the polyethylene pipe sector in the Middle East from the 90s to the present. The initial slow uptake was related to ignorance of the material properties from the end users through to designers and installers. Recently the Middle East has become a world leader in the use of ever larger...

Author(s) : Edward Alan Ambler, John Matthews, Lawrence Pultz, Ryan Stowe

This paper summarizes the design and implementation of the largest asbestos cement pipe bursting project performed to date within the United States. The paper also presents regulatory information required to properly track and document an asbestos cement pipe bursting project while meeting the National Emissions...

Author(s) : Jason A. Lawrence

Traditional butt fusion technology relies upon high power electrical sources such as power grids or site generators to provide the power for facing operations, heating operations, and the required machine movements. Some jobsites, however, pose special challenges, such as remote location and the lack or unreliability...

Author(s) : Robert J Lawrence

In the Middle East the environment is exceptionally aggressive for all pipe systems due to the high temperatures, the high groundwater table and the very saline soils. This obviously makes metallic pipes and cement based pipes high risk options but it also poses challenges for polyolefin (PO). In this paper the author...

Author(s) : A.C. Seibi, R. J. Lawrence, R. Jepson and Z. Tarik

Design and fabrication of plastic pipe fittings have been governed by ISO 4427 where pressure derating factors of 0.8 and 0.5 have been used respectively for fabricated elbows and tees. However, laboratory data generally indicate that these derating factors are very conservative. Moreover, the design of distribution...

Author(s) : Lawrence, Rasbash, Potter, Teo

Structured wall plastic pipe has been in existence for many years, but there remains a need for an appropriate method for assessing the durability of their comparatively thin walls in actual service. In normal operation this has not manifest itself as a problem, but the fact that damage can be sustained during...

Author(s) : Lawrence, Potter, Teo

The short term testing of any plastic pipe for its prospective longevity in service is extremely difficult because it requires some accelerated technique which needs to work within or verv close to the normal operatin? strains if extensive creep processes are to be avoided. The problem has now been exacerbated by the...

Author(s) : Lawrence, Teo, Potter

There is increasing evidence that dynamic testing is a most powerful. if not the only practical, method of evaluating whole plastic pipe for its long term service potential. Indeed in some instances this method is used as the primary indicator of performance in the researcNdevelopmentaI process of these products :...

Author(s) : Lawrence, Potter, Teo

When butt welds fail in servicc it is normal to find that the initiation site of the fracture occurs at the point where the roll bead attaches to the main body of the pipe. The ratio of hoop stress to longitudinal stress for 'thin walled' pipe is approximately 2 : 1 and so it is more likely that these transverse...

Author(s) : Ansell, Lawrence

Recent years have seen the steadily increasing use of thermoplastics for pipes and fittings for domestic hot and cold water supply and heating installations. Plastic pipe systems, in particular those that incorporate a push-in design offer considerable advantages over conventional pipe systems. However, manufacturers...

Author(s) : Lawrence

Department of Manufacturing Enginineering and Design. University of East London, Dagenham Essex. RM8 2AS. UK. Abstract The phenomenon of rapid crack propagation in a pre-notched plastic pipes that are filled or partially filled with pressurised pas has now k e n incorporated into an indostrial requirement typically I...

Author(s) : Lawrence, Potter, Teo

This paper first outlines the case supporting the use of a fatigue based test method for plastlc pipes. listing the factors that have to be addressed in its use and by reference to a large body of other work justifies its adoption into the pipe industry. It then presents further evidence that support the case that...

Author(s) : Lawrence, Potter, Teo

The ultimate reliability of the data generated on tests, both static and dynamic, on "notched" plastic pipes samples is cmcially dependent upon the perfection of the actual notch root and the material immediately surrounding it. This paper d d e r s a number of the important factors relating to the production of the...

Author(s) : Greig, Lawrence

Hydrostatic s~ress rupture testing at 80°C of polyethylene gas pipe currently takes sver 1000 ho7.1rs to determine its good stress cracking performance. This is excessively long for quailty control purposes so a rapid rest is being developed using fatigue pressurlsac. :on, 2gajn on notched...

Author(s) : Lawrence

Polyethylene gas supply systems are designed for a minimum of 50 years life, but as long term data, both laboratory and field is difficult to obtain, long term assessments are based on an extrapolation of Quality Control and other short term tests. An essential requirement is that Polyethylene should be highly...

Author(s) : Lawrence