Dynamic Test Method for the Evaluation of Butt Welds

 

Additional Information - Posters # 1998 Gothenburg

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 service failures result from the combined effect of the service load and extraneous third party loading. Attempts to measure the behaviour of welds by using il~temal pressurisation are frustrated by this inherent load ratio, but still further by the fact that the weld bead provides additional circumferential reinforcement. If an attempt is made to accelerate the failure process by applying high internal pressurisation the saniple fails in the body of the pipe and not at the weld. This paper describes how dynamic loading has heen applied to both a pressurised and non-pressurised system to cause failure to occur at the weld beadlpipe wall interface in a way and with a fracture morphology analogous to that seen in service.

Please note that the whole article content is available on PPCA website only


Related papers

2018 Las-Vegas : Increasing HDPE butt fusion productivity by optimizing the cool time based on thermal mass characteristics without compromising joint strength

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...

2018 Las-Vegas : Polyolefin pipes in the middle east- today and tomorrow

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...

2016 Berlin : Pipe bursting asbestos cement pipe in compliance with environmental protection agency’s regulations and scientific data collection on the project

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...

2014 Chicago : Butt Fusion in Logistically Challenging Jobsites

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...

2014 Chicago : Introducing PO Pipes into the Middle East – Rising to the Technical Challenges

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...

2012 Barcelona : Stress analysis of elbows and tees of plastic pipes using finite element analysis

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...

2004 Milan : Resistance of PVC-U and PVC-M to Cyclic Fatigue

Author(s) : Whittle, Teo

PVC-U and PVC-M pipes may be used in applications where they are subjected to cyclic pressures generated by the operation of pumps and valves. It is therefore important that the pipe material’s response to cyclic loading is quantified and that pipelines are designed and operated within the material’s established...

2001 Munich : Measurement of Scores and Scratches on PE Pipes used in No-Dig Operations

Author(s) : Stokes, Potter, Muhl, Acland

Research indicates that the scoring of polyethylene pipes that can occur during directional drilling operations in clay soils will not exceed the specification of 10% pipe wall scoring depth. However, a higher level of damage may occur in different types of soils from these operations. Further investigations from...

2001 Munich : Optimising the Performance of Ferrule Straps with PVC Pipes

Author(s) : Stokes, Potter, Metcalfe, Bowman, Graham

The response of three different forms of polyvinyl chloride (PVC) pipe has been explored when the pipes had attached to them ferrule straps. Pipes were subjected to fluctuating internal pressure (fatigue) loading at 20°C, and the lifetimes, location of any failures and the types of failures recorded. Tests were made...

1998 Gothenburg : A New Approach to the Instrumented Falling Weight Method

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...

1998 Gothenburg : A Review of the Latest Stage of a Method That Allows the Testing of Large

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...

1998 Gothenburg : Dynamic Pressure Testing

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...

1998 Gothenburg : Product Development Using the Dynamic (Cycle Pressure) Test

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...

1995 Edinburgh : A Fracture Consideration of the Sinusoidial Behaviour of Fast Fracture in Plastics Pipes

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...

1995 Edinburgh : Behaviour of notched fatigue data

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...

1995 Edinburgh : Factors affecting the implementation of Vee notched plastic pipe tests

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...

1992 Eindhoven : Fundamental Justification of a Fatigue Based Quality Control Test on All Sizes of Plastic Pipe

Author(s) : Lawrence

The limited demand for very large bore plastic pipes systems has resulted in a dearth of associated test data or strategy, but the need to now transport large quantities of water demand closer attention to this problem. The 'type testing' and routine (Q.C. ) testing of plastic pipe systems is already a difficult area,...

1988 Bath : The Possibility of Assessing the Long Term Performance of PE Pipes Using a Quality Control Fatigue Test

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...

1985 York : The Investigation into the Use of Fatigue in Accelerated Quality Control Procedure for 50 Years Life Prediction

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...

The Developing Market for Plastics Pipes in the Middle East and the Need for the GPPA

Author(s) : Lawrence

Members of the Association

BOREALISBOROUGEFormosa Plastics CorporationINEOS O&PIRPCKazanorgsintez PJSCKorea Petrochemical IND. Co., LTD (KPIC)LyondellBasellPetroChina Dushanzi Petrochemical CompanyPRIME POLYMERSABICSCG Chemicals & Thai PolyethyleneSinopecTASNEE
TOP