# 1982 York
Fracture propagation is a phenomenon in which a long brittle crack runs along the pipeline at high speeds of approximately 350 m/s. More stringent operating and test pressures of larger diameter polyethylene gas pipes have had to be introduced nationally. Full scale tests on 250 mm SDR 17.6 medium and high density polyethylene pipes have been conducted to define safe pressure levels for crack arrest. The arrest pressures were found to be highly temperature sensitive.
Author(s) : Ian Aldridge, Declan Robinson, Dave Smart, Chris Reed, Martyn, Greig, Trevor Stafford, David Christie-Lowe, Alec Erskine
For the UK polyethylene (PE) gas pipe network, the first installations now exceed 40 years in the ground, with an original design life of 50 years. It was thus timely to review the current condition and performance history of these first generation PE materials. A major 4 year project was started in 2010 to examine...
Author(s) : Ewing, Greig, Stafford
Funded by a UK government “Smart” Award, the authors have researched, and partially developed, a novel concept for temporarily reducing the external diameter of a PE pipe and then allowing recovery to full diameter as a close fit within a host main. The novelty lies in the four-lobed collapsed pipe geometry, which...
Author(s) : Hoving, Palmlof, Harget, Upperton, Ewing
The performance properties of Cross Linked Polyethylene (PE-X) are reviewed with particular emphasis on extreme temperature operation. Resistance to rapid crack propagation at low temperatures and retention of properties at elevated temperatures are highlighted. The potential availability of a high strength (MRS 12.5)...
Author(s) : Greig
One of the main design criteria for limiting the operational pressures of polyethylene (PE) gas pipes is its resistance to rapid crack propagation (RCP). Below a critical pressure the crack arrests but above the whole pipeline may be fractured. The paper discusses the critical pressures measured during European and...
Author(s) : Ewing, Greig
Operation of high density polyethylene (HDPE) pipes at 7 bar has been very successful in British Gas over the last few years. Using HDPE pipes at higher pressures requires a high level and correct balance of pipe properties of strength, stress crack and rapid crack propagation resistance. Raised levels of jointing...
Author(s) : Ward, Atkinson, Greig, Hansard
A novel die-drawing process has been developed at Leeds University. By incorporating a mandrel, pipes may be expanded hoopwise whilst being drawn axially. Such biaxially-oriented pipes have properties better suited to the transmission of gases and liquids than either isotropic or longitudinally-drawn pipes. In this...
Author(s) : Greig
The catastrophic phenomenon of rapid crack propagation in 250 mm diameter polyethylene pipes has been investigated at a full scale test facility. Tests at +3°C were conducted with pipes, either completely fully of water or containing a small percentage of air. The safe, maximum pressures were measured. Rapid crack...
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) : Greig
As polyethylene pipes increase in size above 250 mm, the avoidance of high-speed brittle fracture propagation becomes of overriding importance. More stringent operating and test pressures have had to be introduced. A full scale test programme on a variety of pipe sizes is being conducted by British Gas. In this paper,...
