Criteria for gas network renewal: Experimental assessment of traffic loads and cast iron joint escapes

Gas escapes from buried pipes depend on many controllable and uncontrollable factors. External mechanical loads, mainly due to traffic loads, are statistically significant especially for cast iron pipes. The assessment of the relationship between displacement of cast iron joints and the traffic load is studied in order to give some criteria for the design of renovation policy. In particular an experimental analysis of the principal traffic parameters, such as weight, speed and wheel-pipe distance, affecting the relative movement of the bell and spigot is carried out. The acquisition of the micrometric movement has been achieved by using a previously developed measurement system based on LVDT sensors. The statistical analysis of the data obtained indicates a strong correlation between weight and joint displacement. Speed of the autovehicles has been found to be not statistically significant.