Journal of Pipeline Systems Engineering and Practice

Bell split, in which a shard is separated from the bell end of a bell-spigot joint, is a predominant failure mode (in addition to longitudinal facture) that is observed in lead-caulked bell-spigot joints of large-diameter cast-iron pipes installed between 1850 and the early 1960s. This paper addresses three specific issues related to this type of failure of lead-caulked bell-spigot joints: (1) the extent to which cast-iron pipe joints can rotate without inducing stress in the bell; (2) the behavior of the bell–spigot lead-caulked joints; and (3) an estimate of the degree of settlement that two or more contiguous segments of jointed cast-iron pipe can tolerate before failure. The procedures described in this paper were motivated by the need to understand and explain the circumstances that lead to this failure mode in large-diameter cast-iron pipes. A mechanistic model accounts for lead material nonlinearity, wet and dry joint conditions encountered in water and gas pipelines, respectively, and existence or absence of asphalt coating on the outer pipe surface. The model is validated against experimental tests conducted in the mid-1930s on lead-caulked bell-spigot joints and is subsequently used to develop another model to predict the cumulative joint response of two or more contiguous pipe segments resting on an elastic medium and subject to overburden pressure followed by ground movement. Illustrative analyses of 400 and 1,200 mm diameter pipes clearly show that the extent to which a pipe joint can rotate without failure when subjected to ground movement gets smaller as the pipes become larger. The models developed in this paper to characterize joint behavior can be used to monitor pipe joint condition if actual joint rotations are measured when conducting pipe inspection.

One way to continuously monitor the whole water distribution system is to equip pipes with many small sensors. If these sensors are to be integrated within the pipe walls, it is important to assess their impact on the structural integrity of the pipes, but embedding pipes with these microchips for testing would allow limited control of the position and orientation of the microchips. Therefore, microchips of a few millimeters in size and different shapes were embedded within small-scale polyethylene samples. Pipes are subject to a range of different stresses during their lifetime including hoop, bending, and potentially local impact stresses, and long-term creep effects. This paper focuses on the bending, flexural creep, and impact stresses, with some examples from the tensile tests also presented. The key findings are that there is little effect of the microchips on the 50-year flexural moduli and the short-term flexural properties of the polymer, although there was a significant improvement in the toughness and a reduction in the tensile strength.

The hazardous exposure and self-burial of a submarine pipeline were studied based on the investigation of a submarine pipeline in the sand wave area in the South China Sea, as well as on statistical data and mathematical calculations. The results indicate that the pipeline free span in the area was mainly induced by seabed erosion, sand wave movement, and human disturbance. Extreme weather events cause severe impacts on seabed topography and the pipeline condition. The burial status of the pipe is mainly controlled by the evolution of local seabed topographical conditions, i.e., the amount of sediment load and the movement of seabed sand waves. The migration of the continuous small-scale sand waves facilitates the self-burial of pipes, while the migration of isolated large-scale sand waves creates potential hazards for pipelines because of the existing free span continues to grow on both sides of the sand wave.

One of the important trends of development of hydromechanization in hydraulic engineering is the transport of solids in the form of slurries. Slurry is a thick suspension of solids in a liquid. Clogging of the pipeline carrying slurry will not occur if the velocity of the slurry is more than some critical value. Critical flow velocity, which is the minimum velocity to maintain all solid particles in a suspension condition, is the important design parameter in slurry transport through pipelines. Gene-expression programming (GEP) and adaptive neuro-fuzzy inference system (ANFIS) models are developed in this study for the estimation of critical velocity. The estimated critical velocity by GEP and ANFIS models are compared with existing empirical equations and it is found that the ANFIS model produces better results compared with GEP and other existing equations.