EXPERIMENTAL STUDY OF PIPELINE SCOURING ON SEABED AND IN-TRENCH CONDITIONS UNDER REGULAR WAVE MOTION

Submarine pipeline is one of the media for the distribution of oil and gas from offshore platform to onshore which is considered more efficient. However, the use of pipeline still has any problem about its positioning that can be affected by the environment condition. The pattern of water flow will change when there is a structure that blocks flow. That can cause scouring at the bottom of the pipeline resulting in a freespan pipeline condition. If the pipeline design was not correctly calculated, it then will be experienced the structural failure for a short time. In the paper, the characteristic of pipeline scouring on sandbed and in-trench condition is investigated into the time scale of local scour in changing the regular wave condition in the the flume tank. The test model used are a PVC pipe with 1.5 inch in diameter and the median grain size diameter is d50 by 0.55 mm. The placement of the pipe on the basis varied in conditions laid on the bed (e/D = 0) and in-trench condition in changing the ratio of embedment to diameter (e/D = -0.05, e/D = -0.075 and e/D = -0.10). Moreover, the water depth was also varied to 40 cm and 50 cm. The largest depth and width of scouring occurs in pipe conditions (e / D = 0) with a water depth of 40 cm and a wave height of 15 cm, namely, scouring depth (S) = 0.989 cm and scouring width (w) = 8.314 cm. The scour depth maximum was reached within 25 minutes.