Abstract
In the past, the use of RT and workmanship criteria for pipelaying is the preferred method due to smaller capital expenditure and relatively easier to implement. The dependency on RT personnel and welder's skill and efficiency are the key factors in ensuring weld integrity and improved cost savings. This method have been proven in terms of weld integrity and also cost saving to the company.
Over the years, there are increasing concerns over the weld integrity, weld repair cost due number of weld repairs and decreased in productivity. Typical weld defects are incomplete penetration (IP) due to manual fit up, incomplete fusion (IF) and porosity. These defects are viewed and measured from a 2D perspective based on RT interpretation. The actual defect size (width) and its distance from the pipeline wall is unknown. In comparison, the utilization of AUT is able to size the defects based on its length, width and height. This will essentially detect all the defects in the weldment and eliminate all the missed out defects by RT.
By embarking on the use of AUT and ECA approach, less downtime and reduced weld repair rates is expected. This leads to enhancement of weld integrity and reduction of the overall cost of the projects as well. The use of Gas Metal Arc Welding (GMAW) process with minimum repair rate has increased the productivity and layrate of pipelaying barges. The overall weld repair rate has been to a minimum i.e. 2% lesser than company's target which leads to less downtime. These improvements allow for the reduction on the number of days required to install the pipeline, allowing immense cost savings on the barge daily rental.
In 2014, the AUT and ECA have realised more than RM20million cost savings based on the reduction of weld repairs. The pipeline was later hydrotested and commissioned prior to gas in. No anomalies were observed. The use of AUT and ECA has proven to be cost effective and enhance pipeline integrity in comparison to the conventional RT and workmanship criteria.
