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Polylactidacid (PLA) is a type of bio-based and bio-degradable plastic. This substance is commonly used in the medical field since it is biocompatible and does not hurt bodily tissues. In this study, PLA plastic will be combined with chitosan (CS) via injection molding. The addition of CS to compensate for the absence of PLA with hydrophobic characteristics. CS has hydrophilic characteristics, which allow it to absorb water and bond with biological tissues. The contact angle test revealed that pure PLA is a hydrophobic material, but the PLA: CS alloy is a hydrophilic alloy.

It is known that some welding results were defect in the Saudi Aramco project, particularly at the TKY joint and splice joint, thus there is a reparation needed with the specific type of defect which is lack of fusion. The method used is the Pareto diagram, control diagram and fish bone diagram -to find out the graphs and the causes of the resulting structural welding results. The results shown by the pareto diagram state that for an event, about 80% of the effect is caused by 20% of the cause, the type of damage that often occurs in the welding results caused by a lack of fusion is 50%, consisting 23 joints of the 46 joints produced. Meanwhile, from the control chart, all data of the structural welding have been placed at the control limit. Based on the fish bone diagram, some of the causes the lack of fusion defect are because several factors such as human, machine and method, material and environmental factors.

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