165 Expansion Measure Since PP pipes have a large linear expansion coefficient compared to other materials, an expansion/contraction measure is required in the case of piping temperature fluctuation. Material PP PVC PVDF Linear Expansion Coefficient (×10.4/｢ｪC) 1.1 0.8 1.3 . Handling With Elbow Stress caused by heat expansion/contraction is distributed by arranging piping two- and three-dimensional ways with elbows. *) Actual design needs to be finalized after fully considering the piping stress in terms of fitting interval dimensions and pipe support locations. Elbow (Passing) (Good) (Excellent) Flat U-Shape Elbow (Passing) (Good) (Excellent) Three-dimensional U-Shape Elbow (Passing) (Good) (Excellent) Measure for Branch Part