US Pat. No. 10,214,862

CASING TUBE AND MANUFACTURING METHOD THEREOF

NINGBO SHUXIANG NEW MATER...

1. A casing tube for being pre-buried in a railway transport system, comprising:at least two tube bodies, each having an inner-side surface, an outer-side surface, and at least a retaining element provided at said inner-side surface, wherein when said two tube bodies are coupled with each other to form a tubular configuration, a screw channel is formed within said inner-side surfaces of said tube bodies for receiving a screw, wherein said retaining elements formed a thread portion integrally formed at said inner-side surfaces for engaging with the screw, wherein each of said tube bodies further has a plurality of locating elements spacedly and radially protruded from said outer-side surface, and at least one locating slot formed between two of said locating elements.