公开(公告)号：US3817289A

公开(公告)日：1974-06-18

申请号：US32477373

申请日：1973-01-18

申请人： COFFMAN H

发明人： COFFMAN H

IPC分类号： F16L9/08 ,  F16L25/00

CPC分类号： F16L9/08

摘要： A precast unit, preferably of cementitious material, of circular outline having stone-like block units on the outer surface separated by mortar joints and top shoulder annular portions to serve as a guide to enable stacking like units above each other. The inner surface of each unit and outer surface of each projection extend in a downwardly and outwardly extending direction to provide a stepped inner wall.

摘要翻译： 具有圆形轮廓的预制单元，具有在外表面上具有石状块单元的圆形轮廓，由砂浆接头和顶肩环形部分分开，以用作引导以使得能够堆叠在彼此之上。 每个单元的内表面和每个突起的外表面沿向下和向外延伸的方向延伸以提供阶梯状的内壁。