PROBLEM TO BE SOLVED: To provide a hollow tube for green house which can be inexpensively produced using a prior hollow tube production facility, in which fastening intensity of each kind of a fitting such as a cross is high, and which can be easily bent.SOLUTION: An octagonal hollow tube for green house comprises: a linear hollow straight tube 2 whose cross section is formed into an octagonal shape over whole length direction； a hollow bent tube 1 whose cross section is formed into an octagonal shape, whose one end is a linear eaves part, whose the other end is an almost linear roof part, whose intermediate part is a bent part bent in an arc shape. The hollow bent tube 1 is configured so that, a bent outer surface 12 which is an outermost part of the bent part and a bent inner surface 11 which is an innermost part of the bent part are flat surfaces. Surfaces of at least parts of the hollow bent tube 1 and hollow straight tube 2 are subjected to satin processing, a rough surface is formed thereon, and a friction coefficient is increased.SELECTED DRAWING: Figure 2COPYRIGHT: (C)2020,JPO&INPIT【課題】従来の中空管製造設備を利用して安価に製造可能で、十字等の各種接手の緊締強度が高く、しかも曲げ加工容易な温室用中空管を提供する。【解決手段】長さ方向全体に亘って直線状の断面八角形の中空直管２と、一方端が直線状の軒部で他端が略直線状の屋根部で中間部が円弧状に湾曲した湾曲部である断面八角形の中空湾曲管１と、の組み合わせからなる温室用中空管であって、中空湾曲管１は、湾曲部の最も外側に位置する湾曲外面１２と最も内側に位置する湾曲内面１１が平坦面とされている。また、中空湾曲管１と中空直管２の少なくとも一部の表面は、梨地加工されて粗面が形成され摩擦係数が増大されている。【選択図】図２
