說是外徑小的鋼管，就可以稱為小口徑鋼管，小口徑厚壁鋼管還可以分為：無縫小口徑鋼管和直縫（也可以稱為焊接）小口徑鋼管，一般在鋼管的外徑89以下的，都可以統稱為小口徑鋼管按生產方法不同可分為熱軋管 、冷軋管 、冷拔管 、擠壓管等， 熱軋無縫管一般在自動軋管機組上生產。實心管坯經檢查并清除表面缺陷截成所需長度， 在管坯穿孔端端面上定心 然后送往加熱爐加熱 在穿孔機上穿孔 在穿孔同時不斷旋轉和前進， 在軋輥和頂頭的作用下， 管坯內部逐漸形成空腔稱毛管， 再送至自動軋管機上繼續軋制后經均整機均整壁厚， 經定徑機定徑， 達到規格要求， 利用連續式軋管機組生產熱軋小口徑鋼管是較先進的方法， 若欲獲得尺寸更小和質量更好的小口徑鋼管， 必須采用冷軋 冷拔或者兩者聯合的方法冷軋通常在二輥式軋機上進行，小口徑鋼管在變斷面圓孔槽和不動的錐形頂頭所組成的環形孔型中軋制， 冷拔通常在單鏈式或雙鏈式冷拔機上進行 擠壓法即將加熱好的管坯放在密閉的擠壓圓筒內穿孔棒與擠壓桿一起運動， 使擠壓件從較小的模孔中擠出， 此法可生產直徑較小的鋼管。

英文版：Small diameter steel pipe, can be called small diameter steel pipe, small diameter thick-walled steel pipe can also be divided into: seamless small diameter steel pipe and longitudinal seam (also known as welding) small diameter steel pipe, generally in the steel pipe under the outer diameter of 89, can be collectively called small diameter steel pipe according to different production methods can be divided into hot-rolled pipe, cold-rolled pipe The hot rolled seamless pipe is usually produced on the automatic tube rolling mill. The solid billet is inspected and the surface defects are cleared and cut to the required length. The billet is centered on the end face of the piercing end of the billet and then sent to the heating furnace for heating. The piercing machine rotates and advances continuously during the piercing. Under the action of the roll and the head, the billet gradually forms a cavity called capillary, which is then sent to the automatic pipe mill to continue. It is an advanced method to produce hot-rolled small-diameter steel pipes by continuous rolling mill. If small-diameter steel pipes with smaller size and better quality are to be obtained, cold-rolled cold-drawn or combined cold-rolled two-roll mill is necessary. The small diameter steel pipe is rolled in a circular pass consisting of a variable section circular groove and a stationary tapered plug. Cold drawing is usually carried out on a single or double chain cold drawing machine by extrusion. The heated billet is placed in an airtight extrusion cylinder and the punch rod moves with the extrusion rod, so that the extruded part is smaller. This method can produce smaller diameter steel pipes.