Pfeiffer 博士曾經在一篇文章中稱：“若要探討1886年后無縫香蕉視頻app連接:不銹鋼管生產技術的發展，就會發現這一技術沿著兩個方向在發展：一方面是斜軋穿孔和延伸技術的多樣化的發展；另一方面是Heinrich Ehrhardt 研究的水壓沖孔工藝的發展，Ehrhardt于1899年在他的 Dusseldorf的 Reisholz 建立了頂管工廠。”當時，Ehrhardt從曼氏兄弟初期所遇到的困難中吸取教訓，他研制出的水壓沖孔工藝，對管坯質量的要求沒有斜軋穿孔工藝那么高，環式孔型頂管工藝基本上是拔制工藝，因此Ehrhardt軋管工藝是完全不同于曼內斯曼穿孔工藝的另一條途徑。

  在(zai)(zai)19世紀(ji)80年(nian)(nian)代艾(ai)(ai)哈(ha)(ha)(ha)德也曾發現(xian)(xian)圓鋼(gang)(gang)(gang)斜軋時工(gong)(gong)(gong)件(jian)中(zhong)心發生(sheng)撕裂，產生(sheng)孔(kong)(kong)腔的(de)(de)(de)現(xian)(xian)象(xiang)，但是(shi)(shi)他(ta)對(dui)這一(yi)現(xian)(xian)象(xiang)不(bu)(bu)夠敏感，后(hou)來只好另辟蹊(xi)徑，發展另一(yi)種生(sheng)產空心坯的(de)(de)(de)工(gong)(gong)(gong)藝(yi)，在(zai)(zai)1891年(nian)(nian)發明(ming)了水(shui)壓沖孔(kong)(kong)工(gong)(gong)(gong)藝(yi)，比曼(man)內斯(si)曼(man)兄弟發明(ming)斜軋穿孔(kong)(kong)晚(wan)了6年(nian)(nian)，通常(chang)所講(jiang)的(de)(de)(de)“艾(ai)(ai)哈(ha)(ha)(ha)德工(gong)(gong)(gong)藝(yi)”（Ehrhardt Process)乃由(you)水(shui)壓沖孔(kong)(kong)和頂(ding)管延伸(shen)兩個工(gong)(gong)(gong)藝(yi)過程組成。1893年(nian)(nian)初艾(ai)(ai)哈(ha)(ha)(ha)德在(zai)(zai)德文《鋼(gang)(gang)(gang)與(yu)鐵》雜(za)志上(shang)發表文章稱：水(shui)壓沖孔(kong)(kong)工(gong)(gong)(gong)藝(yi)是(shi)(shi)生(sheng)產空心坯的(de)(de)(de)新工(gong)(gong)(gong)藝(yi)，它與(yu)斜軋穿孔(kong)(kong)工(gong)(gong)(gong)藝(yi)截然不(bu)(bu)同(tong)，它對(dui)不(bu)(bu)銹鋼(gang)(gang)(gang)管坯質(zhi)量的(de)(de)(de)要求(qiu)沒有斜軋穿孔(kong)(kong)工(gong)(gong)(gong)藝(yi)那么(me)高。采(cai)用頂(ding)管環頂(ding)制無縫不(bu)(bu)銹鋼(gang)(gang)(gang)管的(de)(de)(de)工(gong)(gong)(gong)藝(yi)則(ze)要發明(ming)得晚(wan)一(yi)些，艾(ai)(ai)哈(ha)(ha)(ha)德是(shi)(shi)在(zai)(zai)1899年(nian)(nian)在(zai)(zai)杜市(shi)的(de)(de)(de)Reisholz地方建立(li)Rheinmetall工(gong)(gong)(gong)廠時采(cai)用頂(ding)管環以(yi)延伸(shen)沖孔(kong)(kong)坯，由(you)此(ci)正式(shi)誕生(sheng)了艾(ai)(ai)哈(ha)(ha)(ha)德工(gong)(gong)(gong)藝(yi)，亦(yi)即頂(ding)管工(gong)(gong)(gong)藝(yi)。他(ta)在(zai)(zai)1902年(nian)(nian)的(de)(de)(de)德國(guo)鋼(gang)(gang)(gang)鐵工(gong)(gong)(gong)程師(shi)年(nian)(nian)會(hui)上(shang)發表論(lun)文，闡述艾(ai)(ai)哈(ha)(ha)(ha)德工(gong)(gong)(gong)藝(yi)的(de)(de)(de)技術內涵(han)，并在(zai)(zai)英美兩國(guo)申(shen)請了專(zhuan)利(li)。

  艾(ai)(ai)哈德在(zai)(zai)杜市Reisholz 區(qu)建(jian)(jian)立(li)不銹鋼(gang)(gang)管(guan)(guan)廠與(yu)(yu)德國海(hai)軍部的訂(ding)貨有關，德國海(hai)軍部于(yu)(yu)1898年2月提出一份(fen)無縫不銹鋼(gang)(gang)管(guan)(guan)訂(ding)貨單，由于(yu)(yu)數(shu)量大，而且要求交貨時間緊(jin)，因此(ci)海(hai)軍部明確表示位(wei)于(yu)(yu)杜市的曼內斯曼鋼(gang)(gang)管(guan)(guan)公司(si)和 Rheinmetall工(gong)廠都參(can)與(yu)(yu)生產，艾(ai)(ai)哈德原來(lai)采(cai)用(yong)穿孔和熱拔(ba)相結合的辦(ban)法生產鋼(gang)(gang)管(guan)(guan)，他接(jie)受這份(fen)訂(ding)單后，就在(zai)(zai)Reisholz建(jian)(jian)立(li)不銹鋼(gang)(gang)管(guan)(guan)廠，在(zai)(zai)水壓沖(chong)孔工(gong)藝(yi)(yi)的基(ji)礎(chu)上添加空心(xin)坯延伸工(gong)藝(yi)(yi)即采(cai)用(yong)頂(ding)(ding)管(guan)(guan)坯的頂(ding)(ding)管(guan)(guan)工(gong)藝(yi)(yi)，于(yu)(yu)是(shi)誕生了完整的艾(ai)(ai)哈德工(gong)藝(yi)(yi)。