Pfeiffer 博士曾經在一篇文章中稱：“若要探討1886年后無縫久久99國產精品久久99果凍傳媒: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80年(nian)(nian)代(dai)艾(ai)(ai)哈(ha)(ha)德也曾發(fa)(fa)現(xian)圓鋼(gang)斜軋時工(gong)(gong)(gong)(gong)件中(zhong)心(xin)發(fa)(fa)生(sheng)(sheng)撕裂，產(chan)生(sheng)(sheng)孔(kong)腔的現(xian)象(xiang)，但是(shi)(shi)他對(dui)這(zhe)一現(xian)象(xiang)不夠敏(min)感，后來只好(hao)另辟蹊徑，發(fa)(fa)展另一種生(sheng)(sheng)產(chan)空心(xin)坯的工(gong)(gong)(gong)(gong)藝(yi)(yi)(yi)，在(zai)(zai)1891年(nian)(nian)發(fa)(fa)明了(le)水(shui)壓沖孔(kong)工(gong)(gong)(gong)(gong)藝(yi)(yi)(yi)，比曼(man)內斯曼(man)兄弟發(fa)(fa)明斜軋穿(chuan)孔(kong)晚(wan)了(le)6年(nian)(nian)，通(tong)常(chang)所講的“艾(ai)(ai)哈(ha)(ha)德工(gong)(gong)(gong)(gong)藝(yi)(yi)(yi)”（Ehrhardt Process)乃由(you)水(shui)壓沖孔(kong)和頂管(guan)(guan)延(yan)伸(shen)兩(liang)個(ge)工(gong)(gong)(gong)(gong)藝(yi)(yi)(yi)過程組成。1893年(nian)(nian)初艾(ai)(ai)哈(ha)(ha)德在(zai)(zai)德文(wen)《鋼(gang)與鐵(tie)(tie)》雜志上發(fa)(fa)表文(wen)章稱：水(shui)壓沖孔(kong)工(gong)(gong)(gong)(gong)藝(yi)(yi)(yi)是(shi)(shi)生(sheng)(sheng)產(chan)空心(xin)坯的新工(gong)(gong)(gong)(gong)藝(yi)(yi)(yi)，它與斜軋穿(chuan)孔(kong)工(gong)(gong)(gong)(gong)藝(yi)(yi)(yi)截然不同，它對(dui)不銹鋼(gang)管(guan)(guan)坯質量(liang)的要(yao)求沒有斜軋穿(chuan)孔(kong)工(gong)(gong)(gong)(gong)藝(yi)(yi)(yi)那么高。采(cai)用頂管(guan)(guan)環(huan)頂制(zhi)無縫不銹鋼(gang)管(guan)(guan)的工(gong)(gong)(gong)(gong)藝(yi)(yi)(yi)則(ze)要(yao)發(fa)(fa)明得晚(wan)一些，艾(ai)(ai)哈(ha)(ha)德是(shi)(shi)在(zai)(zai)1899年(nian)(nian)在(zai)(zai)杜市(shi)的Reisholz地方建立(li)Rheinmetall工(gong)(gong)(gong)(gong)廠時采(cai)用頂管(guan)(guan)環(huan)以延(yan)伸(shen)沖孔(kong)坯，由(you)此正式誕(dan)生(sheng)(sheng)了(le)艾(ai)(ai)哈(ha)(ha)德工(gong)(gong)(gong)(gong)藝(yi)(yi)(yi)，亦即頂管(guan)(guan)工(gong)(gong)(gong)(gong)藝(yi)(yi)(yi)。他在(zai)(zai)1902年(nian)(nian)的德國鋼(gang)鐵(tie)(tie)工(gong)(gong)(gong)(gong)程師年(nian)(nian)會上發(fa)(fa)表論(lun)文(wen)，闡(chan)述艾(ai)(ai)哈(ha)(ha)德工(gong)(gong)(gong)(gong)藝(yi)(yi)(yi)的技術內涵(han)，并(bing)在(zai)(zai)英美兩(liang)國申請了(le)專利。

  艾(ai)哈德(de)在(zai)杜市(shi)Reisholz 區建立不(bu)銹(xiu)鋼管廠(chang)與德(de)國(guo)海(hai)軍(jun)部(bu)(bu)的(de)(de)(de)訂貨(huo)(huo)有關，德(de)國(guo)海(hai)軍(jun)部(bu)(bu)于(yu)1898年2月提(ti)出一份(fen)無縫不(bu)銹(xiu)鋼管訂貨(huo)(huo)單，由于(yu)數(shu)量大(da)，而且要求交貨(huo)(huo)時間(jian)緊，因(yin)此(ci)海(hai)軍(jun)部(bu)(bu)明確表示位于(yu)杜市(shi)的(de)(de)(de)曼內斯曼鋼管公(gong)司和 Rheinmetall工(gong)廠(chang)都參與生產，艾(ai)哈德(de)原來(lai)采(cai)用(yong)穿(chuan)孔(kong)和熱拔相結合的(de)(de)(de)辦法(fa)生產鋼管，他接受這(zhe)份(fen)訂單后，就在(zai)Reisholz建立不(bu)銹(xiu)鋼管廠(chang)，在(zai)水壓沖孔(kong)工(gong)藝的(de)(de)(de)基礎(chu)上添(tian)加空心坯延(yan)伸(shen)工(gong)藝即(ji)采(cai)用(yong)頂管坯的(de)(de)(de)頂管工(gong)藝，于(yu)是誕生了完(wan)整的(de)(de)(de)艾(ai)哈德(de)工(gong)藝。