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蘋果: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)哈德(de)(de)也(ye)曾(ceng)發(fa)(fa)現圓(yuan)鋼(gang)斜(xie)(xie)軋時(shi)工(gong)(gong)(gong)件中心(xin)(xin)發(fa)(fa)生撕裂，產生孔(kong)腔的現象，但是(shi)他對這一現象不(bu)夠(gou)敏感，后(hou)來(lai)只好另辟蹊徑，發(fa)(fa)展另一種生產空心(xin)(xin)坯(pi)(pi)(pi)的工(gong)(gong)(gong)藝(yi)，在(zai)(zai)1891年(nian)(nian)發(fa)(fa)明(ming)了(le)水(shui)壓(ya)沖(chong)孔(kong)工(gong)(gong)(gong)藝(yi)，比曼內(nei)斯(si)曼兄(xiong)弟發(fa)(fa)明(ming)斜(xie)(xie)軋穿(chuan)(chuan)孔(kong)晚了(le)6年(nian)(nian)，通(tong)常所講的“艾(ai)(ai)哈德(de)(de)工(gong)(gong)(gong)藝(yi)”（Ehrhardt Process)乃(nai)由水(shui)壓(ya)沖(chong)孔(kong)和頂(ding)(ding)管延伸兩個(ge)工(gong)(gong)(gong)藝(yi)過程組(zu)成。1893年(nian)(nian)初艾(ai)(ai)哈德(de)(de)在(zai)(zai)德(de)(de)文《鋼(gang)與鐵》雜志上發(fa)(fa)表文章稱：水(shui)壓(ya)沖(chong)孔(kong)工(gong)(gong)(gong)藝(yi)是(shi)生產空心(xin)(xin)坯(pi)(pi)(pi)的新工(gong)(gong)(gong)藝(yi)，它(ta)與斜(xie)(xie)軋穿(chuan)(chuan)孔(kong)工(gong)(gong)(gong)藝(yi)截然不(bu)同，它(ta)對不(bu)銹(xiu)鋼(gang)管坯(pi)(pi)(pi)質量的要(yao)求(qiu)沒有斜(xie)(xie)軋穿(chuan)(chuan)孔(kong)工(gong)(gong)(gong)藝(yi)那么高。采(cai)用(yong)頂(ding)(ding)管環(huan)頂(ding)(ding)制無縫(feng)不(bu)銹(xiu)鋼(gang)管的工(gong)(gong)(gong)藝(yi)則要(yao)發(fa)(fa)明(ming)得晚一些，艾(ai)(ai)哈德(de)(de)是(shi)在(zai)(zai)1899年(nian)(nian)在(zai)(zai)杜(du)市的Reisholz地(di)方建(jian)立(li)Rheinmetall工(gong)(gong)(gong)廠時(shi)采(cai)用(yong)頂(ding)(ding)管環(huan)以(yi)延伸沖(chong)孔(kong)坯(pi)(pi)(pi)，由此正(zheng)式誕(dan)生了(le)艾(ai)(ai)哈德(de)(de)工(gong)(gong)(gong)藝(yi)，亦即頂(ding)(ding)管工(gong)(gong)(gong)藝(yi)。他在(zai)(zai)1902年(nian)(nian)的德(de)(de)國鋼(gang)鐵工(gong)(gong)(gong)程師年(nian)(nian)會上發(fa)(fa)表論文，闡述艾(ai)(ai)哈德(de)(de)工(gong)(gong)(gong)藝(yi)的技術內(nei)涵(han)，并在(zai)(zai)英(ying)美兩國申請了(le)專(zhuan)利。

  艾哈(ha)德(de)在(zai)杜市Reisholz 區(qu)建(jian)立不(bu)銹(xiu)鋼(gang)(gang)管(guan)(guan)廠(chang)與(yu)德(de)國海(hai)軍部的(de)(de)(de)訂(ding)貨(huo)有關，德(de)國海(hai)軍部于1898年2月提出一份無縫(feng)不(bu)銹(xiu)鋼(gang)(gang)管(guan)(guan)訂(ding)貨(huo)單(dan)，由于數量(liang)大，而且要求交貨(huo)時間緊，因此(ci)海(hai)軍部明確(que)表(biao)示位(wei)于杜市的(de)(de)(de)曼內(nei)斯曼鋼(gang)(gang)管(guan)(guan)公司和 Rheinmetall工(gong)廠(chang)都參(can)與(yu)生(sheng)產，艾哈(ha)德(de)原來采(cai)用穿孔和熱(re)拔相結合(he)的(de)(de)(de)辦法生(sheng)產鋼(gang)(gang)管(guan)(guan)，他接受這份訂(ding)單(dan)后(hou)，就在(zai)Reisholz建(jian)立不(bu)銹(xiu)鋼(gang)(gang)管(guan)(guan)廠(chang)，在(zai)水壓沖(chong)孔工(gong)藝(yi)的(de)(de)(de)基礎上添加空心(xin)坯延伸工(gong)藝(yi)即采(cai)用頂(ding)管(guan)(guan)坯的(de)(de)(de)頂(ding)管(guan)(guan)工(gong)藝(yi)，于是誕生(sheng)了完整的(de)(de)(de)艾哈(ha)德(de)工(gong)藝(yi)。