FORM 6 - K SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Report of Foreign Private Issuer Pursuant to Rule 13a - 16 or 15d - 16 of the Securities Exchange Act of 1934 As of February 1, 2006 TENARIS, S.A. (Translation of Registrant's name into English) TENARIS, S.A. 46a, Avenue John F. Kennedy L-1855 Luxembourg (Address of principal executive offices) Indicate by check mark whether the registrant files or will file annual reports under cover Form 20-F or 40-F. Form 20-F__X__ Form 40-F____ Indicate by check mark whether the registrant by furnishing the information contained in this Form is also thereby furnishing the information to the Commission pursuant to Rule 12G3-2(b) under the Securities Exchange Act of 1934. Yes____ No__X__ If "Yes" is marked, indicate below the file number assigned to the registrant in connection with Rule 12g3-2(b): 82- . The attached material is being furnished to the Securities and Exchange Commission pursuant to Rule 13a-16 and Form 6-K under the Securities Exchange Act of 1934, as amended. This report contains Tenaris's press release announcing that it has completed the acquisition of Acindar welded pipe plant. SIGNATURE Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized. Date: February 1, 2006 Tenaris Completes Acquisition of Acindar Welded Pipe Plant LUXEMBOURG--(BUSINESS WIRE)--Jan. 31, 2006--Tenaris S.A. (NYSE:TS) (BCBA:TS) (BMV:TS) (BI:TEN) announced today that, through its Argentine welded pipe subsidiary, Siat S.A., it has completed the acquisition of the welded pipe assets and facilities of Acindar Industria Argentina de Aceros S.A. (Acindar) located in Villa Constitucion, Santa Fe, for US$28 million. The facilities acquired have an annual capacity of 80,000 tons of welded pipes whose small diameter range largely complements the range of welded pipes that Tenaris currently produces in Argentina. Tenaris is a leading global manufacturer of seamless steel pipe products and provider of pipe handling, stocking and distribution services to the oil and gas, energy and mechanical industries and a leading regional supplier of welded steel pipes for gas pipelines in South America. Domiciled in Luxembourg, it has pipe manufacturing facilities in Argentina, Brazil, Canada, Italy, Japan, Mexico, Romania and Venezuela and a network of customer service centers present in over 20 countries worldwide. CONTACT: Tenaris Nigel Worsnop, 1-888-300-5432 www.tenaris.com