Mannesmann Aktiengesellschaft

Norbert Niehaus

Wilhelm Schwenk

Werner Friehe

Rolf K Popperling

Horst Bester

A method of applying a metallic coating to metallic sealing and/or threaded regions of steel pipes which are under high pressure per unit of surface by a pretreatment of the surface to be coated which consists of a cleaning and degreasing and an electrolytic deposition of a layer of tin by a first heat treatment at a temperature between about 150.degree. and about 200.degree. C. and a second brief heat treatment above the melting point of tin with subsequent cooling is provided. A metallic coating which is formed using said method is also provided.

Method for forming a metallic coating on steel pipes

The thread of tubing to be used in the oil and gas industry and possibly additional services such as fee ing surfaces are cleaned, degreased, and pickled, nickel-coated without electric current at a layer thickness of about 1 micrometer, followed by electrolytic plating, preferably tin-plating, followed by storage at a temperature within the range from 150.degree. to about 200.degree., which is followed by brief heating for melting the tin coating, whereupon the article is quenched.

Method for electrolytically tin plating articles

Steel is to be austenitic-ferritic at a 1:1 ratio of austenite to ferrite and contains particular alloy elements. The principal feature is, limiting the sulphure content to below 0.005% in order to obtain a particularly high toughness transversely to the main direction of working.

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Dusseldorf, Germany

Norbert Niehaus