Abstract: A method of manufacturing an artificial stone slab with veins comprises preparing a moldable hardenable fluid mixture of a first material (11); pouring the mixture into a mold (20) an upper face being exposed; engraving the exposed upper face with a predefined precise pattern of grooves (30) coinciding with a pattern of thin veins to be obtained; impregnating at least the inner faces (31) of the grooves (30) with a moldable hardenable fluid mixture of a second material (12), the color of both materials being different; causing the collapse and closure of the grooves, a visible pattern of thin veins of a second material with a natural look being left behind; curing the artificial stone slab by subjecting it to vibration, compression and vacuum until the fluid mixtures of the first material and of the second material are hardened.

Abstract: The present invention relates to a method of manufacturing an artificial stone slab with veins comprises preparing a moldable hardenable fluid mixture of a first material (11); pouring said mixture into a mold (20) an upper face being exposed; engraving the exposed upper face with a predefined precise pattern of grooves (30) coinciding with a pattern of thin veins to be obtained; impregnating at least the inner faces (31) of said grooves (30) with a moldable hardenable fluid mixture of a second material (12), the color of both materials being different; causing the collapse and closure of the grooves, a visible pattern of thin veins of a second material with a natural look being left behind; curing the artificial stone slab by subjecting it to vibration, compression and vacuum until the fluid mixtures of the first material and of the second material are hardened.

Abstract: A process for chemical cleaning of metal components having an iron oxide deposit upon a layer of compounds having a high silica content. The process includes the step of preparing an aqueous mixture including an agent for complexing Si(OH).sub.4 and at least one compound for dissolving the high silica content layer. The dissolving compound is selected from the group consisting of insertion compounds for inserting OH or F ions in the Si(OH).sub.4 and OH-containing organic compounds. The insertion compounds including electrophilic groups and are selected from the group consisting of conjugated unsaturated systems and unsaturated N-oxide compounds. The OH-containing organic compounds are selected from the group consisting of organic compounds having at least one alcohol function, aromatic amines, soluble salts of tertiary amines, and aromatic amines causing condensation of OH radicals onto silica.

Abstract: Repair of a steam generator tube is performed by crimping a tubular casing (18) in a zone (14) of the tube (12) in which a metallic coating (20) has been produced on the inner surface of the tube, for example by electrolytic deposition. The tubular casing (18) may consist of an attached sleeve (18), crimped in the tube (12). In the case of a tube crimped over only part of the length of the hole passing through the tube plate, the tubular casing may consist of the tube itself on which additional crimping is performed inside the hole which passes through the tube plate.