1I7 1

Cleaning non-corroding stainless steel

Cleaning stainless steel

Stainless steels are alloy steels with a chromium content of at least 10.5% and a carbon content of less than 1.2%.

A dense and chemically resistant layer of chromium oxide (passive layer) forms on the stainless steel surface in conjunction with oxygen. This resists many ag-gressive media and requires no further surface protection. The final treatment determines the quality of the stainless steel surface. Pickling gives the surface more of a matt appearance. Grinding and/or polishing results in glossy or high-gloss, reflective surfaces. Irrespective of the surface quality, all stainless steel surfaces are sensitive to fingerprints and hand prints, oily substances and adhesives etc.

• Do not stick any adhesive films, adhesive tapes, crepe strips etc. onto stainless steel surfaces for the purpose of temporary iden-tification. Often, the adhesives can only be fully removed with great difficulty or not at all, and leave behind unwanted marks and residues on the surfaces.

• Avoid welding and grinding of steel parts in the vicinity of stainless steel. Grinding sparks and weld splashes destroy the passive coa-ting and cause rust spots.

• Scouring media (e.g. steel scrapers, steel wool, steel brushes or steel sponges) must not be used.

• Acids, particularly acids containing chlorides, bleaches or silver polishing agents can pe-netrate or destroy the passive layer. Stainless steel must therefore not be cleaned with unsuitable agents.

Stainless-steel surfaces are hard, smooth and free of pores. No cavities for dirt and micro-organisms can therefore come into being. Nevertheless, even stainless steel components must be cleaned regularly and disinfected when necessary. Stuck-on dust and production residues must be removed carefully during the initial cleaning or basic cleaning. During surface cleaning, attention must be paid to the quality of the surface. Ground or polished surfaces can be wiped off wet, e.g. using a microfiber cloth. A sponge is often better on pickled surfaces. The type of dirt determines whether a cleaning agent is necessary. Simple dirt can be easily removed with stainless steel cleaners. Stainless steel cleaners loosen mineral dirt and lighten the surface without attacking the base metal.

Suitable care and cleaning agents are available from Hydro-Elektrik GmbH - see last page.

General

Surface cleaning

2I7 1

Cleaning non-corroding stainless steel

High-pressure cleaner Storage reservoir

Use of CARELA®-NOVOPUR with high-pressure cleaner

Light dirt deposits:

Storage reservoir

Pressure line - connection to cleaning system

Use of CARELA®-HYDRO-PLUS by use of separate acid-resistant pump

Heavy dirt deposits:

Using cleaning agents

Mineral deposits such as lime and cement residue, extraneous rust and also light oil and grease contamination can be effectively removed with E-NOX Clean. E-NOX Clean is a highly effective, ready-to-use cleaning gel that is used either undiluted or diluted, depending on the amount of dirt (can be diluted up to 1:10 with water). The water-based acidic cleaning gel contains biodegradable surfactants, is applied with a sponge or cloth and sticks very well to vertical surfaces thanks to its gel-like structure. This cleaning agent, which is suitable use where foodstuffs are present, can be removed using water and with no residue remaining.

Particularly in the water exchange zone, substances (lime, iron, manganese, organic mat-ter etc.) in the drinking water cause what are in some cases visually unattractive or un-hygienic surface deposits or discolouration on the inner surfaces of drinking water tanks. These deposits cannot be removed just by high-pressure flushing with water. In this case, it is necessary to employ chemical cleaning agents (disinfectant cleaners). Light dirt deposits, organic deposits: CARELA®-NOVOPUR, solution with neutral pH - min. exposure time 30 min Heavy dirt deposits, iron and manganese deposits: CARELA®-HYDRO-PLUS, undiluted, strong acidic solution - min. exposure time 30 min The media can be sprayed on. With existing cleaning systems, it is possible to spray directly with the high-pressure cleaner or using a separate low-pressure pump with the cleaning system (available as a supplementary set).

The final flushing with water is done with high pressure via the cleaning system. This removes all traces of the cleaning agent from both the cleaning system and inner surfaces. The flushing process must be continued until all flushing residue has been com-pletely removed. Flushing of the roof and, if necessary, the bottom is done with a spray lance or the special base/roof cleaning system.

Outer surfaces

Surfaces in contact with

water

3I7 1

Cleaning non-corroding stainless steel

A pickle cleaner may be required on damaged or very dirty surfaces. Pickle cleaners contain at least 25% phosphoric acid and small quantities of nitric acid and hydrofluo-ric acid. This composition enables even extraneous ferrites or tarnishing to be reliably removed. Thanks to its oxidising components, the pickle cleaner passivates the surface at the same time. Mechanical surface damage, extraneous rust or deeply embedded surface damage must be completely removed with abrasive fleece or by grinding and polishing in order to obtain a passive layer with long-term resistance. When using cleaners or abrasive fleece, for optical reasons it must be noted that due to the lightening effect, it is often necessary to treat the complete surface (risk of staining). Pickle cleaning should only be done by expert, trained persons.

Pickle cleaners are pasty and are applied with a sponge, brush or low-pressure spraying unit. Rubber gloves, acid-resistant protective clothing and tight-fitting goggles are re-quired for protection. Depending on the temperature and the amount of dirt, the ex-posure time is between 30 minutes and 2 hours. It must then be flushed off with water (ideally under high pressure). The pickle cleaner can be disposed of via the sewerage system. If necessary, it must be neutralised first. We recommend using DERUSTIT pickle cleaner 4023. Consumption is approximately 150 to 250 g/m².

Heavy surface damage or welds added later must be correctly treated locally with pickle paste. Pickling may only be done by trained persons and in accordance with the safety regulations.

Stainless steel surfaces, pipelines and containers can be done using e.g. hydrogen peroxi-de-based disinfectants or cleaning agents (e.g. Korasil). When disinfecting, pay attention to the required concentrations (standard disinfection 100 ml/m³, max. 120 mg/l) and exposure times. When using a high-pressure cleaner with a storage reservoir, the disin-fectant can be dosed directly into the storage reservoir. Disinfection is not normally required directly after a pickling process, provided that flus-hing has been performed at least three times using clean drinking water. Used pickling agents, cleaning agents and disinfectants must be disposed of correctly. Information about suitable mechanical and chemical cleaning agents can be found in the publication 824 of the „Non-corroding stainless steel“ information centre: www.edelstahl-rostfrei.de under Publications.

Pickle cleaner

Using pickle cleaners

Pickling with pickle paste

Disinfection

u:\pm\kata\i7i1\i7i1_cmyk_EN

Hydro-Elektrik GmbH • Angelestraße 48/50 • D-88214 Ravensburg • Tel.: +49 751 60 09 0 • Fax: +49 751 60 09 33

www.hydrogroup.de

09/2014

Cleaning non-corroding stainless steel

Stainless steel cleaning agents

The following cleaning agents are available directly from Hydro-Elektrik GmbH:

Designation Article No.

Hydro stainless steel care set 110800Contents:1 x bucket 10 l1 x microfiber cloth,1 x sanding fleece (grain 400)1 x sanding fleece (grain 1000)1 x E-NOX Clean highly-concentrated cleaner 0,5 l1 x pack of over-shoes (disposable shoes, 100 ea. per pack)Area of use:Cleaning external surfaces.

E-NOX Clean Highly-concentrated cleaner 0,5 l 205764E-NOX Clean Highly-concentrated cleaner 1 l 204437E-NOX Clean Highly-concentrated cleaner 10 l 204556Area of use:For removing tarnishing, extraneous rust, welding scale, water spots and other contamination on stainless steel surfaces.

Multi Clean Concentrated cleaning agent 1 l 201509Multi Clean Concentrated cleaning agent 30 kg 203451Area of use:Versatile, environmentally-friendly cleaning concentrate with good dirt removal properties.Optimum removal properties on oil and grease residues, stubborn deposits, resinification and other deeply- ingrained dirt..

Sanding fleecs 158 x 224 mm, grain 400 205843Sanding fleecs 158 x 224 mm, grain 1000 204275Area of use:For stubborn dirt and for removing corrosion, degreasing and matting metal surfaces.

Care spray for stainless steel 204276Can 400 mlArea of use:Removing dust, light surface dirt, fingerprints, grease residues and for surface care

Other media on request.

When using cleaning products, always pay attention to the manufacturer‘s informati-on and the safety instructions in the safety data sheet.