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71027 SS Care&Cleaning l/o 6/15/01 2:10 PM Page 2

DESIGNER

HANDBOOK THE CARE AND

CLEANING

OF STAINLESS

STEEL

Stainless

The Value Option¨ 71027 SS Care&Cleaning l/o 6/15/01 2:10 PM Page 3

TABLE OF CONTENTS IN

Cle INTRODUCTION ...... 1 clos

WHAT IS STAINLESS STEEL ...... 1 eac the TYPES ...... 1 pha

FORMS AND FINISHES ...... 2 stai (roo CLEANING OF STAINLESS STEEL ...... 3 stai

Types of surface contaminants ...... 3 of c to p TYPES OF CLEANERS AND METHODS ...... 4 surf

EFFECTIVE CLEANING METHODS ...... 5 per is e CARE OF STAINLESS STEEL ...... 5 to c T LISTING OF STAINLESS STEEL pra AND TUBE MANUFACTURERS ...... 6 dur incl con that met gen surf han T that Acknowledgments clea met The Specialty Steel Industry are of North America (SSINA) use acknowledges that this new with handbook contains information req originally published by the app Committee of Stainless Steel Producers, American and The Specialty Steel Industry of the North Steel Institute, which no longer America (SSINA) and the individual exists. Current SSINA member companies it represents have made every companies were represented effort to ensure that the information on that committee. presented in this handbook is technically correct. However, neither the SSINA nor its The SSINA wishes to member companies warrants the accuracy of the information contained in this handbook acknowledge the contributions or its suitability for any general and specific of the Development use. The SSINA assumes no liability or Institute and its consultant, responsibility of any kind in connection with Technical Marketing Resources the use of this information. The reader is advised that the material contained herein (, PA) for help in should not be used or relied on for any preparing the contents of specific or general applications without first this handbook. securing competent advice. 71027 SS Care&Cleaning l/o 6/15/01 2:10 PM Page 4

INTRODUCTION WHAT IS STAINLESS STEEL

Cleanliness and stainless steel are Stainless steel is not a single alloy, but rather the name applies to a group of iron-based closely related and, in many applications, alloys containing a minimum 10.5% . Other elements are added and the each is dependent upon the other. In chromium content increased to improve the resistance and heat resisting the handling of , chemicals, properties, enhance mechanical properties, and/or improve fabricating characteristics. pharmaceuticals and in the use of stainless steel as a construction material There are over 50 stainless steel grades that were originally recognized by the American (roofs, wall panels, entry ways, signs, etc.), Iron and Steel Institute (AISI). Three general classifications are used to identify stainless stainless steel provides the degree steel. They are: of corrosion resistance that is necessary 1) Metallurgical structure. to prevent product contamination or 2) The AISI numbering system (200, 300 and 400 series numbers). surface rusting. However, stainless steel performs best when clean — cleanliness 3) The , which was developed by the American Society is essential for maximum resistance for Testing Materials (ASTM) and the Society of Automotive Engineers (SAE) to apply to corrosion. to all commercial and alloys. This handbook describes various The various types of stainless steel are detailed in a designer handbook, “Design practices for cleaning stainless steel Guidelines for the Selection and Use of Stainless Steel,” available from the Specialty during manufacture and in use. This includes methods for removing free-iron Steel Industry of North America (SSINA). Several other publications are also available, contamination on stainless steel surfaces including: “Stainless Steel Fabrication,” “Stainless Steel ,” “Stainless Steel that may have been picked up from Finishes,” “Stainless Steel Specifications,” and “Stainless Steel Architectural Facts,” tools; and for removing to mention a few. general accumulation of dirt, grime and surface stains that occur during normal ALLOY TYPES handling and exposure to the elements. The reader should keep in mind 304 is the basic chromium-nickel 316 offers more corrosion-resistance that there are few specific rules for a austenitic stainless steel and has through the addition of . cleaning procedure. Accordingly, the been found suitable for a wide range This grade is desirable where the methods discussed in this handbook of applications. It is the most readily possibility of severe corrosion exists, are suggestions. Each manufacturer or available in a variety of product forms. such as heavy industrial atmospheres user, after obtaining competent advice This grade is easy to form and fabricate and marine environments. with respect to their individual with excellent resistance to corrosion. 316L is the low version of 316. requirements, should select methods 304L is the low carbon version of appropriate to those requirements. 430 is a straight chromium ferritic 304. It is sometimes specified where stainless steel with lower corrosion extensive will be done. h resistance than the 300 series. It is principally employed for interior use. y

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FORMS AND FINISHES Table 1 CLASSIFICATION OF STAINLESS STEEL PRODUCT FORMS Tabl Item Description Dimensions Sheet, strip, plate, and bar forms are shown in Con Thickness Width Diameter or Size Hot Table 1. Sheet finishes are shown in Table 2. Sheet Coil and cut lengths: Bar product conditions and finishes are Mill finishes Nos. 1, 2D & 2B under 3/16” (4.76mm) 24” (609.6mm) & over — Pol. finishes Nos. 3, 4, 6, 7 & 8 under 3/16” (4.76mm) all widths shown in Table 3; Plate is shown in Table 4. Ann Strip Cold finished, coils or cut lengths under 3/16” (4.76mm) under 24” (609.6mm) — hea In addition to the common mill and polished Pol. finishes Nos. 3, 4, 6, 7 & 8 under 3/16” (4.76mm) all widths finishes, there are numerous special finishes Plate Flat rolled or forged 3/16” (4.76mm) & over over 10” (254mm) — used for architectural applications. Some of Bar Hot finished rounds, squares, the more delicate finishes require special octagons and hexagons — — 1/4” (6.35mm) & over Ann precautions when cleaning and the advice Hot finished flats 1/8” (3.18mm) to 1/4” (6.35mm) to — to h 8” (203mm) incl. 10” (254mm) incl. of the supplier should be obtained. Cold finished rounds, squares, The most common special finishes are octagons and hexagons — — over 1/8” (3.18mm) * ** shown in Table 5. Cold finished flats 1/8” (3.18mm) to 3/8” (9.53mm) to — 4 1/2” (114mm) 4 1/2” (114mm) Wire Cold finishes only: (in coil) *** Round, square, octagon, hexagon, and flat wire under 3/16” (4.76mm) under 3/8” (9.53mm) —

Pipe & Several different classifications, with differing specifications, are available. For information on standard Tabl Tubing sizes, consult your local Steel Service Center or the SSINA. Con Not considered “standard” shapes, but of potentially wide interest. Currently limited in size to Hot approximately 6 1/2” (165.1mm) diameter, or structurals.

Hot or h Table 2 STANDARD MECHANICAL SHEET FINISHES Hot Unpolished or Rolled Finishes: hea No. 1 A rough, dull surface which results from hot to the specified thickness followed by or p and descaling. Hot No. 2D A dull finish which results from cold rolling followed by annealing and descaling, and may perhaps get and a light roll pass through unpolished rolls. A 2D finish is used where appearance is not of primary concern. Hot No. 2B A bright, cold-rolled finish resulting in the same manner as No. 2D finish, except that the annealed and cold descaled sheet receives a final light roll pass through polished rolls. This is the general-purpose cold-rolled opt finish that can be used as is or as a preliminary step to . Hot Polished Finishes: trea No. 3 An intermediate polish surface obtained by with a 100-grit . Generally used where a and semifinished polished surface is required. A No. 3 usually receives additional polishing during fabrication. No. 4 A polished surface obtained by finishing with a 120-150 mesh abrasive, following initial grinding with coarser * S . This is a general-purpose bright finish with a visible “grain” which prevents mirror reflection. No. 6 A dull satin finish having lower reflectivity than No. 4 finish in a medium of abrasive and oil. It is used for architectural applications and ornamentation where a higher luster is undesirable, and to contrast with Tabl brighter finishes. Fin No. 7 A highly reflective finish that is obtained by buffing finely ground surfaces but not to the extent of completely Sel removing the “grit” lines. It is used chiefly for architectural and ornamental purposes. No. 8 The most reflective surface obtained by polishing with successively finer abrasives and buffing extensively Sw until all grit lines from preliminary grinding operations are removed. It is used for applications such as mirrors Eng and reflectors. Dis Ang Abr Sel Em Elec Epo Spu Pla

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Table 3 CONDITIONS & FINISHES FOR BAR CLEANING OF Conditions Surface Finishes* STAINLESS STEEL e Hot worked only (a) Scale not removed (excluding spot conditioning) Stainless need to be cleaned for (b) Rough turned** (c) Pickled or blast cleaned and pickled aesthetic considerations and to preserve corrosion resistance. Stainless steel is Annealed or otherwise (a) Scale not removed (excluding spot conditioning) heat treated (b) Rough turned protected from corroson by a thin layer of (c) Pickled or blast cleaned and pickled chromium oxide. Oxygen from the (d) Cold drawn or cold rolled (e) Centerless ground atmosphere combines with the chromium (f) Polished in the stainless steel to form this passive over Annealed and cold worked (d) Cold drawn or cold rolled chromium oxide film that protects from to high tensile strength*** (e) Centerless ground further corrosion. Any contamination of the (f) Polished surface by dirt, or other material, hinders m) * Surface finishes (b), (e) and (f) are applicable to round bars only. this process and traps corrosive ** Bars of the 4xx series stainless steels which are highly hardenable, such as Types 414, 420, 420F, 431, 440A, 440B and 440C, are annealed before rough . Other hardenable grades, such as Types 403, 410, 416 and agents, reducing corrosion protection. Thus, 416Se, may also require annealing depending on their composition and size. some form of routine cleaning is necessary *** Produced in Types 302, 303Se, 304 and 316. to preserve the appearance and integrity of the surface. Stainless steels are easily

Table 4 CONDITIONS & FINISHES FOR PLATE cleaned by many different methods. They Condition and Finish Description and Remarks actually thrive with frequent cleaning, and, Hot rolled Scale not removed. Not heat treated. unlike some other materials, it is impossible Plates not recommended for final use in this condition.* to “wear out” stainless steel by excessive Hot rolled, annealed Scale not removed. Use of plates in this condition is generally confined cleaning. The effect of surface/ or heat treated to heat resisting applications. Scale impairs corrosion resistance.* roughness, grain/pattern orientation, and Hot rolled, annealed or Condition and finish commonly preferred for corrosion resisting and designs that allow for maximum rain cleaning heat treated, blast cleaned most heat resisting applications. or pickled (exterior applications) should be considered. Hot rolled, annealed, descaled Smoother finish for specialized applications. and temper passed Types of surface contaminants Hot rolled, annealed, descaled Smooth finish with greater freedom from surface imperfections Dirt - Like any surface that is exposed to cold rolled, annealed, descaled, than the above. d the environment, stainless steel can get dirty. optionally temper passed Dirt and soil can consist of accumulated Hot rolled, annealed or heat Polished finishes: refer to Table 2. treated, surface cleaned dust and a variety of contaminates that and polished come from many sources, ranging from the wind to everyday use. These contaminates ser * Surface inspection is not practicable on plates which have not been pickled or otherwise descaled. will vary greatly in their effect on appearance and corrosivity and ease of Table 5 SPECIAL STAINLESS STEEL FINISHES removal. While some may be easily Finish Description removed, others may require specific ely Selective Polishing Selective polishing of unprotected areas to produce patterns cleaners for effective removal. It may be Swirl Swirl patterns obtained with grinding wheels or stainless steel wire brushes necessary to identify the contaminate or rs Engine Turn Rings, circles, or overlapping circles created with a CNC-operated machine experiment with various cleaners. Distressed Random scratch pattern covering entire surface Frequently, warm water with or without a Angel Hair Finer random scratch pattern gentle detergent is sufficient. Next in order Abrasive Blast Matte, uniform, blast media choice determines appearance are mild non-scratching abrasive powders Selective Etching Etching of selected surface areas to obtain a pattern such as typical household cleaners. These Embossing Raised patterns pressed into the stainless by rolling can be used with warm water, bristle Electrochemical Applied to cut sheets, numerous colors (also called INCO or light interference coloring) Paint Applied to coils, full range of colors brushes, sponges, or clean cloths. Sputtering Thin layer of a colored material applied to surface with colored and/or precious metals

Perforated Designs Simple or elaborate patterns 3 71027 SS Care&Cleaning l/o 6/15/01 2:10 PM Page 7

Ordinary brushes or steel Shop oil and Grease - Shop oils, which may not a problem on dull finishes, or those EF wool should be avoided as they may leave carry grease, grit and chips, surfaces finished with a coarse polishing particles embedded on the surface which commonly produce surface soiling after grit. The best preventative measure is to Job can lead to RUSTING. many shop operations. Greases and other avoid using abrasive cleaners unless Ro For more aggressive cleaning, a small contaminates may also soil surfaces in food absolutely necessary. When abrasives are amount of can be added to the preparation and many other household and needed, first experiment on an Fin scouring powder. commercial situations. These soils may be inconspicuous area. A “soft abrasive,” such Cleaning should always be followed by corrosive in themselves or may not allow the as pumice, should be used. Abrasives can

rinsing in clean hot water. surface to maintain passivity, and so permanently damage some colored and Stu When water contains mineral solids, periodic removal is a necessity. Initially, highly polished finishes. Advice should be and which leave water spots, it is advisable to soap or detergent and water may be tried or obtained from the finish supplier when wipe the surface completely with dry towels. a combination of detergent and water plus a cleaning special finishes. Many cleaners Fingerprints and Stains - Fingerprints and mild solvent. The removal of oil and grease from contain corrosive ingredients which require stains resulting from normal use in stainless steel parts by immersion in thorough post-clean rinsing with clean consumer and architectural applications are chemical solvents is frequently used with water; however, thorough rinsing is Gre Bu the most common surface contaminates. cold-formed or machined parts that are recommended for all cleaning procedures. Bak Fortunately, these usually affect only laden with lubricants. This process, in its Clean Water and Wipe - The simplest, safest, appearance and seldom have an effect on simplest form, consists of bringing liquid and least costly method that will adequately Gre corrosion resistance. They are easy to solvent into contact with the surface to be do the job is always the best method. remove by a variety of simple cleaning cleaned and allowing dissolution to take Stainless surfaces thrive with frequent *NO methods. Fingerprints are probably the place; for example, washing a surface with cleaning because there is no surface Om wi most troublesome marks to remove from the trichloroethylene or similar liquid or stirring a coating to wear off stainless steels. A soft batch of small parts in a container of cloth and clean warm water should always surface of smooth polished or bright Hou solvent. Non-halgenated solvents, such as be the first choice for mild stains and loose finished stainless steel. Fortunately, they into acetone, methyl alcohol, ethyl alcohol, dirt and soils. A final rinse with clean water can be removed with a glass cleaner or by and methyl ethyl ketone, benzene, isopropyl and a dry wipe will complete the process gentle rubbing with a paste of soda ash ma alcohol, toluene, mineral spirits, and and eliminate the possibility of water stains. (sodium carbonate) and water applied with wel turpentine work well. Solvent Cleaning - Organic solvents can be a soft rag. Once again, this should be abr Many of these solvents are widely used to remove fresh fingerprints and oils followed by a thorough warm water rinse. intro used as individual cleaners, but there are and greases that have not had time to There are several special surface finishes surf thousands of blended or compound cleaners oxidize or decompose. The preferred where fingerprints present special problems: abr on the market. Users are advised to contact solvent is one that does not contain , polished No. 6, etched, some abrasive par suppliers of solvents for information on their such as acetone, methyl alcohol, and blasted finishes, and light electrochemical pro applications on stainless steel. mineral spirits. There are many colors applied over satin or brushed finishes. mo compounded or blended organic cleaners (NOTE: there are several special finishes surf TYPES OF CLEANERS that are commercially available and attempt designed to withstand fingerprints: AND METHODS with to optimize both cleanability and safety embossed, swirl patterns, lined patterns, etc.). General Precautions of c attributes. Cleaning can be accomplished low In selecting cleaning practices, consider the by immersing smaller articles directly into ass possibility of scratching and the potential for the solvent, wiping with solvent-impregnated rins post-cleaning corrosion caused by cloths, or by sophisticated vapor or spray stat incompletely removed cleaners. Scratching methods. The wiping technique sometimes that can occur on a bright mirror finish by leaves a streaked surface. cleaners that contain hard abrasives, or even by “grit” in wash water. This is usually

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EFFECTIVE CLEANING METHODS CARE OF STAINLESS STEEL

Job Cleaning Agents* Comments The cleaner stainless steel can be kept while in storage, being processed or during Routine Cleaning Warm Water, Soap, Ammonia, Detergent Apply with sponge or soft cloth. Can be used on all finishes. use, the greater the assurance of optimum e corrosion resistance. Some tips on the care Fingerprints and Smears 3M Stainless Steel Cleaner and Polish, Provides barrier film to minimize Arcal 20, Lac-O-Nu, Lumin Wash, O’Cedar fingerprints. Can be used on all finishes. of stainless steel are listed below: ch Cream Polish, Stainless Shine 1) Use paper or other protective an wrapping on the surface of the Stubborn Stains 3M Stainless Steel Cleaner and Polish, Rub lightly, using dry damp cloth, in stainless steel until processing e and Discoloration Allchem Concentrated Cleaner, Samae, the direction of polish lines on the Twinkle, Cameo Cleaner, Grade FFF stainless steel. is complete.* or Grade F Italian Pumice, Whiting or talc, 2) Handle stainless steel with clean Liquid Nu Steel, Copper’s or Revere Stainless Steel Cleaner, Household Cleaners, Lumin gloves or cloths to guard against re Cleaner, Zud Restoro, Sta-Clean, Highlite, stains or finger marks. Allen Polish, Penny-Brite, Copper-Brite 3) Avoid the use of oily rags or greasy Grease and Blood Scotch-Brite Power Pad 2001, Easy-Off, Excellent removal on , all finishes. cloths when wiping the surface. s. Burnt-on or De-Grease-It, 4% to 6% hot solution Particularly useful where rubbing Baked-on of such agents as tri-sodium polyphosphate, is not practical. 4) Do routine cleaning of exposed st, 5% to 15% caustic soda solution surfaces. Buildings with window ely Grease and Oil Any good commercial detergent or Apply with sponge or soft cloth in washing systems can utilize this caustic cleanser. direction of polish lines. method to clean exterior panels. *NOTE: Use of proprietary names is intended only to indicate a type of cleaner and does not constitute an endorsement. 5) Where possible, after cleaning, Omission of any proprietary cleanser does not imply its inadequacy. All products should be used in strict accordance with instructions on package. rinse thoroughly with water. 6) Cleaning with -containing s Household Cleaners - Household cleaners fall or low in chloride. The cleaning method detergents must be avoided. se into two categories: detergent (non-abrasive) generally employed with these cleaners is to 7) Even the finest cleaning powders er and abrasive cleaners. Both are effective for apply them to the stainless surface and can scratch or burnish a mill-rolled many mild dirt, stain, and soil deposits, as follow by cloth wiping, or to wipe directly finish. On polished finishes, s. well as light oils such as fingerprints. The with a cleaner-impregnated soft cloth. In all rubbing or wiping should be done e abrasive cleaners are more effective but cases, the cleaned surface should be in the direction of the polish lines, introduce the possibility of scratching the thoroughly rinsed with clean water and NOT across them. surface. However, the degree of wiped dry with a soft cloth if water streaking 8) DO NOT USE SOLVENTS in closed abrasiveness will vary greatly with the is a consideration. spaces or while smoking. ne, particular product, and some brands will Commercial Cleaners - Many commercial produce noticeable scratching on only the cleaners compounded from phosphates, *Many adhesive-backed papers and plastic sheets or tape applied to stainless steel for most highly polished and some colored synthetic detergents, and alkalis are s protection “age” in fairly short periods of time surfaces. All of these cleaners vary widely available for the cleaning of severely soiled mpt and become extremely difficult to remove. with respect to their acidity and the amount or stained stainless surfaces. When used Manufacturers should be contacted of chloride they contain. A neutral cleaner with a variety of cleaning methods, these regarding information as to how long d low in chloride is preferred unless the user is cleaners can safely provide effective protective films or paper can be left in place. assured that the surface can be thoroughly cleaning. Manufacturers should be ted rinsed after cleaning. The fact that the label consulted and their recommendations y states “for stainless steel” is no guarantee followed whenever using cleaners of this es that the product is not abrasive, not acidic, kind. The general precautions stated above also pertain to these cleaners.

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