Stainless Steel IBC Handling Guide
Transtore Stainless Steel IBC Containers
Video - Installation of a Split Leverlock Clamp Ring

Stainless Steel Material Gage Data:

Sheet stock from the rolling mill is available in several finishes. To protect the finish, a static adhering PVC film may be applied. DSM normally handles "2B bare" and grains or polishes the part after all perforation is completed.

Stainless Steel Surface Finishes

The surface of Stainless Steel is actually an extremely thin but stable and passive Chromium rich oxide film, on which Stainless Steel relies for its excellent corrosion resistance. The surface finish on Stainless Steel should therefore be developed and maintained to ensure this vital property, and also for the secondary reason of the pleasing aesthetic appearance of Stainless Steel.

The Standard Mill Surface Finished are laid down in Specifications (BS 1449, Part 4, and the Committee of Stainless Steel Producers, American Iron & Steel Institute).

The finished are designated by a system of numbers, and these are broadly described hereunder relative to the finishing operations employed. It should be remembered that different grades of Stainless Steel can result in a variation of visual appearance for the same finishing operation. The thickness can also have an effect, generally the thinner the material the smoother the surface finish.

The thicker gauge sizes of Stainless Steel are hot rolled. This is done at high temperatures and will always result in a scaled surface.

Stainless Steel Flat Product is supplied in the annealed i.e. fully softened condition.

This is also a high temperature operation and unless carried out in a very closely controlled inert atmosphere, will result in oxidation (scaling) of the surface.

The scale is usually removed by a pickling process, that is the removal of the scale by use of suitable acids, and the passivated by the use of Nitric Acid.

No 1 Finish
Plate is hot rolled, annealed, pickled and passivated. This results in a dull, slightly rough surface; quite suitable for industrial applications which generally involve the range of plate thicknesses. Grinding marks may be visible in isolated areas.

Some of the thinner thicknesses within the plate range are Cold Rolled; but Sheet, Coil and Strip gauges are produced by Cold Rolling, i.e. rolled without and heating of the material. Cold Rolling hardens the material, and the thinner sizes may have to be subjected to an intermediate anneal and pickle, or bright annealed, during the reduction of thickness to final gauge.

The starting material for Cold Rolling always has a No. 1 finish. Cold Rolled material is supplied with the following standard mill finishes.

No 2D Finish
A no. 1 Finish after being Cold Rolled, Annealed, Pickled and Passivated. This results in a uniform dull matt finish, superior to a No. 1 Finish.

Suitable for industrial application, and eminently suitable for severe deep drawing as the dull surface, (which may be polished after fabrication) retains the lubricant during the drawing operation.

No 2B Finish
A 2D Finish is given a subsequent light skin pass cold rolling operation between polished rolls.

This is the most common finish produced and called for on sheet material. It is brighter than 2D and is semi-reflective. It is commonly used for most deep drawing operations, and is more easily polished to the final finished required than is a 2D finish.

No. 3 Finish
This is a ground unidirectional uniform finish obtained with 80 - 100 grit abrasive.

It is a good intermediate or starting surface finish for use in such instances where the surface will require further polishing operations to a finer finish after subsequent fabrication or forming.

No. 4 Finish
This is a ground unidirectional finish obtained with 150 grit abrasive. It is not highly reflective, but is a good general purpose finish on components which will suffer from fairly rough handling in service (i.e. restaurant equipment).

The final surface is blemish free with a high degree of image clarity, and is the true mirror finish.

Characteristics of Stainless Steel Alloys

CLEANING OF STAINLESS STEEL

• Always attempt the mildest cleaning method first. Be patient - repeat it a fair number of times before resorting to the more severe cleaning methods.
  
• Routine Cleaning. Stainless Steel's best friends are quite simply soap, mild detergent or ammonia solutions in warm water, applied with a soft cloth or nylon sponge.
  
• Occasionally the use of the least coarse nylon scouring pad may be required. Rinse and dry with a soft cloth.
  
• Stainless steel articles are ideally suited for washing in a dishwasher. Only if cookware is heavily soiled is any prewashing required. (Note: Don't wash in dishwashers which have galvanized (Zinc Plated) components. Indelible stains can result on the surface of Stainless Steel).
  
• Such simple Routine Cleaning will easily remove normal soiling. Repeated application will often remove heavier soiling and stains will become less noticeable and may completely disappear.
  
• Cleaning - Moderate Soiling, Light Staining. Apply the mildest household abrasive cleaner, or a paste made from fine chalk or soda bicarb, using a soft cloth or a fine nylon scouring pad. A soft bristle brush may also be used. Rub the surface as softly as possible using long even strokes in the direction of the polished finish if this exists. Avoid using a circular rubbing action. Rinse well and wash as described under Routine Cleaning.
  
• Cleaning - Heavy Soiling, Heavier Staining. Presoak in warm/hot detergent or ammonia solution. If this does not sufficiently soften burnt food or carbon deposits, household caustic cleaners will have to be used. Follow by cleaning as for Moderate Soiling, Light Staining. Repeat if necessary.
  
• If this does not suffice final resort may have to be made to the use of both coarser abrasive cleaners and nylon scouring pads, but with the risk that the surface may become slightly affected. Follow by a thorough rinse and Routine Cleaning.
  
• It is usually only the inside surfaces of cookware that are heavily soiled. If the more severe cleaning methods therefore have to be used - take care - Do not apply them to the outside surfaces where they are not required.

General Problems and Corrective Action.
· Acids
Avoid contact. If accidental contact does occur rinse immediately and soak in ammonia or soda bicarb solution. Follow by Routine Cleaning.

· Bleaches
Avoid contact with concentrated or undiluted bleach. If accidental contact does occur rinse immediately and soak in ammonia or soda bicarb solution. Follow by Routine Cleaning.

· Carbon Deposits/Burnt Food
Treat as described for Heavy Soiling, Heavier Staining

· Fats, oils and grease
Wipe off heavy deposits with a soft cloth or paper towel. Presoak in warm detergent or ammonia solution. Follow by Routine Cleaning.

· Finger Prints
Use Routine Cleaning. If necessary first treat the marks with a soft cloth or paper towel dampened with alcohol (methylated spirits), or an organic solvent (ether, benzine). Minimise the re-occurrence by applying a wax based household polish to the dry, cleaned surface.

· Films
A dull, cloudy film, or a "rainbow film" develops after drip drying. These are respectively due to too much detergent, or oil/grease in the washing-up water. Re-wash as for Routine Cleaning using fresh, clean water.

· Heat Discoloration/tints
Ease of removal depends on the severity thereof. Repeated cleaning as for Moderate Soiling, Heavier Staining may prove successful. If not, use a 10% solution of Nitric Acid* together with a fairly course household abrasive cleaner applied as a paste by hard rubbing with a coarse nylon scouring pad. (Some alteration to the surface appearance will result from these severe cleaning operations). Acid treatment must be followed by rinsing in ammonia or soda bicarb solution, and Routine Cleaning.

· Labels
Peel off as much as possible. Soak well in warm water, rubbing periodically with a soft soapy cloth or sponge. If adhesive remains, dry and rub gently with alcohol or organic solvent.

Don't remove labels by scratching off with a blade, or rubbing with coarse abrasives.

· Leakage and Spillage
Remove by thorough washing down as soon as it occurs, or at short regular intervals.
· Oily Deposits in Coffee Pots/Urns

Use a thin paste of soda bicarb in hot water, and rub with a fine nylon scouring pad. Rinse and follow by Routine Cleaning.

· Rust Stains
Light, superficial brown staining can be removed by Routine Cleaning repeated regularly for a few days. Similarly, repeated cleaning as for Moderate Soiling, Light staining will remove darker stains.

Rust spots with a halo around them indicate that a fragment of ordinary steel has become embedded in the surface of the Stainless Steel. Dab and spot, keeping moist for 20 - 30 minutes, with a 10% solution of Nitric Acid* on an ear bud. Repeat this treatment until no reoccurrence of the rust spot occurs. Severe rust stains are best removed by swabbing the stain, keeping it moist for 15 - 20 minutes with a 10% solution of Nitric Acid*, repeating if necessary. Very severe stains will require hard rubbing with a paste of fine household abrasive and 10% Nitric Acid*, using a fairly coarse nylon scouring pad, Acid treatments must be followed by rinsing in ammonia or soda bicarb solution, and Routine Cleaning.

· Sterilization
Add the sterilizing solution in the strength as laid down in the instructions. Avoid overdosing or the addition of concentrated solutions in one large dosage. Do not leave the sterilizing solution in the equipment longer than necessary, especially under stagnant conditions.

· Tannin Stains
Use a thin paste of sodium carbonate (washing soda) in hot water, and rub with a fine nylon scouring pad. Rinse and follow by Routine Cleaning.

· Nitric Acid (HNO3)
Nitric acid is a "friendly" acid towards Stainless Steel and is the only mineral acid which should be used to clean stainless steel. Avoid contact of the acid with other metals, particularly the aluminum and copper bases on cookware. A 10% solution (1 part Nitric Acid added to 9 parts water) is usually used. It may be obtained from most chemists, who will make up the 10% solution. Concentrated Nitric Acid must be handled with care. Dilute 10% solutions are less dangerous, but it is advisable to wear rubber gloves and eye protection. If accidental skin contact occurs, wash well with lots of water. Mix and keep the solution in glass containers. Dilute extensively before flushing down the drain. Keep it out of reach of children.

Procedure for Leak-Proof Testing of an Intermediate Bulk Container

1. Seal all container apertures.
2. Pressurize the container to 2.9 psig using a regenerative air source.
3. Coat all the seams and joints with a soap and water solution. (Soap solution recommended is 4 oz of soap to 3 gallons of water.)
4. Pressure must be held for a period of time sufficiently long enough to assure detection of leaks, but no less than 5 minutes.
5. After completion of leak detection depressurize the container.

Note: Care should be exercised when working with pressurized containers as injuries can occur. 

Q: What is the difference between 304 and 316 stainless steel?

A: The "300" series, as they are referred to, contain basically the same amounts of iron, nickel, and chromium1. The advantage to 316 stainless steel is it contains additional molybdenum. The additional molybdenum offers more corrosion resistance than the 304.

Q: What does the "L" mean in 316L stainless steel?

A: An important item to note is that CPE Systems carries the "300L" series. The "L" indicates about half of the carbon found in the regular "300" series. This reduces the possibility of corrosion, cracking, and pitting due to welding.

Q: What is the best kind of gasket material and what type do I need?

A: There are several different types, all with different properties that fit different applications:

Silicone Rubber (SI) - SI provides excellent resistance to oxidizing agents, saline solutions, acid solutions, alkaline solutions, and vegetable and animal oils. SI is also good for temperatures from -80°C up to 250°C.

Ethylene-Propylene Diene Monomer Rubber (EPDM) - EP provides excellent resistance to ozone, ultraviolet rays, and heat. As well EP has a low water absorption and good steam proof capabilities. This particular elastomer has an excellent "memory" which means that it resists permanent deformation. It is good for temperatures from -40°C to 150°C.

Nitrile Rubber (Buna) (NBR) - Buna has a high stress resistance in regards to wear and deformation. Buna has a high resistance to petroleum derivatives, oils, and fats of all kinds. However, Buna is not recommended for applications coming into contact with aromatic and chlorinated hydrocarbons or polar liquids such as ketones, esters, alcohol, and mineral acids. NBR is good for temperatures ranging from -25°C up to 130°C.

Fluoridated Rubbers (Viton) (FTM) - Viton has a good resistance to all kinds of animal oils. Viton is also extremely resistant to acid and solvent corrosion as well as a wide range of chemicals even at high temperatures. Viton is a very expensive elastomer but should provide a longer life than the other elastomers and therefore should offer savings in maintenance. Viton is good for temperatures from -15°C up to 280°C.