Steel sheet in sheets [German version]

Table of contents

General:
Product information
Packaging
Transport
  Container transport
  Cargo securing


Risk factors and loss prevention:
Temperature Odor
Humidity/Moisture Contamination
Ventilation Mechanical influences
Biotic activity Toxicity / Hazards to health
Gases Shrinkage / Shortage / Theft
Self-heating / Spontaneous combustion Insect infestation




Product information

Product name

German Bleche in Tafeln, Stahlbleche in Tafeln
English Steel sheet in sheets
French Tôles
Spanish Chapas
CN/HS number * 72 ff.


(* EU Combined Nomenclature/Harmonized System)



Product description

Metal sheets in sheets are flat products with a rectangular cross-section, the width of which is much larger than the thickness. A distinction is drawn between hot- and cold-rolled sheet.

Hot-rolled sheet in sheets is produced from semifinished products (slabs or billets), which are reduced to certain thicknesses by rolling and annealing and cut mechanically or by burning into rectangular or also other shaped sheets.

Cold-rolled sheet in sheets is produced by removing rust from hot-rolled sheet by "pickling" it in a weak acid solution, then washing, brushing, drying, oiling and unrolling the sheet and finally performing cold-rolling by passing the sheet through a reducing mill and cutting into rectangular or also other shaped sheets. Cold-rolled steel is a more highly finished product and has a smoother surface, greater dimensional accuracy (thickness, width, length) and greater strength.

Depending upon the material from which it is made, metal sheet is divided into the following groups:

Sheet made from carbon steels
Sheet made from alloy steels
Sheet made from nonferrous metals and their alloys
Bimetallic plated sheet, i.e. sheet produced by bonding together two different metals
Sheet with protective coatings, for example PVC or PE coated sheet or galvanized, tinned sheet

A distinction is also drawn between the following types:

Black plate (black iron sheet): hot-rolled, nondescaled sheet for second grade applications placing no particular demands on surface quality
Galvanized sheet: steel sheet with a zinc coating. The coating increases the utility value of the sheet. In order to improve the durability of the zinc coating, hot-dip galvanized sheets are reheated once more to approx. 600°C
Corrugated sheet: corrugated rectangular sheets produced by rolling. Their utility value is increased by subsequent galvanization
Electric steel sheet: thin steel sheet alloyed with silicon with special magnetic properties
Tinplate: steel sheet coated with tin
Terne plate: steel sheet with a lead-tin coating. Due to the toxicity of lead, such sheet cannot be used as a packaging material for food products
Stainless steel sheet (high-grade sheet): steel sheet made from alloy and nonalloy steel of high purity which is consequently nonrusting or resistant to heat or chemicals


Quality / Duration of storage

The value of steel products is in particular reduced by the effects of corrosion and mechanical damage.

One particularly frequent cause of damage is rust due to seawater, rain, condensation water in the means of transport, cargo sweat or condensation inside the packaging. Unsuitable means of transport, ships with poor hatch covers or without ventilation facilities, damaged containers, uncovered railroad freight cars and trucks, incorrect storage in the open, use of unsuitable tarpaulins, exposed loading in wet weather conditions, and variations in temperature and climatic conditions during long voyages may result in rust damage.

In the case of hot-rolled steel, it is usual to store it in the open and to transport it without protection, such that no protection is provided against rain etc.. Such sheet therefore generally exhibits a layer of surface rust (rust film). Since the rust is removed from the steel (by pickling) prior to further processing, the quality of the steel is not impaired. Protection should be provided from seawater or chemical residues because corrosion must remain within reasonable bounds, since pickling cannot remove uneven local corrosion or pitting corrosion.

Pickled and oiled hot-rolled sheet and cold-rolled sheet, together with hot-dip galvanized fine sheet, galvanized fine sheet (i.e. electrolytically coated sheet, for example plated with zinc tin etc.), electric steel sheet and tinplate should be protected from any kind of corrosion by selecting the correct type of packaging, warehousing and means of transport.

The degree of rusting of steel consignments should be recorded in the shipping documents before acceptance of the consignment, possibly using the following definitions:

Wet before shipment
Partly rust stained to rusty
Gear marked
Contaminated by foreign substance
Contaminated by saltwater
Chafed in places
Packing torn exposing contents


The AMERICAN RUST STANDARD GUIDES are mainly used to describe the condition of hot-rolled steel.

Packaged metal sheets should be provided with a wooden skid in order to prevent mechanical damage during storage and cargo handling. Unpackaged metal sheets should be stored on a flat surface supported with evenly spaced wooden dunnage (see Figure 4). Uneven surfaces and irregularly spaced wooden dunnage could crease or deform the sheet. Overstowing may also cause deformation.


Intended use

Hot-rolled steel is used e.g. for the manufacture of pipes, steel doors and tanks or is further processed into cold-rolled steel.

Much cold-rolled steel is processed in the automotive industry, but some is also used in the manufacture of household goods (e.g. fridges).

Galvanized sheet is used, e.g. in the automotive industry or in the production of roofing materials (e.g. flashing, guttering).

Tinplate is used in the packaging industry for the production of cans, for household goods and toys and for similar products.

Electric steel sheet is used, for example, in transformers, electrical machinery and equipment.

Stainless steel sheet is used, for example, in the manufacture of machinery, tools and containers.


Figures

(Click on the individual Figures to enlarge them.)

Figure 1

Figure 1
Figure 2

Figure 2
Figure 3

Figure 3
Figure 4

Figure 4



Countries of origin

Trade in steel and steel products primarily flows:

within the EU
Eastern block --> EU countries and USA
EU countries --> USA
Japan, Korea, India, South Africa, Brazil --> EU countries and USA


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Packaging

Hot-rolled sheets are held together in packages with steel strapping. In order to prevent movement of the sheets in transit and during storage, at least two steel straps are used in both the transverse and  longitudinal direction. An oxidation layer (scale), which provides limited corrosion protection, is formed on the surface of steel during hot-rolling or annealing. This layer is, however, highly sensitive and may easily flake off.

Pickled and oiled hot-rolled sheet and cold-rolled sheet, together with hot-dip galvanized fine sheet, galvanized fine sheet (i.e. electrolytically coated sheet, for example plated with zinc etc.), electric steel sheet and tinplate are provided with multilayer packaging in accordance with their quality, the route and duration of transport and frequency of handling.

Information about various packaging options may be found inter alia in.:

SIZ (German steel information center) instruction leaflet 474 "Packaging, storage and transport of fine sheet", 1st edition 1999, ISSN 0175-2006, publisher: SIZ, Sohnstraße 65, 40237 Düsseldorf


Examples of packaging for maritime transport:

1. Pickled and oiled hot-rolled sheet and cold-rolled sheet in sheets:

The sheets are first strapped together into packages with at least two steel straps in the transverse and longitudinal direction. The edges should then be covered with edge protectors made from e.g. paperboard, in order to protect subsequent layers of paper and film packaging from mechanical damage (creasing or tearing). Then, the first ply used is a fiber-reinforced packaging or plastic coated kraft paper, it being essential for the film-coated side to face outwards. In the case of unoiled cold-rolled sheet, a corrosion protection paper (e.g. VCI paper) should be used instead of the kraft paper. This part of the packaging is capable of binding any moisture which may form within the packaging. A plastic film (PE) of a minimum thickness of 150 µm should be used as the second ply. Alternatively, two plies of thinner films (e.g. 100 µm) may also be used. The edges must be provided with edge protectors (paperboard, plastic) in order to protect the film from mechanical damage. The third ply of the packaging consists of scrap sheet metal (hardboard elements may also be used for inland transport) on the side and end faces and on the top and bottom.  Finally, the package should be fastened onto a strong wooden skid (pallet made from nailed or screwed longitudinal and transverse lumber members) by at least two steel straps in the longitudinal direction and, depending upon length, with at last three steel straps in the transverse direction. The pallet or wooden skid should be sized such that the edges of the package do not stick out beyond it. The packages should finally be provided with identification tags and handling instructions. Such information includes shipping details, the "KEEP DRY" pictogram and the instruction "DO NOT UNWRAP UNTIL STEEL REACHES ROOM TEMPERATURE" (see Fig. 9).

2. Galvanized sheet in sheets: Packaging as in example 1, but not using a corrosion protection paper as the inner paper packaging as the corrosion protection agents could react with the galvanized surface. White bloom may occur on galvanized sheet even without direct exposure to external moisture due to the formation of condensation within the packaging due to temperature variations. This could be avoided by an additional ply of paper and/or by combined hardboard/sheet metal outer packaging.

3. Electric steel sheet in sheets: Packaging as in Example 1, but using a corrosion protection paper (e.g. VCI paper) as the inner paper packaging.

4. Tinplate in sheets: Packaging as in example 1, but not using a corrosion protection paper as the inner paper packaging as the corrosion protection agents could react with the tinned surface. Corrosion may occur on tinplate even without direct exposure to external moisture due to the formation of condensation within the packaging as a result of temperature variations. This could be avoided by an additional ply of paper and/or by combined hardboard/sheet metal outer packaging.

5. Stainless steel sheet in sheets: Internal packaging as in example 1, but using wooden boxes or crates as the outer packaging, as stainless steel sheets are often shipped in long sections and must accordingly be strongly packaged in the longitudinal direction (see Figure 8).


Figures:

Figure 5

Figure 5
Figure 6

Figure 6
Figure 7

Figure 7
Figure 8

Figure 8
Figure 9

Figure 9
Figure 10

Figure 10
Figure 11

Figure 11
 


Marking of packages
Mark07.gif (2224 bytes)

Keep dry
"DO NOT UNWRAP
UNTIL STEEL
REACHES ROOM TEMPERATURE"
TEMPERATURE"


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Transport

Symbols

Symbol, general cargo

General cargo



Means of transport

Truck, ship, railroad


Container transport

Standard containers are suitable for container transport of metal sheets.

The weight of the cargo should be uniformly distributed over the container floor area, while complying with the maximum weight in accordance with the CSC (Container Safety Convention) approval. The maximum line load must also be taken into account when loading containers (Container loading capacity).

Loads must be very carefully secured inside the container, since the packages of sheets must on no account be able to move.


Cargo handling

Cargo handling should be carried out in dry weather or under cover, since the product is highly susceptible to corrosion.

Figure 12

Figure 12


Packages of sheets must be handled carefully, especially when forklift trucks are used, owing to their sensitivity to mechanical damage. Damage may be prevented by correct handling and the use of suitable handling and slinging equipment (e.g. webbing slings, chain slings, tongs, clamps). 

Wood must be laid beneath individual sheets or packages without a wooden skid, so that they can be lifted without damage. 

The permissible loading capacity of the slinging and handling equipment and the lifting capacity of the load suspension equipment must also be taken into account.

Lifting or setting down the packages with excessive force results in distortion, which is detrimental to further processing.

In addition to purely mechanical damage to the product itself, damage to the packaging means that the product is no longer protected from moisture penetration. This may result in corrosion.


Stowage factor

0.47 m³/t (steel sheet, bundled) [1]
0.16 m³/t (shipbuilding plate, bundled) [1]
0.36 m³/t (steel sheet, package) [1]
0.22 m³/t (steel sheet, sheets) [1]
0.76 m³/t (galvanized sheet in solid wooden boxes) [1]
0.23 m³/t (corrugated sheet, package) [1]



Stowage space requirements

Due to its weight, this product is generally stowed in the lower hold. The loading capacity of the decks must be taken into account when drawing up the stowage plan.

The purpose of floor and interlayer dunnage is to protect the cargo and the means of transport from damage and to facilitate handling. Lateral dunnage is used where cargo handling has resulted in gaps in the stow. These gaps are either filled in during loading with squared lumber, planks or boards or subsequently closed by costly bracing (shoring).


Segregation

Oil-based paint (where necessary)


Cargo securing

Comply with the consignor's/manufacturer's loading instructions in order to avoid damage due to mechanical stresses.

Truck:

Packages must be transported in vehicles having a headboard and side walls (stanchions) with sufficient strength and loading capacity. Nonslip material must also be placed under the load and between layers. Gaps in the load are often unavoidable due to the handling methods used and vehicle characteristics (load distribution), so the load must be secured in accordance with anticipated accelerations by direct securing (e.g. tight fit, loop lashing) and/or by frictional securing (e.g. tie-down lashing).

For detailed information about cargo securing, see the chapters entitled Sheet metal and Sheet metal packages in the GDV Cargo Securing Manual.

For further information see also the chapters entitled

"Basic physical principles of cargo securing",
"Road vehicles, selection, equipping and loading capacity",
"Cargo securing materials".


Ship:

The following principles apply:

Select stowage spaces in accordance with the sensitivity of the cargo and anticipated accelerations
Where possible, load cargo closely against parts of the vessel or other cargo having sufficient loading capacity, but ...
... stow and secure in such a way that no excessive loads are applied to the hull or other parts of the vessel
Where possible, friction-enhancing materials should be laid beneath the cargo and between layers
Fill in any gaps between individual items of cargo
Protect cargo from chafing, scratching and similar mechanical damage
Protect cargo from harm caused by lashings and other securing materials
Heavy goods in particular, such as steel products, should where possible be stowed without gaps in a level layer from ship's side to ship's side


Railroad:

Packages must be transported in freight cars having a headboard and side walls (stanchions) with sufficient strength and loading capacity. Nonslip material must also be placed under the load and between layers. Gaps in the load are often unavoidable due to the handling methods used and freight car characteristics (load distribution), so the load must be secured in accordance with anticipated accelerations by direct securing (e.g. tight fit, loop lashing) and/or by frictional securing (e.g. tie-down lashing).


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Risk factors and loss prevention

RF Temperature

Steel sheet in sheets does not have any particular ambient temperature requirements for transportation and storage. It should however be noted that the temperature of the sheets determines whether the cargo sweats. Temperature variations may result in the formation of condensation within the packaging. 

Packages should thus display the following instruction: "DO NOT UNWRAP UNTIL STEEL REACHES ROOM TEMPERATURE".


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RF Humidity/Moisture

Steel metal requires particular humidity/moisture and possibly ventilation conditions (SC IV) (storage climate conditions).

Designation Humidity/water content Source
Relative humidity <40 - 50% [1]


Steel is a cargo which is at risk of corrosion. Corrosion losses are in particular caused by

Seawater and seasalt aerosols,
during maritime transport due to leaky containers or hatches
during storage at sea ports near water
Rain water,
when containers are damaged
uncovered railroad freight cars and trucks
incorrect storage in the open
use of unsuitable tarpaulins
exposed loading in wet weather conditions
Condensation water,
on the means of transport
on the cargo/load
within the packaging
Accompanying chemical cargo,
Residues of chemicals from previous cargoes, possibly combined with moisture,
Hygroscopic accompanying cargo (e.g. fresh lumber) and
Relative humidities > 40%.



Steel corrosion begins at a relative humidity of 40% and rapidly accelerates at relative humidities > 60%:

Figure 13

Figure 13


A distinction may be drawn between various Types of corrosion.

There are two main causes of corrosion:

Pure oxidation and
electrochemical decomposition of the metal due to the presence of an electrolyte (e.g. salts, acids, bases).


Pure oxidation means combination of the ferrous metal with atmospheric oxygen. Oxidation is assisted by electrochemical (electrolytic) processes. The extent of electrolytic decomposition is determined by the conductivity of the electrolyte present. For example, salt water is more conductive than fresh water and therefore has a greater corrosive effect. The effect of sulfurous acid is even more extreme.

If corrosion damage is suspected, testing is performed using the silver nitrate method, to find out whether chloride solutions or fresh water are the cause. When determining the origin of the sea salt on the cargo surface (corrosion resulting from contact with seawater or spray deposition by the hold/container air), the damaged surface is assessed with a magnifying glass (30x magnification): cubic sodium chloride (NaCl) crystals of an edge length of approx. 1/5 mm indicate contact with seawater. In the case of spray deposition, no crystal structures may be observed, since the crystals are too small (1/100 mm).

In the case of hot-rolled steel, it is usual to store it in the open and to transport it without protection, such that no protection is provided against rain etc.. Such sheet therefore generally exhibits a layer of surface rust (rust film). Since the rust is removed from the steel (by pickling) prior to further processing, the quality of the steel is not impaired. Hot-rolled sheets must also be protected from chloride solutions (e.g. seawater or fertilizer), since pickling cannot remove uneven local corrosion or pitting corrosion. Especially in the case of damage by salt water, the sheets should be rinsed off with fresh water as soon as possible after arrival with the receiver and then pickled because significant delay prior to pickling may have the above-stated consequences. For reasons of quality maintenance, the aim should always be to store, handle and transport the sheets in the dry.

Cold-rolled sheets are more sensitive to corrosion than hot-rolled sheets, such that not only cold-rolled steel, but also surface-treated hot-rolled steel is additionally packed, for example, in fiber-reinforced packing or plastic-coated kraft paper (montan paper) and plastic films. It is therefore important to keep moisture away at all times; unprotected storage in the open or unprotected cargo handling in wet weather should be avoided.

Figure 14

Figure 14
Figure 15

Figure 15



Galvanized or tinned sheet and electric steel sheet should be treated similarly to cold-rolled sheet, but no corrosion protection agents, such as VCI paper, should be used for galvanized and tinned sheet as such agents may react with the surface coatings. Moisture may, for example, give rise to a white bloom on the zinc coating. If rain or condensation water penetrates between the closely sheets of metal, the thin, protective zinc oxide layer does not form, but rather a thicker layer of pure zinc oxide. At the contact points between the sheets, this layer has the appearance of scurf.


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RF Ventilation

Steel sheet in sheets requires particular humidity/moisture and possibly ventilation conditions (SC IV) (storage climate conditions) .

Steel corrosion accelerates rapidly at relative humidity > 60%. If possible, relative humidity should be reduced to below 60% by appropriate ventilation measures.

However, the following should be noted:

  1. Steel exhibits a lower temperature than the external temperature anticipated during transit:

    If the temperature of the ambient air outside the ship rises, this has only a minimal effect on the temperature of the cargo. Ventilation with "warm" external air may result in cargo sweat on the "cold" steel, if the temperature of the latter is below the dew point of the ambient air. In such a case, ventilation may encourage corrosion.


  2. The steel is warmer than the external temperatures anticipated in transit:

    Ventilation may be performed without any risk of cargo sweat formation. However, cooling of the ship's sides may cause their temperature to drop below the dew point of the hold air, resulting in ship sweat inside the hold. In this case, the temperature of the hold air should be adjusted by ventilation to match that of the external air.



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RF Biotic activity

This risk factor has no significant influence on the transport of this product.


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RF Gases

Sulfur dioxides (exhaust gases from e.g. cargo handling equipment) have an extremely corrosion-promoting action on steel. It is therefore essential to prevent any contact with sulfur and its gases. Holds should accordingly be cleaned prior to loading.


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RF Self-heating / Spontaneous combustion

This risk factor has no significant influence on the transport of this product.


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RF Odor

This risk factor has no significant influence on the transport of this product.


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RF Contamination

Active behavior Sheet metal does not normally cause contamination. Corrosion protection agents may, however, contaminate other cargo.
Passive behavior Dust from coal, ores, salts and especially fertilizers and other bulk materials has a corrosive effect. For this reason, holds/containers have accordingly to be washed clean, to remove any residues from previous cargoes. When washing out ship holds with seawater, it must be borne in mind that seawater also contains salts which would encourage corrosion later in the voyage. It is therefore best to use fresh water for cleaning purposes.

The product should also be protected from acids, aggressive gases (sulfur dioxide) and readily decomposing chemicals, as these also accelerate corrosion.



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RF Mechanical influences

In order to avoid damage to pipes or their packaging by mechanical stresses, it is essential that stowing, cushioning, bracing, lashing and securing on the means of transport are performed carefully and in accordance with instructions. Suitable slinging and cargo handling equipment and lifting gear must be selected and used on the basis of the cargo's weight and slinging points.

If the strapping (steel straps) is damaged or broken, the packages loosen, resulting in an increased risk of damage. 

The main risk for sheet metal in sheets is creasing and tearing of the edges and corners. Bending is generally the result of handling with unsuitable handling equipment. If packaged sheet metal lies concavely and is overstowed, sagging must be expected. The edges of packaged sheet metal may crease, bend or be cut if they stick out beyond their wooden skid (see Figures 18 and 19).

Figure 16

Figure 16
Figure 17

Figure 17
Figure 18

Figure 18
Figure 19

Figure 19



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RF Toxicity / Hazards to health

This risk factor has no significant influence on the transport of this product.


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RF Shrinkage / Shortage / Theft

Depending upon the desirability of the product, either entire packages of sheets, including the means of transport, or only part of the consignment is/are taken.


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RF Insect infestation

This risk factor has no significant influence on the transport of this product.


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