Steel sheet in coils
[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 Coils, Stahlbleche in Coils
English
Steel sheet in coils
French
Tôles
Spanish
Chapas
CN/HS number *
72 ff.
(* EU Combined Nomenclature/Harmonized System)
Product description
Metal sheets in coil form are flat products wound into rolls and having 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 coil form is produced from semifinished products (slabs or billets), which are reduced to certain thicknesses by rolling and annealing and wound into a roll.
Cold-rolled sheet in coil form 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 under pressure and winding it into a roll. 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 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.
In order to prevent mechanical damage during storage, high-grade coils should be stored individually on coil skids. Coils are mainly stored in the cantline in several layers. In this case, the coils must be prevented from rolling with wedges and friction-enhancing materials (e.g. nonslip mats) should be laid between the coils. The number of layers is dependent upon the dimensions and weight of the coils Overstowing may result in distortion.
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 2
Figure 3
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
Metal sheet is dispatched in coils weighing up to 50 metric tons.
Hot-rolled sheets of various thicknesses are packaged without packaging and strapped transversely with 5 – 8 steel straps and longitudinally with 1 – 5 steel straps. 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 , ISSN -, publisher: SIZ, Sohnstraße 65, Düsseldorf
VDI – The Association of Engineers‘ guideline VDI , part 1 „Packaging guideline for slit strip and coils of steel“
Examples of packaging for maritime transport:
1. Pickled and oiled hot-rolled coils/cold-rolled coils:
The coil is first secured with at least one steel strap in the transverse and longitudinal direction. The edges of the external and internal diameters of the coil 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 coils, 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.
Figure 5
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 paper and film should always be of a width such that they reach at least 30 cm into the coil eye on both sides. The edges of the external and internal diameters must be provided with edge protectors (paperboard, plastic) in order to protect the film from mechanical damage. In order to avoid damaging the first two layers of packaging, handling should be performed only with padded coil hooks (C hooks) or mandrels throughout the packaging operation.
Figure 6
The third ply of the packaging consists of scrap sheet metal (hardboard elements may also be used for inland transport) and covers the outer circumference, the end faces and the coil eye. The edges of the external and internal diameters should now be protected with sheet metal edge protectors, which are provided with water drainage holes.
Figure 7
Finally, the coil packaging should be held together by 6 steel straps in the transverse direction and 5 steel straps around the outer circumference. The steel straps also prevent the coil from telescoping. Seal protectors should be used under the seals for the circumferential steel straps (see Fig. 11). Coils must also 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. 8).
Where necessary, coils are also transported on wooden supports (coil skids) (see Figure 2).
2. Galvanized coils: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 coils 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.
3. Electric steel sheet in coils: Electric steel sheet is mainly transported with the coil eye upright („eye to the sky“). The coil is packaged in corrosion protection paper and film as in example 1 and placed on a bottom element of scrap sheet metal lying on a wooden support (special pallet or skid. The outer sheet metal packaging on the sides must overlap the bottom element from above. The sheet metal cover must likewise overlap the packaging on the sides. In this way it is impossible for any water running off the package to get inside. The coil should then be secured on the pallet with steel strapping. The pallet or wooden skid should be sized such that the edges of the coil do not stick out beyond it (see Figure 8).
Figure 8
4. Tinplate in coils: Packaging as in example 3, 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.
Further Figures:
Figure 9
Figure 10
Figure 11
Figure 12
Figure 13
Figure 13a
Figure 13b
Marking of packages
Keep dry
„DO NOT UNWRAP
UNTIL STEEL
REACHES ROOM TEMPERATURE“
TEMPERATURE"
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Transport
Symbols
General cargo
Means of transport
Ship, truck, railroad
Container transport
Standard containers
and „coiltainers“ (special container flatracks for heavy cylindrical loads) are suitable for containerized transport of coils.
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 coils 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 14
Figure 15
Figure 16
Figure 17
Figure 18
Figure 19
Coils must be handled carefully 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. C hooks, coil lifters, vertical coil lifters, coil mandrels, webbing slings, chain slings).
Lifting or setting down the coils with excessive force results in distortion, which is detrimental to further processing, since the coils can no longer be properly unwound and further processed.
The permissible loading capacity of the slinging and handling equipment and the lifting capacity of the lifting gear must also be taken into account.
Figure 20
The edges of the sheets may be dented or torn, any protective layers (e.g. zinc) may be damaged and lose their protective function.
Figure 20a
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
0.43 – 0.57 m³/t (coils, unpackaged) [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. When transporting steel coils, particular attention must be paid to ensuring that such dunnage is sufficiently large in area. If the dunnage is too small, the load is distributed over a smaller area, so increasing pressure, which may result in damage to the cargo and the means of transport. Dunnage must be oriented in accordance with the load-bearing components of the means of transport. Special floor or interlayer dunnage need not be used if the coils are already on wooden supports (coil skids).
If coils are secured with wedges to prevent rolling, care must be taken to produce the wedges such that the underside of the wedge (2) and inside of the wedge (1, the side facing the coil) are cut across the grain and the outside of the wedge (3, which is nailed) is cut with the grain.
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
.
Trucks:
Coils are generally only transported on vehicles with an appropriately sized coil trough. Care must be taken to ensure that coils are placed directly against the edge of the trough or that sufficiently strong, properly secured spacers are placed between the coil and the edge of trough. Lashings must also be passed through the coil eye to ensure lateral stability, while an additional tie-down lashing prevents the coil from „jumping“ (see Figure 21).
Figure 21
Figure 21a
Figure 21b
For detailed information about cargo securing, see the chapters entitled
Coils
and
Coil remnants in the GDV Cargo Securing Manual.
For further information see also:
„Basic physical principles of cargo securing“,
„Road vehicles, selection, equipping and loading capacity“,
„Cargo securing materials“.
VDI – The Association of Engineers provides instructions on coil securing on page 20 of guideline VDI „Load securing on road vehicles“.
Ship:
Steel sheet in coils is predominantly carried in „face stow“, i.e. with the winding axis of the coil lying in the longitudinal axis of the ship. Gaps may be avoided in the direction of the coil axis for example by using C hooks, coil lifters or forklift trucks. However, due to the differing axial lengths of the coils and the desire for flexibility in cargo handling and similar reasons, this tends to be theoretical possibility. In practice, relatively large batches of coils are stowed such that a good transverse connection is achieved side-to-side, while leaving gaps in the longitudinal direction.
Rolls of steel sheet are stowed from one side of the ship to the other with a longitudinally oriented axis on transversely laid wooden dunnage of a large area. All coils should be set down in a close-packed arrangement. Wedges should be inserted to prevent shifting of the coil during loading and unloading. Any voids should be shored or filled with squared lumber.
The aim when securing coils is to create a large, immobile block of coils in the hold. Lashing may be performed using conventionally processed steel rope, steel strapping or chains. Adequate edge protection must be provided if there is a risk of damage by the lashing materials. Smaller batches or individual coils may be set down in beds and secured by wedges, blocks or lashing.
Extract from the paper „Steel cargoes on board ocean-going ships“: Instructions for stowing and securing coils on ocean-going ships.
Further information may be found in Guidelines for the correct stowage and securing of cargoes for carriage in ocean-going ships, in particular appendix 6 „Correct stowage and securing of sheet steel coils“ (pages 14 and 15)
Figure 22
Figure 22c
Railroad:
Special articulated flat freight cars with cargo troughs or scalloped skids and telescopic roofs or tarpaulin covers are used for coil transport by railroad.
Loading guideline 1.3.1 published by DB Cargo provides instructions for loading coils on flatbed freight cars.
Figure 22a
Figure 22b
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Risk factors and loss prevention
RF Temperature
Steel sheet in coils 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 sheet in coils 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 23
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.
Figure 25
Figure 26
Figure 27
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 28
Figure 29
Figure 30
Figure 31
Figure 32
Galvanized or tinned coils 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 coils 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 tightly wound layers, a thin, protective zinc oxide layer does not form, but instead a thicker layer of pure zinc oxide. At the contact points between the sheets, this layer has the appearance of scurf.
Figure 33
Figure 34
Seen on Thyssen premises: Instructions for truck drivers
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RF Ventilation
Steel sheet in coils 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:
- 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.
- 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.
Figure 35
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 must 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 packages or their packaging by mechanical stresses, it is essential that stowing, 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, for example, the strapping (metal bands) is damaged or broken, the coils loosen and the inner turns telescope, resulting in an increased risk of damage. Loosened coils result in problems during cargo handling using coil tongs and during subsequent unrolling prior to further processing. Impurities (e.g. stones) which make their way into loosened coils cause damage to the surface if the turns are retightened.
Using wire ropes or chains for handling purposes may result in distortion to the edges of the coils.
Figure 36
Figure 37
Figure 38
Figure 39
Figure 40
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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 coils, 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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