Copper sheets and strips for buildings│Non metallic materials and metal roofing materials are treated by yamauchi-metal-en

Specialist trader of nonferrous metals and producer of metal roofing materials.

Copper sheets and strips for buildings

Copper sheets and strips for buildings(Mitsubishi Shindoh)

Standard: Copper sheet. JIS H3100 Phosphorous-deoxidized copper plate. (DCUP). C1220P-1/4H or 1/2H, Copper strip. JIS H3100. Phosphorous-deoxidized copper strip. (DCUR) C1220R-1/2H

Producer: Mitsubishi Materials Corporation
Certificate of incombustibility: Approved by Minister of Land, Infrastructure and Transport. NM-8595

Wide copper strip (Europe)

Standard: Wide copper sheet.　Standard: Copper strip. equivalent to JIS H3100. Phosphorous-deoxidized copper strip. Thickness: 0.3mm/0.35mm/0.4mm/0.5mm. Width: 1000mm
Country of origin: Europe

Properties of copper sheets/strips for buildings
Copper sheets are of oxygen-free, tough-pitch, or phosphorous-deoxidized varieties. Phosphorous-deoxidized sheets are used for roofing metal. Phosphorous-deoxidized copper is smelted using phosphorous so a miniscule amount of phosphorous remains. It is the best kind for bending and welding
Physical properties
The chart below compares the physical properties of metals used in roofs. It is important to distinguish the metals and their properties according to intended assembly and usage. With metals, a particular problem is their flexibility due to heat expansion. Copper is 1.4 times more flexible than iron, making it more or less the same as stainless steel, and is 70% as flexible as aluminum. In the height of summer the surface temperature of copper sheets reaches 80℃ making a difference of 90-100℃ with its winter temperatures. The heat expansion based on this temperature difference is 100 x 1.7 = 170mm. For example, a single batten seam of 100m will expand and contract by 170mm. The longest piece of copper plating is fixed at 6m and between 5-6m expansion is taken for this size variance for tiling.
According to Young’s modulus, which is the standard for stretching and bending, copper comes in at 60% of lead making it a fairly soft metal. While this makes it easy to work on, it also leads to change in its shape due to expansion and contraction and external force. It is 3/4 as hard as iron and half as hard as stainless steal meaning the surface can be damaged during assembly – care must be taken during any work performed on the metal.

Properties of metals

Property

Copper

Aluminum

Zinc

SUS304

Relative density

8.94

2.70

7.86

7.93

Linear rate of expansion (mm/100ｍ/℃)

1.7

2.4

1.2

1.7

Rate of heat conduction (W/ｍ・℃)

385

138

Specific heat (J/g・℃)

0.38

0.96

0.48

0.5

Yield point (N/㎟)

137

216

264

235

Young’s modulus(104N/㎟)）

７

Tensile strength (N/㎟)

245

343

588

Shear resistance(N/㎟)

196

294

490

Hardness(Hv)

100

150

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Chemical properties

Chemical properties of copper
The extent of discoloring of copper
Before work is performed on them, copper sheets have a reddish-orange color, but upon contact with the atmosphere, this turns brownish due to cuprous oxide and oxidized copper forming and this color gradually becomes darker. When it rains after any work the color changes easily and the color of the extremely thin film formed on the surface is affected. This means that the composition of the copper may be questionable and there may be unusual oxidation. This an ageing process and generally the change in color will settle down after 3-6 months. After this, a green color gradually starts to appear due to the effects of rain and the environment. Eventually, after many years, basic (i.e. not acidic) carbonate and basic copper chloride are compositely formed and this becomes a delicate protective film. Oxidized copper has different colors depending on its variety and the oxidized form differs depending on the environment and surroundings and the slope and positioning of the roof. Thus, the same roof differs in parts and is not even. Not all copper plates have the same color changes and the natural environment and the condition of the building largely control the change. Below are the typical color changes.
Reddish orange – brown – dark brown – blackish brown – blue-green
Time of assemblyTwenty years later

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Copper’s resistance to chemicals
The chart below shows copper’s resistance to chemicals. Copper is weak to ammonia and ammonia compounds, sulfur, hydrogen sulfide and mercury, and is drenched by nitric acid and concentrated nitric acid. The risk of corrosion is greatly increased in hot spring areas with hydrogen sulfide and sulfur gas and near smoke-producing facilities that burn heavy fuel containing sulfides at high temperatures.

Chemical resistance of copper
Item	Corrosion	Item	Corrosion	Item	Corrosion
Alcohol	A	Mercury	D	Sulfur (dry)	B
Ammonia (wet)	D	Natural gas	B	Sulfur (soluble)	D
Ammonium hydroxide	D	Nitric acid	D	Sulfur dioxide (wet)	B
Ammonium chloride	D	Nitrogen	A	Sulfuric acid	B
Ammonium nitrate	C	Oxygen	A	Sulfurous acid	B
Ammonium sulfate	C	Sea water	B	Tar	A
Carbonated water	B	Sewage	A	Varnish	A
Carbon Dioxide	B	Soapy water	A	Drinking water	A
Chlorine	C	Sodium chloride	B	Factory conditions	A
Hydrogen	A	Water vapor	A	Sea water conditions	A
Hydrogen sulfide (wet)	D	Vinegar	B	Rural conditions	A

A: Complete resistance – no corrosion. B: Can be used with no problem, under partial conditions. C: Can be used in partial conditions but is corroded. D: Inappropriate for use

When it rains on copper roofs, the copper is partly ionized and this copper ion dissolves in the rain water. When this copper ion comes into contact with concrete or mortar, these alkalis react and become copper hydroxide and dye the mortar and concrete green. If the ions fall onto rocks they absorb carbonic gas, become copper carbonates and dye the rock green. It is important to take precautions on the external walls and under the eaves of the building if roof bypasses gutters and falls directly to the ground,

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Electric corrosion

When the electric potential of metals is different and they come into contact through water, electrons are exchanged and the metals become like a battery. This phenomenon is called electric corrosion and the metals are greatly corroded according to their potential difference.
The chart shows metals in order of electric potential . As is shown below, the electric potential between copper and stainless steel is small and there is no electric corrosion. In recent years, the nails used in copper roofs have mostly been made of stainless steel.

Galvanic series

US316 Stainless steel

SUS304 Stainless steel

Monel metal

Nickel

Copper

Aluminum bronze

Bronze

Tin

Lead

Tin solder

Cast iron

Soft iron

Aluminum compound　2014

Aluminum compound　2017

Cadmium

Aluminum compound　5052

Zinc-coated steel

Zinc

Magnesium

Reference: Nihon Shindoh Cooperation. Shindoh product data book

LinkIcon Mitsubishi Materials Corporation HP

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Durability of copper sheets

Holes opening in copper sheets

Photo1
It has been told for many years that holes appear in copper sheets when they corrode in acid rain. However, this phenomenon is limited to copper gutters on tiled roofs and parts where tiles and copper sheets touch in thatched-style roofs. It is thought that the reason for this is not inly rainwater concentrated in the center of tiles but also a height difference; the oxidized film that forms is detached and a new film is not formed (erosion). (Refer to photo 1) Further, there is thought to be a large effect caused by elution from the tiles and glazes. If this copper corrosion is due to acid rain, roofs made of straight slating with whole copper sheets should also have holes. Photo 2 is of the rooftop structure of the copper sheet roof of the central public hall in Osaka, renewed in 2002. The roof is 80 years old, having been laid in 1918 with a thickness of 0.35mm. It is surrounded by stable natural greenery and was not corroded at all. Thus, roofs entirely made of copper sheets do not undergo this hole-opening phenomenon. Based on this, it is thought that corrosion is due to usage rather than acid rain. Preventive measures for this include double-layered sheets where they touch tiles and assembly methods that increase the thickness of the sheets.　　
Photo 2Example of thatched-style roofing

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Durability of copper roofing against acid rain.

In the third investigation into acid rain in Japan (carried out between 1994-1998), the PH was observed as PH4.8-PH4.9 (national average over the year). Acid rain is rain under PH5.6 and most copper elution takes place around PH4 with its peak at PH3.5. However, at PH5 there is next to no elution. The chart below shows the results of an investigation of copper decreases in 48 places around the world carried out in the four years between 1986-1989 by the corrosion working group of the International Organization of Standardisation. It would take around 250 years for a 0.35mm thick sheet to decrease to 0.2mm based on Tokyo reduction figures. In Okinawa, the harshest area in Japan, it is estimated that it would take 65 years.

Reduction in copper / (48 places around the world: 4 year average for 1986-89)　

Reduction in copper / (48 places around the world: 4 year average for 1986-89)
Tokyo	0.0006㎜/year
Places with concentrated sulfuric acid (3-14 times that of Tokyo)	0.0014～0.0033㎜/year

Reduction in copper / (48 places around the world: 4 year average for 1986-89)
Okinawa	0.0023㎜/year
Places with concentrated chlorine (2-6 times that of Tokyo)	0.0017～0.0031㎜/year

Taken from the Japan Copper Centre data

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Copper sulfide sheets

Copper sulfideexample assembly

These are copper sheets created by artificially using oxidized chemical coloring on blackish-brown copper sheets using Potassium sulfate solution. This is easily affected by the atmosphere and rain, unlike dye, and is a surface treatment that gradually changes from blackish-brown to the natural greenish-blue over time.

Copper sulfide sheets, standards chart
Thickness(mm)	Width(mm)	Length(mm)
0.30	365	1212
0.30	455	1212
0.35	365	1212
	455	1212
	606	1212
0.40	365	1212
	455	1212
	606	1212
0.50	365	1212
0.50	455	1212

Note 1: All copper sulfide sheets are made on commission.
Note 2: Copper sulfide sheets may have a certain amount of color spotting due to their coloring being chemical; this spotting will become less conspicuous over time.
Note 3: Due to the nature of the surface film of copper sulfide sheets, the film may separate from the part that is worked on when bending the sheets. This filmless part will become less conspicuous over time.

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Stock list

Copper sheets

Copper sheet shipping/packaging status(For the domestic market)

Stock list of copper sheets for buildings
Thickness (mm)	Size (mm)	Weight (kg/sheet)	Sheets/package
0.25	365ｘ1212	1.00	40
0.30	365ｘ1212	1.20	40
0.30	455ｘ1212	1.49	30
0.35	365ｘ1212	1.39	30
	455ｘ1212	1.74	30
	606ｘ1212	2.29	15
0.40	365ｘ1212	1.59	30
	455ｘ1212	1.99	20
	606ｘ1212	2.62	15
	1000ｘ2000	7.20
0.50	365ｘ1212	1.99	20
	455ｘ1212	2.48	20
	1000ｘ2000	9.00

Copper strips (small coils)

Copper strip shipping/packaging status(For the domestic market)

Stock list of copper strips for building
Width(mm)	Thickness(mm)	Length(mm)	Enacted weight （ｋｇ）
182	0.30
	0.35
	0.40
227	0.30
	0.35
	0.40
303	0.30	60	48.6
	0.35	50	47.3
	0.40	45	48.6
305	0.30
	0.35
	0.40
365	0.30	50	48.8
	0.35	40	45.6
	0.40	35	45.6
	0.50
455	0.25
	0.30	40	48.7
	0.35	35	49.7
	0.40	30	48.8
	0.50
500	0.30
	0.35
	0.40
606	0.30	30	48.7
	0.35	25	47.4
	0.40	20	43.4
1000	0.30	20
	0.35	20
	0.40	20
	0.50	15