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Preferred thicknesses are shown and are intended to indicate which gauges are more likely to be available on an ex-stock basis from suppliers. Buyers of other thicknesses may be required to purchase full coil weight quantities.
Compared with the old British Standard tolerances, BS EN 10259 has the following differences:
The following is taken from the standard. It is not totally clear from the standard but the nominal widths defined in the table are the original rolled width not the slit width of the coil. All dimensions in mm.
|Nominal thickness||Normal tolerances for a nominal width w of||Special tolerances (S) for a nominal width w of|
|Equal to and over||less than||w<1000||1000<w<1300||1300<w<2100||w<1000||1000<w<1300||1300<w<2100|
1) Includes 6.50
Width tolerances are all positive, unlike the standards replaced that had equal plus and minus tolerances. BS EN 10259 has both ‘normal’ and ‘special’ ranges, the special tolerances being closest to those in the standards replaced, so if the ‘old’ width tolerances are required, then the BS EN 10259 special tolerances should be specified.
|Nominal thickness||Normal tolerances 1) for a nominal width w of||Special tolerances (S)1) for a nominal width w of|
|Equal to and over||less than||w<1252)||125<w<2502)||250<w<6002)||600<w<10002)||1000<w<21002)||w<125||125<w<250||250<w<600|
Length tolerances also have both ‘normal’ and ‘special’ tolerance ranges. ‘Special’ tolerance should be specifically requested. Each range is proportional to the length of the sheet or cut length, with a minimum tolerance at 2000mm length. Unlike the old standards, these tolerances apply for any length that can be supplied, and across the whole thickness range.
|Nominal Length L||Tolerances|
|L < 2000||+5/-0||+3/-0|
|2000 < L||+0.0025 x L/-0||+0.0015 x L/-0|
In contrast to the standards replaced, BS EN 10259 introduces tolerances for flatness of sheet, plate and cut lengths, with both a ‘normal’ and ‘special’ range. There is a larger tolerance range above 3000mm lengths. This greater tolerance also applies to strip, for which there is also a limitation of edge waviness.
The flatness tolerance of of strip, sheet/plate and cut length shall not exceed 10mm for normal cases and 7mm where a special tolerance (FS) is required for length < 3000mm and 12mm for normal cases and 8mm where a special tolerance (FS) is required for length > 3000mm.
For strip, the waviness of the edges, i.e. the ratio of wave height (h) to wave length (l) shall be max 0.03 for all thicknesses.
These requirements do not apply to work hardened material for which any requirement must be agreed between manufacturer and customer.
BS EN 10259 and the old British Standards take different approaches. The old standards specified that the nominal rectangular ordered dimensions (the ‘ordered format’) must be capable of being inscribed within the actual pieces supplied. BS EN 10259 allows this as an option, which may be specifically requested. If so requested, then the tolerances on width, length, out-of-square and edge camber can be re-negotiated. However, as the principal method of control, the EN defines the limit of out-of-squareness in two alternative ways, either through the difference in diagonal lengths, or by a direct measurement of the deviation from rectangular shape.
Option 1 – The out-of-squareness of sheets/plates and cut lengths shall not exceed 0.5% of the width of the product. Out of squareness is defined in Fig 2 below:
Option 2 – shall not exceed the values in the table:
All dimensions in mm
|Length L of sheet plate or cut length||Maximum difference in diagonal lengths|
|L < 3000||6|
|3000 < L < 6000||10|
In a similar way, the EN defines limiting edge camber of sheets, plates and cut lengths, measured over either a 1000mm or 2000mm length. The old standards did not specify edge camber limits. Edge camber is defined as shown in Fig 3:
|Specified Width||Edge camber tolerances for measuring length|
|equal to and over||less than||1000||2000|
BS EN 10259 has the following benefits over the requirements in the withdrawn BS 1501-3 and BS 1449-2: