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Tolerances to BS EN 10059 for hot rolled square stainless steel bars


Tolerances for hot rolled stainless steel bars are included with the general standards for hot rolled steel bars. The various sections are covered by:-
BS EN 10058 – Flat bars
BS EN 10059 – Square bars
BS EN 10060 – Round bars
BS EN 10061 – Hexagon bars

All of these can be used in conjunction with bars specified to BS EN 10088-3. This article covers square bar tolerances to BS EN 10059, and cover cross sectional, (edge or size), dimension, corner radius, length, straightness, twist, and ‘out-of-squareness’.
The data given is not intended to replace that shown in individual standards to which reference should always be made.
Dimensions and tolerances for stainless steel long products are covered in more detail in the BSSA special report ‘A Specifiers Guide to the New EN Standards for Stainless Steel Long Products’ available in the publications area of the web site.

Size, corner radius, straightness, twist and ‘out-of-squareness’

The table below, based on Table 2 of the standard, summarises size, corner radius, straightness, twist and ‘out-of-squareness’ deviations, (tolerances).

Size (a) Nominal size Limit deviation
between 8 and 14 +/- 0.4
between 15 and 25 +/- 0.5
between 26 and 35 +/- 0.6
between 40 and 50 +/- 0.8
between 55 and 90 +/- 1.0
100 +/- 1.3
between 110 and 120 +/- 1.5
between 130 and 150 +/- 1.8
Corner radius (r) Nominal size Radius
over 8 up to 12 up to 1
over 12 up to 20 up to 1.5
over 20 up to 30 up to 2
over 30 up to 50 up to 2.5
over 50 up to 100 up to 3
over 100 up to 150 up to 4
Straightness (q) Nominal size Tolerance in the plane
below 25 Not fixed
between 25 and 80 q up to 0.4% of L
over 80 q up to 0.25% of L
Twist Nominal size Tolerance
over 8 up to 14 4 degrees/metre, max of 24 degrees
over 14 up to 50 3 degrees/metre, max of 18 degrees
over 50 3 degrees/metre, max of 15 degrees
Out-of-squareness (u) Nominal thickness Tolerance
up to 50 1.5
over 50 up to 75 2.25
over 75 up to 100 3.00
over 100 up to 150 4.50

All dimensions are in mm. If agreed at the enquiry and order stage the limit deviations on size, (edge) can be all plus, minus zero, rather than equal plus / minus.

Length tolerances

The standard states ‘Depending on the type of length, square bars shall be cut to lengths within tolerances given in Table 3’. Table 3 categorises the type of length and notes that it is the purchaser’s responsibility to indicate at enquiry and order stages the type of length required and the length range or length required. No further explanation of the terms used in the standard is given. The table below is based on Table 3 of the standard.

Type of length Range Limit deviation
Manufacturing length, (M) 3000 to 13000 with a range of 2000 per order item 10% of bars may be below the minimum for the ordered range, but not less than 75% of the minimum of the range
Fixed length, (F) 3000 to 13000 +/- 100
Exact length, (E) below 6000 +/- 25
between 6000 and 13000 +/- 50

All dimensions are in mm.
If agreed at the enquiry and order stage, limit deviations (ranges) can be all plus, minus zero, rather than equal plus / minus.

Methods of measurement

BS EN 10059 specifies methods of measurement for the dimensional tolerances given. These are summarised below.




The size must be measured at least 100mm from the end of the bar.


The length must be measured as the longest length of the bar

Corner radius

The radius must be measured by a radius gauge at any point, at least 100mm from the end of the bar.




Straightness is measured as the maximum distance from a flat bed on which the bar rests to the underside of the “hogs back” shape of the bar. Straightness must be measured over the total length of the bar


The standard is not clear on the twist measurement method. The method is described as a distance difference, i.e. twist is measured with the bar on a horizontal surface with one side pressed against the surface. At the opposite end of the bar the difference in height of the two lower corners from the horizontal surface is measured. The tolerance is however expressed in degrees, i.e. as an amount of turn, not distance.




Out-of-squareness tolerance, u, is the deviation from the nominal size, a.

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