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Tolerances to BS EN 10058 for hot rolled flat stainless steel bars

Introduction

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 flat bar tolerances to BS EN 10058, and covers thickness, width, length, straightness and ‘out-of-section’.

BS EN 10058:2018 superseded BS EN 10058:2003, which is withdrawn In comparison to the previous edition following technical changes were made:

  • Width of 130 and 140 mm were added for the flat bars
  • Wide flats were introduced in this standard with widths of 160, 170, 180, and 200 mm
  • For wide flats maximum permissible thickness variation was introduced
  • Standard was editorially revised

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.

Width, thickness , straightness and ‘out-of-section’

The table below, based on Table 2 of the standard, summarises width, thickness, straightness and ‘out-of-section’ deviations.

Width (b) Nominal width Limit deviation
between 10 and 40 +/- 0.75
over 40 up to 80 +/- 1
over 80 up to 100 +/- 1.5
over 100 up to 120 +/- 2
over 120 up to 150 +/- 2.5
Thickness (t) Nominal thickness Limit deviation
up to 20 +/- 0.5
over 20 up to 40 +/- 1
over 40 up to 80 +/- 1.5
Straightness (q) Nominal cross-section Tolerance in the plane
below 1000 mm2 below 0.4% of measuring length
1000 mm2 and above below 0.25% of measuring length
Out-of-section (u) Nominal thickness Tolerance
between 10 and 25 0.5
over 25 up to 40 1
over 40 up to 80 1.5
Thickness variation across width Nominal width Thickness variation
b > 150 =/- 0.5

Notes
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.

Length tolerances

The standard states ‘Depending on the type of length, flat 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

Notes
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 10058 specifies methods of measurement for the dimensional tolerances given. These are summarised below.

Width and thickness

Width and thickness must be measured at least 100mm from the end of the bar, and for determining variations in thickness, a line running perpendicular to the longitudinal axis of the product, at least 20mm from the longitudinal edges, is to be used.

Straightness

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.

Out-of-section

Out-of-section tolerance, u, applies to both nominal width, b and nominal thickness, t.

Maximum permissible variation in thickness across the width for wide flats
The variation in thickness across the width shall be determined along a line running perpendicular to the longitudinal axis of the product with the measuring points being at least 20 mm from the longitudinal edges and at least 100 mm from the ends of the bar.

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