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Unlike the standards for flat and long products, the standards for stainless steel tube products contain information on tolerances. This is possibly because the tolerance requirements for tubes are simpler to define.
|OD||Deviation from straightness on tube length L|
|> 33.7 mm||0.0020 L|
|< 33.7 mm||Agreed at time of enquiry and order|
Example 50mm dia tube x 6000 mm long maximum deviation from straightness = 12 mm
A tighter tolerance of 0.0015 L can be agreed at time of order and enquiry.
|OD||Tolerance on OD including ovality|
|< 168.3 mm||± 0.75 % or ± 0.3 mm whichever is the greater|
|> 168.3 mm||± 1.0 %|
A tighter tolerance can be agreed at the time of enquiry and order on tubes of < 114.3 mm of ± 0.5 % or ± 0.15 mm whichever is the greater.
For all tube sizes tolerance on wall thickness is ± 10 % or ± 0.2 mm whichever is the greater.
The outside weld bead of HF welded tube shall be removed completely i.e. flush with the outside surface of the tube.
The maximum heights of the external and internal weld seams shall otherwise be as given in the table below:
|Weld finish||Maximum height of weld seam|
|Wall thickness (T) < 8 mm||Wall thickness (T) > 8 mm|
|Finish A||0.20 T + 0.5||T/3|
|Finish B for D < 114.3 mm||0.06 T + 0.3||–|
|Finish B for D > 114.3 mm||0.05 T + 0.5||T/6|
Finish A – Internal and external weld bead not removed
Finish B – External weld bead removed internal weld bead not removed
Finish C – Internal and external weld bead rolled or removed
Finish A shall not be used on HF welded tube
|Type of length||Length L||Tolerance|
|Random||Length range by arrangement|
|Exact||< 6000 mm||+5/-0|
|6000 < L < 12000||+10/-0|