# The Simple Pressure Vessels (Safety) Regulations 2016, Paragraph 5: Steel vessels


Non-alloy quality steels must meet the following requirements—
(a) they must be non-effervescent and supplied after normalisation treatment, or in an equivalent state;
(b) the content per product of carbon must be less than 0.25% and that of sulphur and phosphorous must each be less than 0.05%
(c) they must have the following mechanical properties per product—
(i) the maximum tensile strength Rm, max must be less than 580 N/mm2;
(ii) the elongation after fracture must be:
if test pieces are taken parallel to the direction of rolling:
thickness ≥ 3 mm:
A
≥ 22%,
thickness < 3 mm:
A 80 mm
≥ 17%,
or, if test pieces are taken perpendicular to the direction of rolling:
thickness ≥ 3 mm:
A
≥ 20%,
thickness < 3 mm:
A80 mm
≥15%,
(iii) the average bending rupture energy (KCV) for three longitudinal test pieces at minimum working temperature must not be less than 35 J/cm2. Not more than one of the three figures may be less than 35 J/cm2, with a minimum of 25J/cm2. In the case of steels intended to be used in the manufacture of vessels the minimum working temperature of which is lower than - 10°C and the wall thickness of which exceeds 5 mm, this property must be checked.

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Source: https://www.legislation.gov.uk/uksi/2016/1092/schedule/1/paragraph/5 (the official version)
Page: https://openlegislation.uk/simple-pressure-vessels-safety-regulations-2016/schedule-1/paragraph-5
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.