Test requirements

Steel shells

The materials used for the manufacture of shells and the weld beads shall, at their lowest working
temperature, but at least at -20 ºC, meet at least the following requirements as to impact strength:
- The tests shall be carried out with test-pieces having a V-shaped notch;
- The minimum impact strength (see 6.8.5.3.1 to 6.8.5.3.3) for test-pieces with the longitudinal
axis at right angles to the direction of rolling and a V-shaped notch (conforming to ISO R 148)
perpendicular to the plate surface, shall be 34 J/cm2 for mild steel (which, because of existing
ISO standards, may be tested with test-pieces having the longitudinal axis in the direction of
rolling); fine-grained steel; ferritic alloy steel Ni < 5%, ferritic alloy steel 5% ≤ Ni ≤ 9%; or
austenitic Cr - Ni steel;
- In the case of austenitic steels, only the weld bead need be subjected to an impact-strength test;
- For working temperatures below -196ºC the impact-strength test is not performed at the lowest
working temperature, but at -196 ºC.

Shells made of aluminium or aluminium alloy

The seams of shells shall meet the requirements laid down by the competent authority.

Shells made of copper or copper alloy

It is not necessary to carry out tests to determine whether the impact strength is adequate.

Impact-strength tests

For sheets less than 10 mm but not less than 5 mm thick, test-pieces having a cross-section of
10 mm × e mm, where "e" represents the thickness of the sheet, shall be used. Machining to 7.5 mm or
5 mm is permitted if it is necessary. The minimum value of 34 J/cm2 shall be required in every case.
NOTE: No impact-strength test shall be carried out on sheets less than 5 mm thick, or on their weld
seams.

(a) For the purpose of testing sheets, the impact strength shall be determined on three test-pieces.
Test-pieces shall be taken at right angles to the direction of rolling; however, for mild steel
they may be taken in the direction of rolling.
(b) For testing weld seams the test-pieces shall be taken as follows:
when e ≤ 10 mm:
three test-pieces with the notch at the centre of the weld;
three test-pieces with the notch in the centre of the heat affected zone (the V-notch to cross the
fusion boundary at the centre of the specimen);
 
when 10 mm < e ≤ 20 mm:
three test-pieces from the centre of the weld;
three test-pieces from the heat affected zone (the V-notch to cross the fusion boundary at the
centre of the specimen);
 
 

(a) For sheets, the average of the three tests shall meet the minimum value of 34 J/cm2 indicated in
6.8.5.2.1; not more than one of the individual values may be below the minimum value and
then not below 24 J/cm2;
(b) For welds, the average value obtained from the three test-pieces taken at the centre of the weld
shall not be below the minimum value of 34 J/cm2; not more than one of the individual values
may be below the minimum value and then not below 24 J/cm2;
(c) For the heat affected zone (the V-notch to cross the fusion boundary at the centre of the
specimen) the value obtained from not more than one of the three test-pieces may be below the
minimum value of 34 J/cm2, though not below 24 J/cm2.

If the requirements prescribed in 6.8.5.3.3 are not met, one retest only may be done if:
(a) the average value of the first three tests is below the minimum value of 34 J/cm2; or
(b) more than one of the individual values is less than the minimum value of 34 J/cm2 but not
below 24 J/cm2.

In a repeated impact test on sheets or welds, none of the individual values may be below 34 J/cm2.
The average value of all the results of the original test and of the retest should be equal to or more
than the minimum of 34 J/cm2.
On a repeated impact strength test on the heat-affected zone, none of the individual values may be
below 34 J/cm2.

Reference to standards

The requirements of 6.8.5.2 and 6.8.5.3 shall be deemed to have been complied with if the following
relevant standards have been applied:
EN 1252-1:1998 Cryogenic vessels - Materials - Part 1: Toughness requirements for temperature
below - 80 °C.
EN 1252-2:2001 Cryogenic vessels - Materials - Part 2: Toughness requirements for temperature
between - 80 °C and - 20 °C.

6.9

REQUIREMENTS FOR THE DESIGN, CONSTRUCTION, EQUIPMENT, TYPE APPROVAL, TESTING AND MARKING OF FIBRE-REINFORCED PLASTICS (FRP) FIXED TANKS (TANK-VEHICLES), DEMOUNTABLE TANKS, TANK-CONTAINERS AND TANK SWAP BODIES

NOTE: For portable tanks and UN multiple-element gas containers (MEGCs) see Chapter 6.7; for fixed
tanks (tank-vehicles), demountable tanks and tank-containers and tank swap bodies, with shells made
of metallic materials, and battery-vehicles and multiple element gas containers (MEGCs) other than
UN MEGCs see Chapter 6.8; for vacuum operated waste tanks see Chapter 6.10.

General

FRP tanks shall be designed, manufactured and tested in accordance with a quality assurance
programme recognized by the competent authority; in particular, lamination work and welding of
thermoplastic liners shall only be carried out by qualified personnel in accordance with a procedure
recognized by the competent authority.

For the design and testing of FRP tanks, the provisions of 6.8.2.1.1, 6.8.2.1.7, 6.8.2.1.13, 6.8.2.1.14
(a) and (b), 6.8.2.1.25, 6.8.2.1.27, 6.8.2.1.28 and 6.8.2.2.3 shall also apply.
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