TT11

For fixed tanks (tank-vehicles) and

demountable tanks used

exclusively for the carriage of

LPG, with carbon steel shells and

service equipment, the hydraulic

pressure test, may, at the time of

the periodic inspection and at the

request of the applicant, be

replaced by the non-destructive

testing (NDT) techniques listed

below. These techniques may be

used either singularly or in

combination as deemed suitable by

the competent authority, its

delegate or inspection body (see

special provision TT9):

– EN ISO 17640:2010 – Nondestructive

testing of welds –

Ultrasonic testing –

Techniques, testing levels and

assessment,

– EN ISO 17638:2009 – Nondestructive

testing of welds –

Magnetic particle testing, with

indications acceptance in

accordance with

EN ISO 23278:2009 –

Magnetic particle testing of

welds. Acceptance levels,

– EN 1711:2000 – Nondestructive

testing of welds –

Eddy current examination of

welds by complex plane

analysis,

– EN 14127:2011 – Nondestructive

testing – Ultrasonic

thickness measurement,

Personnel involved in NDT shall be

qualified, certified and have the

appropriate theoretical and practical

knowledge of the non-destructive

tests they perform, specify,

supervise, monitor or evaluate in

accordance with:

– EN ISO 9712:2012 – Nondestructive

testing –

Qualification and certification

of NDT personnel.

After direct application of heat such

as welding or cutting to the pressure

containing elements of the tank a

hydraulic test shall be carried out in

addition to any prescribed NDT.

NDT shall be performed on the areas

of the shell and equipment listed in

the table below:

Area of shell an d equipment	NDT
Shell longitudinal butt welds	100% NDT, using one or more of the following techniques: ultrasonic, magnetic particle or eddy
Shell circumferential butt welds
Attachments, manway, nozzles and opening welds (internal) direct to the shell
High stress areas of fastening doubling plates (over the end of the saddle horn, plus 400 mm down each side)
Piping and other equipment welds
Shell, areas that cannot be visually inspected from the outside	Ultrasonic thickness survey, from inside, on a 150 mm (maximum) spaced grid

Irrespective of the original design

and construction standard or

technical code used for the tank, the

defect acceptance levels shall be in

accordance with the requirements of

the relevant parts of EN 14025:2013

+ A1:2016 (Tanks for the transport

of dangerous goods – metallic

pressure tanks – design and

construction), EN 12493:2013 +

A1:2014 + AC:2015 (LPG

equipment and accessories – welded

steel tanks for liquefied petroleum

gas (LPG) – road tankers – design

and manufacture),

EN ISO 23278:2009 (Nondestructive

testing of welds –

magnetic particle testing of welds –

acceptance levels) or the acceptance

standard referenced in the applicable

NDT standard.

If an unacceptable defect is found in

the tank by NDT methods it shall be

repaired and retested. It is not

permitted to hydraulic test the tank

without undertaking the required

repairs.

The results of the NDT shall be

recorded and retained for the

lifetime of the tank.

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