T20 PORTABLE TANK INSTRUCTION T20
The general provisions of section 4.2.1 and the requirements of section 6.7.2 shall be met.
Minimum test pressure 10 bar
Minimum shell thickness (reference steel) 8 mm
Pressure-relief provisions A frangible disc preceding a spring-loaded pressure-relief device, or an approved relief device constructed of materials compatible with the load.
Bottom opening provisions Not allowed
Alternatives permitted T22

Special packing provisions:

TP2
The degree of filling prescribed in 4.2.1.9.3 shall not be exceeded.
TP4
The degree of filling shall not exceed 90% or, alternatively, any other value approved by the competent authority (see 4.2.1.16.2).
TP7
Air shall be eliminated from the vapour space by nitrogen or other means.
TP13
Self-contained breathing apparatus shall be provided when this substance is transported, unless no self-contained breathing apparatus, as required by SOLAS regulation II-2/19 (II-2/54), is on board.
TP25
Sulphur trioxide 99.95% pure and above may be transported in tanks without an inhibitor provided that it is maintained at a temperature equal to or above 32.5°C.
TP26
When transported under heated conditions, the heating device shall be fitted outside the shell. For UN 3176, this provision only applies when the substance reacts dangerously with water.
TP35
Portable tank instruction T14 may continue to be applied until 31 December 2014.
TP37

Portable tank instruction T14 may continue to be applied until 31 December 2016 except that until that date:

  1. for UN Nos. 1810, 2474 and 2668, T7 may be applied;
  1. for UN 2486, T8 may be applied; and
  1. for UN 1838, T10 may be applied.