HazMat Tool — substance information

Self-heating solid, toxic, inorganic, n.o.s.

HMT May 2026

UN / ID: UN 3191
Hazard class: 4.2
Packing group: II (multiple — see tabs)
ERG guide: ERG 136
Special provisions: SP IB5, SP IP2, SP T3, SP TP33
Source: 49 CFR §172 (2026/05)

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Self-heating solid, toxic, inorganic, n.o.s.

Emergency Response Guide No. 136

Hazardous Materials Table

Source: 49 CFR §172 (2026/05)

Packing group II
Packing group III

(3) Hazard Class

4.2
Spontaneously combustible materials

This entry is signed with "G". The letter "G" identifies proper shipping names for which one or more technical names of the hazardous material must be entered in parentheses, in association with the basic description. (See §172.203(k)).

(7) Special Provisions (§172.102)

×Note:
Special provisions may be very complex. The extracts are taken from 49 CFR §172.102. Please be careful with the information, as necessary, additional conditions may be applied that are not written here. Please check the original source and report bugs.

IB5

Authorized IBCs: Metal (11A, 11B, 11N, 21A, 21B, 21N, 31A, 31B and 31N); Rigid plastics (11H1, 11H2, 21H1, 21H2, 31H1 and 31H2); Composite (11HZ1, 21HZ1 and 31HZ1).

Browse special provision IB5

IP2

When IBCs other than metal or rigid plastics IBCs are used, they must be offered for transportation in a closed freight container or a closed transport vehicle.

Browse special provision IP2

Minimum test pressure (bar)	2.65
Minimum shell thickness	§ 178.274(d)(2)
Pressure-relief requirements	Normal
Bottom opening requirements	§ 178.275(d)(2)

Browse special provision T3

TP33

The portable tank instruction assigned for this substance applies for granular and powdered solids and for solids which are filled and discharged at temperatures above their melting point which are cooled and transported as a solid mass. Solid substances transported or offered for transport above their melting point are authorized for transportation in portable tanks conforming to the provisions of portable tank instruction T4 for solid substances of packing group III or T7 for solid substances of packing group II, unless a tank with more stringent requirements for minimum shell thickness, maximum allowable working pressure, pressure-relief devices or bottom outlets are assigned in which case the more stringent tank instruction and special provisions shall apply. Filling limits must be in accordance with portable tank special provision TP3. Solids meeting the definition of an elevated temperature material must be transported in accordance with the applicable requirements of this subchapter.

Browse special provision TP33

(8) Packing Authorizations (§173.***)

(8A) Exceptions	None
(8B) Non-bulk	212	see 49 CFR §173.212
(8C) Bulk	242	see 49 CFR §173.242

(9) Quantity Limits

(9A) Passenger aircraft/rail	15 kg
(9B) Cargo aircraft only	50 kg

(10) Vessel stowage

(10A) Location	C Stowage category “C” means the material must be stowed “on deck only” on a cargo vessel or on a passenger vessel. Source: 49 CFR §172.101(k)
(10B) Other	n/a

(3) Hazard Class

4.2
Spontaneously combustible materials

(4) Identification number

UN 3191

(5) Packing Group

III

Comparison View of PG

(6) Labels

Spontaneously combustible materials (4.2)

(1) Symbols

(7) Special Provisions (§172.102)

IB8

Authorized IBCs: Metal (11A, 11B, 11N, 21A, 21B, 21N, 31A, 31B and 31N); Rigid plastics (11H1, 11H2, 21H1, 21H2, 31H1 and 31H2 ); Composite (11HZ1, 11HZ2, 21HZ1, 21HZ2 and 31HZ1); Fiberboard (11G); Wooden (11C, 11D and 11F); Flexible (13H1, 13H2, 13H3, 13H4, 13H5, 13L1, 13L2, 13L3, 13L4, 13M1 or 13M2).

Browse special provision IB8

IP3

Flexible IBCs must be sift-proof and water-resistant or must be fitted with a sift-proof and water-resistant liner.

Browse special provision IP3

Minimum test pressure (bar)	1.5
Minimum shell thickness	§ 178.274(d)(2)
Pressure-relief requirements	Normal
Bottom opening requirements	§ 178.275(d)(2)

Browse special provision T1

TP33

Browse special provision TP33

(8) Packing Authorizations (§173.***)

(8A) Exceptions	None
(8B) Non-bulk	213	see 49 CFR §173.213
(8C) Bulk	242	see 49 CFR §173.242

(9) Quantity Limits

(9A) Passenger aircraft/rail	25 kg
(9B) Cargo aircraft only	100 kg

(10) Vessel stowage

(10A) Location	C Stowage category “C” means the material must be stowed “on deck only” on a cargo vessel or on a passenger vessel. Source: 49 CFR §172.101(k)
(10B) Other	n/a

Packing group comparison

Multiple packing groups apply to this entry. See assignment criteria in 49 CFR §173 Subpart D. Details are in the tabs above; differences are highlighted.

	PG II	PG III
1	G	G
2	Self-heating solid, toxic, inorganic, n.o.s.	Self-heating solid, toxic, inorganic, n.o.s.
3	4.2	4.2
4	UN 3191	UN 3191
5	II	III
6	4.2, 6.1	4.2, 6.1
7	IB5, IP2, T3, TP33	IB8, IP3, T1, TP33
8A	None	None
8B	212	213
8C	242	242
9A	15 kg	25 kg
9B	50 kg	100 kg
10A	C	C
10B	n/a	n/a

Segregation chart for load, transport, and storage

This chart shows whether loading, transport, or storage with other hazard classes is permitted, prohibited, or restricted. Based on 49 CFR §177.848.

Hazard class	8	7	6.1	5.2	5.1	4.3	4.2	4.1	3	2.3B	2.3A	2.2	2.1	1.6	1.5	1.4	1.3	1.1/1.2
1.1/1.2
1.3
1.4
1.5
1.6
2.1
2.2
2.3A
2.3B
3
4.1
4.2
4.3
5.1
5.2
6.1
7
8

	Must not be loaded, transported, or stored together in the same vehicle or facility.
	May be loaded, transported, or stored together.
	May be loaded, transported, or stored together only with restrictions.

Similar substances

UN / ID	Proper shipping name	Hazard class
UN 2793	Ferrous metal borings or Ferrous metal shavings or Ferrous metal turnings or Ferrous metal cuttings in a form liable to self-heating	4.2
UN 2968	Maneb stabilized or Maneb preparations, stabilized against self-heating	4.3
UN 3124	Toxic solids, self-heating, n.o.s.	6.1
UN 3095	Corrosive solids, self-heating, n.o.s	8
UN 3206	Alkali metal alcoholates, self-heating, corrosive, n.o.s.	4.2
UN 3209	Metallic substance, water-reactive, self-heating, n.o.s	4.3
UN 3128	Self-heating solid, toxic, organic, n.o.s	4.2
UN 3397	Organometallic substance, solid, water-reactive, self-heating	4.3
UN 3184	Self-heating liquid, toxic, organic, n.o.s	4.2
UN 3126	Self-heating solid, corrosive, organic, n.o.s	4.2
UN 3301	Corrosive liquid, self-heating, n.o.s	8
UN 3189	Metal powder, self-heating, n.o.s	4.2
UN 3185	Self-heating liquid, corrosive, organic, n.o.s	4.2
UN 3400	Organometallic substance, solid, self-heating	4.2
UN 3100	Oxidizing solid, self-heating, n.o.s.	5.1