HazMat Tool — substance information

Magnesium, powder or Magnesium alloys, powder

HMT 15 June 2026

UN / ID: UN 1418
Hazard class: 4.3
Packing group: I (multiple — see tabs)
ERG guide: ERG 138
Special provisions: SP A19, SP B56, SP W31
Source: 49 CFR §172 (15 June 2026)

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Magnesium, powder or Magnesium alloys, powder

Magnesium is a chemical element; it has symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point, and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic table), it occurs naturally only in combination with other elements and almost always has an oxidation state of +2. It reacts readily with air to form a thin passivation coating of magnesium oxide that inhibits further corrosion of the metal Wikipedia

Substance Data

Source: PubChem (HSDB, 04.12.2019)

CAS-Number

7439-95-4

Flash Point

n/a

Boiling Point

n/a

Emergency Response Guide No. 138

Hazardous Materials Table

Source: 49 CFR §172 (15 June 2026)

Packing group I
Packing group II
Packing group III

(3) Hazard Class

4.3
Dangerous when wet materials

(4) Identification number

UN 1418

(5) Packing Group

I

Comparison View of PG

(6) Labels

Dangerous when wet materials (4.3)

Spontaneously combustible materials (4.2)

Cargo Aircraft Only (Cargo Aircraft Only)

(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.

A19	Combination packagings consisting of outer fiber drums or plywood drums, with inner plastic packagings, are not authorized for transportation by aircraft. Browse special provision A19
B56	Water-tight, sift-proof, closed-top, metal-covered hopper cars are also authorized if the particle size of the hazardous material is not less than 149 microns. Browse special provision B56
W31	Non-bulk packagings must be hermetically sealed. Browse special provision W31

(8) Packing Authorizations (§173.***)

(8A) Exceptions	None
(8B) Non-bulk	211	see 49 CFR §173.211
(8C) Bulk	244	see 49 CFR §173.244

(9) Quantity Limits

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

(10) Vessel stowage

(10A) Location

A

Stowage category “A” means the material may be stowed “on deck” or “under deck” on a cargo vessel or on a passenger vessel.

Source: 49 CFR §172.101(k)

(10B) Other

13	see 49 CFR §176.84
39	see 49 CFR §176.84
52	see 49 CFR §176.84
148	see 49 CFR §176.84

Source: 49 CFR §176.84

(3) Hazard Class

4.3
Dangerous when wet materials

(4) Identification number

UN 1418

(5) Packing Group

II

Comparison View of PG

(6) Labels

Dangerous when wet materials (4.3)

Spontaneously combustible materials (4.2)

(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.

Combination packagings consisting of outer fiber drums or plywood drums, with inner plastic packagings, are not authorized for transportation by aircraft.

Browse special provision A19

Water-tight, sift-proof, closed-top, metal-covered hopper cars are also authorized if the particle size of the hazardous material is not less than 149 microns.

Browse special provision B56

_{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

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

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

Non-bulk packagings must be hermetically sealed.

Browse special provision W31

Non-bulk bags are not allowed.

Browse special provision W40

(8) Packing Authorizations (§173.***)

(8A) Exceptions	None
(8B) Non-bulk	212	see 49 CFR §173.212
(8C) Bulk	241	see 49 CFR §173.241

(9) Quantity Limits

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

(10) Vessel stowage

(10A) Location

A

Stowage category “A” means the material may be stowed “on deck” or “under deck” on a cargo vessel or on a passenger vessel.

Source: 49 CFR §172.101(k)

(10B) Other

13	see 49 CFR §176.84
39	see 49 CFR §176.84
52	see 49 CFR §176.84
148	see 49 CFR §176.84

Source: 49 CFR §176.84

(3) Hazard Class

4.3
Dangerous when wet materials

(4) Identification number

UN 1418

(5) Packing Group

III

Comparison View of PG

(6) Labels

Dangerous when wet materials (4.3)

Spontaneously combustible materials (4.2)

(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.

Combination packagings consisting of outer fiber drums or plywood drums, with inner plastic packagings, are not authorized for transportation by aircraft.

Browse special provision A19

Water-tight, sift-proof, closed-top, metal-covered hopper cars are also authorized if the particle size of the hazardous material is not less than 149 microns.

Browse special provision B56

_{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

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

Browse special provision IP4

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

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

Non-bulk packagings must be hermetically sealed.

Browse special provision W31

(8) Packing Authorizations (§173.***)

(8A) Exceptions	None
(8B) Non-bulk	213	see 49 CFR §173.213
(8C) Bulk	241	see 49 CFR §173.241

(9) Quantity Limits

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

(10) Vessel stowage

(10A) Location

A

Stowage category “A” means the material may be stowed “on deck” or “under deck” on a cargo vessel or on a passenger vessel.

Source: 49 CFR §172.101(k)

(10B) Other

13	see 49 CFR §176.84
39	see 49 CFR §176.84
52	see 49 CFR §176.84
148	see 49 CFR §176.84

Source: 49 CFR §176.84

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 I	PG II	PG III
1
2	Magnesium, powder or Magnesium alloys, powder	Magnesium, powder or Magnesium alloys, powder	Magnesium, powder or Magnesium alloys, powder
3	4.3	4.3	4.3
4	UN 1418	UN 1418	UN 1418
5	I	II	III
6	4.3, 4.2	4.3, 4.2	4.3, 4.2
7	A19, B56, W31	A19, B56, IB5, IP2, T3, TP33, W31, W40	A19, B56, IB8, IP4, T1, TP33, W31
8A	None	None	None
8B	211	212	213
8C	244	241	241
9A	Forbidden	15 kg	25 kg
9B	15 kg	50 kg	100 kg
10A	A	A	A
10B	13, 39, 52, 148	13, 39, 52, 148	13, 39, 52, 148

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 1869	Magnesium or Magnesium alloys with more than 50 percent magnesium in pellets, turnings or ribbons	4.1
UN 2950	Magnesium granules, coated, particle size not less than 149 microns	4.3
UN 1459	Chlorate and magnesium chloride mixture solid	5.1
UN 3407	Chlorate and magnesium chloride mixture solution	5.1
UN 1928	Methyl magnesium bromide, in ethyl ether	4.3
	Magnesium dross, wet or hot	Forbidden
UN 1419	Magnesium aluminum phosphide	4.3
UN 1622	Magnesium arsenate	6.1
UN 1473	Magnesium bromate	5.1
UN 2723	Magnesium chlorate	5.1
UN 2004	Magnesium diamide	4.2
UN 2853	Magnesium fluorosilicate	6.1
UN 2010	Magnesium hydride	4.3
UN 1474	Magnesium nitrate	5.1
UN 1475	Magnesium perchlorate	5.1