HazMat Tool — substance information

Hafnium powder, dry

HMT 15 June 2026

UN / ID: UN 2545
Hazard class: 4.2
Packing group: I (multiple — see tabs)
ERG guide: ERG 135
Special provisions: SP W31
Source: 49 CFR §172 (15 June 2026)

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Hafnium powder, dry

Hafnium is a chemical element; it has symbol Hf and atomic number 72. A lustrous, silvery gray, tetravalent transition metal, hafnium chemically resembles zirconium and is found in many zirconium minerals. Its existence was predicted by Dmitri Mendeleev in 1869, though it was not identified until 1922, by Dirk Coster and George de Hevesy. Hafnium is named after Hafnia, the Latin name for Copenhagen, where it was discovered. Wikipedia

Emergency Response Guide No. 135

Hazardous Materials Table

Source: 49 CFR §172 (15 June 2026)

Packing group I
Packing group II
Packing group III

(3) Hazard Class

4.2
Spontaneously combustible materials

(4) Identification number

UN 2545

(5) Packing Group

Comparison View of PG

(6) Labels

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.

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	242	see 49 CFR §173.242

(9) Quantity Limits

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

(10) Vessel stowage

(10A) Location

Stowage category “D” means the material must be stowed “on deck only” on a cargo vessel or on a passenger vessel carrying a number of passengers limited to not more than the larger of 25 passengers or one passenger per each 3 m of overall vessel length, but the material is prohibited on a passenger vessel in which the limiting number of passengers is exceeded.

Source: 49 CFR §172.101(k)

(10B) Other

13	see 49 CFR §176.84
148	see 49 CFR §176.84

Source: 49 CFR §176.84

(3) Hazard Class

4.2
Spontaneously combustible materials

(4) Identification number

UN 2545

(5) Packing Group

Comparison View of PG

(6) Labels

(7) Special Provisions (§172.102)

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

A20

Plastic bags as inner receptacles of combination packagings are not authorized for transportation by aircraft.

Browse special provision A20

IB6

_{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).
_{Additional Requirement:} Composite IBCs 11HZ2 and 21HZ2 may not be used when the hazardous materials being transported may become liquid during transport.

Browse special provision IB6

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

N34

Aluminum construction materials are not authorized for any part of a packaging which is normally in contact with the hazardous material.

Browse special provision N34

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

W31

Non-bulk packagings must be hermetically sealed.

Browse special provision W31

(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

Source: 49 CFR §172.101(k)

(10B) Other

13	see 49 CFR §176.84
148	see 49 CFR §176.84

Source: 49 CFR §176.84

(3) Hazard Class

4.2
Spontaneously combustible materials

(4) Identification number

UN 2545

(5) Packing Group

III

Comparison View of PG

(6) Labels

(7) Special Provisions (§172.102)

B135

For Large Packagings offered for transport by vessel, flexible or fibre inner packagings shall be hermetically sealed.

Browse special provision B135

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

IP21

When transported by vessel, flexible, fiberboard or wooden IBCs must be sift-proof and water-resistant or be fitted with a sift-proof and water-resistant liner.
Large outer packagings:
Large outer packagings:
§ 178.275(d)(2)
§ 178.275(d)(3)
§ 178.275(d)(2)
§ 178.275(d)(3)
Prohibited
§ 178.275(d)(2)
§ 178.275(d)(3)
Prohibited
Prohibited for liquids.
Prohibited
§ 178.275(d)(3)
§ 178.275(d)(3)
Prohibited
Prohibited
§ 178.275(d)(3)
§ 178.275(d)(3)
§ 178.275(d)(3)
§ 178.275(d)(3)
Prohibited
Prohibited
Prohibited for liquids. § 178.275(d)(2).

Browse special provision IP21

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

W31

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

Source: 49 CFR §172.101(k)

(10B) Other

13	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	Hafnium powder, dry	Hafnium powder, dry	Hafnium powder, dry
3	4.2	4.2	4.2
4	UN 2545	UN 2545	UN 2545
5	I	II	III
6	4.2	4.2	4.2
7	W31	A19, A20, IB6, IP2, N34, T3, TP33, W31	B135, IB8, IP21, T1, TP33, W31
8A	None	None	None
8B	211	212	213
8C	242	241	241
9A	Forbidden	15 kg	25 kg
9B	Forbidden	50 kg	100 kg
10A	D	D	D
10B	13, 148	13, 148	13, 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 1326	Hafnium powder, wetted with not less than 25 percent water (a visible excess of water must be present) (a) mechanically produced, particle size less than 53 microns; (b) chemically produced, particle size less than 840 microns	4.1