Molten Salt Baths - Code of Practice for the Safe Use of
This Code lays down the safety rules to be observed in any process in
which ferrous or non-ferrous metals - and sometimes other materials
such as rubber - are heat-treated in baths which contain molten salts.
The most common form of accident results from spattering of molten salt
when moisture enters the bath. The use of cyanides involves an obvious
toxicity hazard, and violent explosions due to overheating and decomposition
of nitrate salts have also occurred.
While the Code is primarily concerned with the prevention of accidents
due to these three hazards, it also establishes requirements for bath
construction, maintenance, location and heating. It sets out safety rules
to be observed by persons engaged in the process, and precautions for
the safe handling, storage and disposal of the various types of salts.
Table of Contents
Introduction
1.1 Nitrate Salt Baths
1.2 Cyanide Case-Hardening Baths
1.3 Neutral Salt Baths
1.4 Scope of the Code
1.5 Hazards involved in Salt Bath Heat Treatment
Definitions
2.1 Salt Bath
2.2 Catch Pit
2.3 Heat Treatment Terms
3. Storage of Salts
3.1 General Provisions
3.2 Containers
3.3 Placement of Nitrates in Storage
3.4 Special Provisions for Nitrate Containers
3.5 Placement of Cyanides in Storage
3.6 Handling and Transferring of Cyanides
4. Provisions Relating to Premises
4.1 Location and Isolation of Salt Baths
4.2 Accidental Entry of ‘Water
4.3 Flooring
4.4 Adequate Working Space
4.5 Nitrate Salt Spillages
5. Construction of Baths and Accessories
5.1 General Requirements
5.2 Bath Covers
5.3 Catch Pits
5.4 Quench Baths
5.5 Identification
6. Means of Heating
6.1 General Requirements
6.2 Temperature Control and Alarm Devices
6.3 Temperature Measurement Gauge
6.4 Additional Electric Heating Safeguards
7. General Precautions
7.1 Instruction and Supervision of Workers
7.2 Cautionary Notices
7.3 Instruction of Nightwatchmen
7.4 Fire Hazards to be Notified
7.3 Fire Fighting Equipment
7.6 Melting and Solidifying of Salts
8. Operating Rules
8.1 General Rules
8.2 Rules Pertaining to Nitrate Baths
8.3 Rules Pertaining to Cyanide Baths
9.1 Dredging
9.2 Examination
9.3 Salt Removal in Solid State
9.4 Salt Removal in Molten State
10. Disposal of Used Salts
10.1 Disposal of Used Nitrate Salts
10.2 Disposal of Used Cyanide Salts
11. Protective Clothing and Equipment
11.1 Provision to be Made
11.2 Laundry and Cleaning
11.3 Storage of Work Clothing
12. Responsibilities of Personnel
12.1 Obligations of Employers
12.1 Obligations of Workers
Appendix 1 First Aid Treatment of Cyanide Poisoning
Appendix 2 Disposal of Cyanide tastes
Appendix 3 Cyanide Spillages
Appendix 4 Types of Fire Extinguishers
