Number
284-EN
Section
General Section
Use
Sector
Manufacture of fabricated metal products, except machinery and equipment
General manufacturing, e.g. machinery, equipment, vehicles, other transport equipment
Function
Other
Process
Manual activities involving hand contact
Product category
Welding and soldering products, flux products
Application
Substituting Methanol and Borax
Abstract
One of Denmark’s largest manufactures of gold jewellery has successfully substituted the welding fuel agent Flux V, containing methanol and borax. It has been substituted with an acetone/hydrogen mixture. Apart from the benefits of eliminating boron and handling of methanol in the procedure, the lower flame temperature has made the precision welding procedure more manageable.
Substituted substances
Methanol
CAS No. 67-56-1 EC No. 200-659-6 Index No. 603-001-00-X
Chemical group
Alcohols
Classification: hazard statements
H225 Highly flammable liquid and vapour
H331 Toxic if inhaled
H311 Toxic in contact with skin
H301 Toxic if swallowed
H370 Causes damage to organs
Other adverse effects
The substance is: neurotoxic cat. 4 (Vela et al.) as listed in the Substance Database according to SUBSPORT Screening Criteria (SDSC).
Borax
CAS No. 1330-43-4 EC No. 215-540-4 Index No. 005-011-00-4
Chemical group
Borates, metaborates, tetraborates, peroxyborates
Classification: hazard statements
H360FD May damage fertility. May damage the unborn child
Alternative Substances
Acetone
CAS No. 67-64-1 EC No. 200-662-2 Index No. 606-001-00-8
Chemical group
Ketones
Classification: hazard statements
H225 Highly flammable liquid and vapour
H336 May cause drowsiness or dizziness
H319 Causes serious eye irritation
Hydrogen
CAS No. 1333-74-0 EC No. 215-605-7 Index No. 001-001-00-9
Chemical group
Inorganic gas
Classification: hazard statements
H220 Extremely flammable gas
Reliability of information
Evidence of implementation: there is evidence that the solution was implemented and in use at time of publication
Reason substitution
other toxic effects
skin/respiratory sensitizing
Hazard Assessment
Substances to be substituted: Borax is a Substance of very high concern and is included on the REACH candidate list for authorization, according to Article 59 of Regulation (EG) No. 1907/2006. (REACH Regulation). Methanol is a Substance of very high concern and is included on the REACH restriction list, according to Article 73 of Regulation (EG) No. 1907/2006. (REACH Regulation). Alternative substances: Acetone is not listed in the SUBSPORTplus Database.
Description of Substitution
One of Denmark’s largest manufactures of gold jewellery has successfully substituted the welding agent Flux V, containing methanol and borax. For precision welding in gold jewellery production a spit flame with a temperature of 2500°C is commonly used. The production manager was eager to find an alternative fuel than Flux V, not containing any boron compound in the flame, and came across a solution consisting of a mixture of acetone and hydrogen gas. In order to use the acetone/hydrogen mixture, investments in hydrogen generators and vessel and tubing capable of handling the higher vapour pressure of the acetone. (At 20°C: Methanol = 129 mbar, Acetone = 246 mbar). Hydrogen is being produced directly when needed, and acetone is only handled in amounts of approx. 0.5 L at the time, so the total amounts of accessible flammable agents are fairly limited. Apart from the occupational benefits from being rid of the methanol/borax solution, the acetone/hydrogen flame holds a temperature of 1850°C, making the welding process more manageable.
Case/substitution evaluation
This case exemplifies the possibility to use an alternative not reproductive toxicant mixture for precision welding in gold jewellery production.
State of implementation
In use
Enterprise using the alternative
Availability of Alternative
On the market
Type of information supplier
User
Contact
Date, reviewed
November 26, 2021