Number

439-EN

Section

General Section

Use

Abstract

Chromium trioxide was placed on the REACH Authorisation List in 2013 and its use has needed a specific authorisation in the EU since 2017.
Instead of preparing for reapplying for an authorisation to further use the toxic substance in the electroplating of metal sanitary appliances it was decided to implement a trivalent chromium process.

Substituted substances

Alternative Substances

Reliability of information

Evidence of implementation: there is evidence that the solution was implemented and in use at time of publication

Reason substitution

CMR
skin/respiratory sensitizing
other toxic effects
ecotoxicity
physical hazards

Hazard Assessment

a) Human health: A substance of very high concern (Chromium trioxide) is substituted with substances of lower toxicity. A substance of very high concern (Boric acid, Repr. 1B, H360FD) remains in the process. At the time point when the case study was described boric acid has not been placed on the authorisation or restriction list but is under evalutation. It is assumed that the overall risks for human health are reduced in comparison to the conventional procedure.

b) Environment: e.g. waste reduced/increased Treatment of chromium trioxide containing wastewater by chemical reduction was necessary, because chromium trioxide is not allowed to enter water bodies. This treatment will be no longer necessary.

Description of Substitution

a) Motivation why to apply the alternative:
The authorisation applicable to the company expires in 2024. The high costs of reviewing the authorisation have provided the impetus to take the initiative. There are several alternative chromium III processes, but not with the required properties. Therefore, the chromium III process was optimised in close cooperation with a supplier.

b) Description of procedure or technology (including pre-/post-processing):
Chrome coating of metals is an electrochemical process. Parts are cleaned and degreased in several baths. Nickel sub-coating and, on top of this, chromium are electrolytically deposited. Coated parts are passivated electrochemically and finally rinsed. The overall process is fully automated.

c) Way of application: e.g. spraying, dipping, open/closed system etc.:
Parts are manually attached to racks. Racks are moved by a suspension crane into the galvanising plant where they are automatically transported along the bath line and dipped sequentially into the respective baths.

d) Risk management measures (technical, organizational and personal):
Access to the galvanising plant and to the baths is restricted to maintenance purposes only for specialised staff. Exhaust systems are installed at the upper edges of the baths. During maintenance and control personal protection equipment (protective coverall) is worn.

Advantage or Disadvantage of alternative

Aspect	Advantage/disadvantage to conventional process
Technical requirements	Corrosion resistance: as defined by EN 248 met by 95% Chemical resistance: OK Wear resistance: OK Adhesion between coating and substrate: OK Hardness: OK Sunlight resistance / UV resistance: met by 90% Temperature resistance: OK Coating thickness: OK Nickel leaching: OK Geometry: no restriction Process temperature: no restriction
Implementation	Competitive disadvantage as long as Cr(VI) process are still authorised! Expenses for new plant technology
Operational expenses	Labour costs: + 4% (bath maintenance) Throughput: + 14% Process quality: identical Process costs: + 23% (chemicals) Material costs: + 19% (analytical instruments) Energy costs: + 4%

Further supporting information:
Costs for ESH, OSH and waste disposal are potentially lower, but as the protection level will be upheld there is no change.

General economic aspects:
Service life of products is comparable to products coated with chromium trioxide. Availability of materials is comparable to the Cr(VI)-based process. The presumed costs of up to 250,000€ for a temporary authorisation are very high and a guarantee for an authorisation allowing the further use of chromium trioxide is not certain. Therefore, the user has decided to put this investment into a functioning replacement process.

 

Case/substitution evaluation

The case story shows the replacement of chromium trioxide in decorative chrome plating with a functional character by using trivalent chromium. A clear added value for occupational safety is the elimination of the carcinogenic hexavalent chromium. If available, occupational exposure limits for the alternative substances used must be complied with.

State of implementation

In use

Availability of Alternative

The chrome III plating process has been implemented and is used for customer orders. Approvals have been obtained from customers for the coating. The required criteria of factory standards are fulfilled. The surface is approved for mixed installation with workpieces that were chromium-plated using the chromium trioxide process.

Type of information supplier

Producer / distributor

Further information

The factsheet describing the case study is available as a pdf download: to factsheet 439-EN

Publication source: author, company, institute, year

company

Date, reviewed

June 25, 2023