Number

438-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 applying 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 and to eliminate chromium trioxide completely. In parallel, the nickel sublayer will be substituted by a copper-Bakar layer.

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:
Two substances of very high concern (Chromium trioxide and Nickel sulphate) are substituted with substances of lower toxicity.
A third substance of very high concern (Boric acid, Repr. 1B, H360FD) remains in the process, which is under regulatory evalution but has not been placed on the authorisation or restriction list at the time point when the case study was described. It is assumed that the overall risks for human health are reduced in comparison to the conventional procedure by avoiding the use of chromium trioxide and nickel sulphate.

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. In particular, it is not possible to do without nickel in all of these processes. Therefore, the chromium III process was optimised in close cooperation with a supplier. Leaching of nickel from finished products is completely eliminated as nickel is replaced. This is an important aspect as nickel leaching from sanitary fittings is considered a serious problem. The same applies to consumer products that come into direct contact with the human body, such as children's toys, car keys or indirectly via shop fittings for food, bread baskets and the like.

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. Special Copper -Bakar is deposited as substitute for the Nickel sub-coating. Chromium is electrolytically deposited on the sub-coat. 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 (no Nickel in product) Geometry: no restriction Process temperature: no restriction
Implementation	Competitive disadvantage as long as Cr(VI) process are still authorised! The coating process is patent pending. Expenses for new plant technology
Operational expenses	Labour costs: + 4% (bath maintenance) Throughput: + 12% Process quality: identical Process costs: + 18% (chemicals) Material costs: + 15% (analytical instruments) Energy costs: + 3%
Other	The DVGW (German Association of the Gas and Water Industry) certificate of conformity has been available since 03/2022. The galvanized products comply with the limit value requirements from the Drinking Water Directive (TrinkwV 2001).

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)/Ni based process. The main advantage results from the combined transition from Cr(VI)/Ni to Cr(III)/Cu-Bakar and thus the removal of nickel from the plating process. The bath temperature is lower for Cu-Bakar plating (25-30°C instead of 60°C) than for nickel plating, and the current is lower (~3 A/dm2 instead of ~4-6 A/dm2). The process speed improves considerably as the undercoat Cu-Bakar and the topcoat Cr(III) can be applied wet in wet.
The manual activity of plugging the parts, which is necessary in the Cr(VI)/Ni-based process to prevent nickel contamination into the drinking water, is eliminated. As nickel is no longer applied in the coating process, the time-consuming and expensive product testing for nickel leaching can be omitted. 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.
The DVGW certificate of conformity has been available since 03/2022. The galvanized products comply with the limit value requirements of the German Drinking Water Ordinance (TrinkwV 2001).

 

Case/substitution evaluation

The case story shows the replacement of chromium trioxide in decorative chrome plating with a functional character by using trivalent chromium. In addition, the nickel layer is replaced by copper.

Boric acid (Repr. 1B, H360FD) remains as SVHC in the presented alternative process. It is also used in the conventional plating process. The risks for man and environment are still under regulatory evaluation and remain unclear at the time of compiling the case story. Should information and evidence regarding this alternative or a safer and more sustainable alternative be present, please contact SUBSPORTplus.

In Germany, there are limit values for various metals, such as chromium, nickel and copper, according to the Drinking Water Ordinance. The limit values (e.g. for copper of 2 mg/l) can be complied with by the alternative. An added value of the alternative is the elimination of the nickel sublayer to increase drinking water safety. If available, occupational exposure limits for the alternative substances used must be complied with.

Release of nickel compounds into the drinking water is known to occur from conventional plated products (see further information), if the products are not plugged before coating. However, plugging is time and cost intensive (personal communication). Substitution of the nickel sublayer is an alternative to increase drinking water safety and avoids the use of nickel sulphate in the first place.

For occupational safety and health: Substitution of two carcinogenic substances at the workplace is regarded as added value. If available, occupational exposure limits for the alternative substances used must be complied with as well. Adequate protection measures need to be taken into account at the workplace after a proper risk assessment.

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. The nickel leaching test according to DIN EN 16058 (26 week test) was passed.

Type of information supplier

Producer / distributor

Further information

The factsheet describing the case study is available as a pdf download: to factsheet 438-EN

Publication source: author, company, institute, year

company

Date, reviewed

June 25, 2023