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Adopted opinions and previous consultations on applications for authorisation

Adopted opinions and previous consultations on applications for authorisation


This page provides further information on the applications for authorisation or review reports, which have undergone consultation. The applications for authorisation are in the opinion development phase until the final opinions of the Committees for Risk Assessment and Socio-economic Analysis have been adopted and sent to the European Commission. The European Commission's decision-making process can be followed through the comitology register, where further information is published about the REACH Committee's past and upcoming meetings.

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Substance Details

Chromium trioxide
EC Number
CAS Number
Entry Nr in Annex XIV
Use name
Functional chrome plating of piston rings for two-stroke and four-stroke large bore engines as applied in the industrial sectors Construction & Industry, Power Generation, Railway and Maritime.
Broad information on use applied for (conditions of use and function)
Chromium trioxide is applied in functional chrome plating for the surface treatment of piston rings, varying in shape and dedicated to the use in pistons of 2- and 4-stroke large bore engines (LBE). LBE are used in the industrial sectors Construction & Industry, Power Generation, Railway and Maritime. In general, piston rings fulfil the functions of sealing the combustion chamber and retaining oil outside of the combustion chamber.
The process of functional chrome plating is conducted by immersing piston rings (ferrous materials ranging from different sorts of low-alloyed cast iron to high-alloyed chromium stainless steels, nitrided base materials) in water based chromium trioxide containing baths to electrochemically deposit a metallic chrome layer.
In case of piston rings, also the pre-treatment, comprising etching/pickling and cleaning, includes the use of chromium trioxide. This pre-treatment can be applied for all kinds of piston ring base materials and prepares the material for the subsequent coating by removing undesired residues from the surface. The etch rate is well-defined and adjustable, so constant quality of the pre-treatment process can be assured. Additionally, the pre-treatment chemistry is fully compatible with the main process.
The result of the functional chrome plating process is a specific metallic chrome coating (free from hexavalent chromium) predominantly reinforced with ceramic or diamond particles which increase performance significantly and set the industry benchmark for piston ring applications. This metallic chrome coating provides the article with the following essential functionalities:
- excellent tribological properties such as high mechanical and wear resistance (10-20 μm/1000 h (two-stroke); 1-10 μm/1000 h (fourstroke)), and a low coefficient of friction (0.05 – 1 (two-stroke); 0.04 – 0.8 (four-stroke)), so functioning of piston rings, cylinder liners and piston grooves is maintained over the required vehicle life time;
- good machinability (in order to achieve the requested functional shape and surface);
- the possibility to produce various designs (e.g. full face coatings, semi inlaid coatings or sharp edge design); and
- the possibility to produce side face coatings.
- layer thickness > 100 μm of the final metallic chromium surface deposits of piston rings for LBE.
The entire process is specified for LBE applications where this combination of performance characteristics is critical. All requirements apply to piston rings for engines in current production as well as for spare parts Annual tonnage used: 120 tonnes per year on 1 site. Requested review period: 12 years.
Use applied for number in application for authorisation
Broad information on use applied for (Use descriptor system)
Sector of end use (SU): 0
Environmental release category (ERC): 6b
Process category (PROC): 2, 8b, 13
Product category (PC): 14
Article category related to subsequent service life (AC): Not relevant
Technical Function: Provision of tribological properties and durability
Summary table of RMMs and OCs (non confidential)
Section 9 and 10 of the CSR (original and updated, if available) (non confidential)
Analysis of Alternatives (non confidential report)
Substitution Plan (non confidential summary)
Socio-Economic Analysis (non confidential report)
Joint Analysis of Alternatives and Socio-Economic Analysis (non confidential report)
Explanatory note
Additional information
Federal-Mogul Friedberg GmbH
Application type
Commission decided
Other consultations on the same/ similar use
Comments submitted to date
Download [ZIP]
Response to comments by applicant
Responses to RAC and SEAC requests by Applicant(s) (non confidential)
Compiled RAC and SEAC opinions
Minority positions
Adopted commission decision (OJ summary)
Authorisation decision

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