Applications for authorisation AFA057-01 – Multiple Cr(VI)

Overview

Public consultation on alternatives

Reference: AFA057-01

Applicant: Robert Stuart Limited

Application type: Initial

Substance names:

Chromium trioxide (CT) (includes “Acids generated from chromium trioxide and their oligomers”, when used in aqueous solutions)

• EC Number: 215-607-8
• CAS Number: 1333-82-0

Sodium dichromate (SD)

• EC Number: 234-190-3
• CAS Number: 10588-01-9

Potassium dichromate (PD)

• EC Number: 231-906-6
• CAS Number: 7778-50-9

Proposed use:

The use of hexavalent chromium (Cr(VI)) substances for the surface treatments of engineering components for the aerospace and defence industry to ensure that the performance requirements set by the Design authority are followed and achieved. The processes comprise conversion coating (SD), hard chrome plating (CT/PD), anodising (CT) and post anodise sealing (SD).

Broad information on use applied for (conditions of use and function):

This use covers the coating of metal components using CT, SD or PD in the aerospace and defence industry and its supply chains where any of the following key functions are required: corrosion resistance (and active corrosion inhibition), chemical resistance, adhesion to subsequent layer, layer thickness, temperature resistance, electrical resistivity, and pre-treatment compatibility. When a component needs to meet one or more of the above qualities that is not achieved by the base material, the engineering drawing will state the process required and the specification to work in line with.

These specifications could include:

• Type of surface finish
• Thickness of the surface finish
• Set chemistry parameters.
• Testing parameters

In these processes, a Cr(VI) containing solution is applied to the metallic component to form a coating such as passivation, anodic film or an additional protective layer on the surface. The level of protection is proportional to type and thickness of the surface treatment.

List of descriptors:

• Sector of end use (SU): 0: Other: Aerospace and defence industry and its supply chains
• Environmental release category (ERC): 5
• Process category (PROC): 0, 1, 5, 8b, 9, 13, 21, 28
• Product category (PC): 14
• Article category related to subsequent service life (AC): N/A
• Technical Function: Other: Corrosion resistance (and active corrosion inhibition), chemical resistance, adhesion to subsequent layer, layer thickness, temperature resistance, electrical resistivity, and pre-treatment compatibility

Annual tonnage used:

• 0.5 tonnes per year for chromium trioxide
• 0.25 tonnes per year for sodium dichromate
• 0.05 tonnes per year for potassium dichromate

Review period requested: 12 years

How to submit comments

Provide some basic information on possible alternative(s) in the online survey below but more detailed information should be provided in document(s) prepared using the commenting templates in the related section below. A “public version” should always be completed and will be published after the consultation has closed. If you want to include confidential information in your submission, please additionally complete a “confidential version” and submit both versions as attachments.

The consultation lasts for 8 weeks (unless otherwise specified) and closes at 23:59 London time (BST).