BS EN 4707:2020 pdf free.Aerospace series – Acid pickling of aluminium and aluminium alloys without hexavalent chromium.
BS EN 4707 This document specifies the acid pickling of aluminium and aluminium alloys free from hexavalent chromium.2 Normative references
There are no normative references in this document.3 Terms and definitions No terms and definitions are listed in this document. ISO and IEC maintain terminological databases for use in standardization at the following addresses:●ISO Online browsing platform: available at http://www.iso.org/0bp
●IEC Electropedia: available at http:/ /www.electropedia.org/4 Purpose of process 4.1 Pre-treatment before penetrant testing/ penetrant inspection.
4.2 Pre-treatment before anodizing.4.3 Final treatment for parts prior to adhesive bonding application.4.4 Final treatment before welding or brazing.
4.5 Pre-treatment before chemical milling.4.6 Final treatment for parts prior to painting application. 4.7 Pre-treatment for parts prior to surface conversion coatings.4.8 Desmutting, after alkaline etching or acid pickling.5 Information for the processor ●designation, see 9.5;● number of the material standard and metallurgical condition of the latter; ● sequence of operations; ● areas to be processed; ● treatment. 6 Condition of parts prior to processing Fabrication of the parts shall have been completed before pickling.Toolings, fixturings, and metal tooling masking must be protected from the corrosion and/or free from
corrosion or another deterioration detrimental to the treatment during their use.Design of the toolings and racking must be achieved in order to:●avoid any retention of air or solution on the parts;●allow the neutralisation and the suppression of the solutions during rinsing operations;● avoid any accidental contact during treatment between parts and tank equipment, and between various parts.Materials used must be resistant to temperature and chemically compatible with the products involved in the sequence of operations.A second alkaline degreasing shall be performed after pre-degreasing, if necessary.The alkaline degreasing shall be: ●corrosion inhibited; ●preferably silicate free and borate free type (especially for dye penetrant inspection). Generally alkaline solutions with pH between 9 (nine) and 11 are considered as degreasing-etching solutions, whereas those with pH between 7 (seven) and 9 (nine), are considered only as degreasing solutions.For the parts to be bonded, a silicated free alkaline solution is mandatory.After alkaline degreasing/cleaning, the parts shall be thoroughly water rinsed and inspected for water break. Cleaning shall be repeated if break occurs.BS EN 4707 pdf download.