Galvaguide No.2

Hereford Galvanizers GroupWestfields Trading Estate, Hereford HR4 9NS UNITED KINGDOM

Tel: (01432) 267664 Fax: (01432) 352735email: zinc@hereford.galvanizers.co.uk http//www.galvanizers.co.uk

COPYRIGHT HEREFORD GALVANIZERS LIMITED 2005

Preparation of Steel for Galvanizing

A metallurgically clean steel surface is an absolutenecessity for satisfactory hot-dip galvanizing.Contamination on the steel, including rust andscale caused by oxidation of the steel surface,oils, light grease, etc. must be removed prior toprocessing if the galvanizing is to be successful. Toachieve this clean surface, all steelwork isimmersed in tanks of dilute Hydrochloric Acid, apart of the process called ‘pickling’.However, paint and solvent based markingscannot be removed by pickling and lead todefects in the galvanized coating, if not removed,in the form of bare areas (see photo 1).

Steelwork is often identified by use of crayons,paint or solvent-based markers (see photos 2 and3). It is vital that these markings are removed bypaint stripping or mechanical means for allgalvanized jobs, or better still, we stronglyrecommend the use of water-based markers orchalk which are ‘galvanizing friendly’.

We are sure that all our customers willappreciate the potential cost involved inmechanical removal of the quantities ofpaint/crayon as shown in our photographs andyes, these are photos of actual jobs whicharrived at our works!

In summary, for all galvanized jobs, please use amethod of identification which helps us to helpyou. Please contact us if you require anyinformation on suppliers of ‘galvanizing friendly’markers.

photo 1