Summary for galvanizing adhesion test Discussion
Adhesion of galvanizing is discussed as a minor concern in hot dip galvanized coatings, because the coating is formed by alloying with the steel rather than simply sticking on. In response to the question about standard tests under ASTM A123, Geoff Crowley says adhesion is rarely an issue and that if a standard mentions it, it should also specify how to measure it or point to another standard. Ameen Syed Roohul adds that some inspectors still insist on checking adhesion and says ASTM A123 calls for using a stout knife with considerable pressure; if the coating remains intact, adhesion is considered good enough. Years later, Vishwesh Nair asks whether a hammer test is required or only used when there is suspicion about coating stability. The thread then identifies the method as the "Pivoted Hammer Test," though the excerpt cuts off before giving full details.
Q. What are the standard recommended tests for hot dip galvanized material as per ASTM A123?
MOHIDEEN ABDUL KHADER
QC INSPECTOR – KUWAIT
February 29, 2008
March 4, 2008
A. Adhesion is rarely an issue with hot dip galvanizing, but if you find a standard referring to it, it should also tell you how it can be measured or refer to another standard that does.
Because the mechanism of coating is alloying, not just a coating sticking to the steel, it either has happened or not. Rarely does the alloy form but be not adhered.
Geoff Crowley
Crithwood Ltd.
Westfield, Scotland, UK
A. Adhesion as Mr.Geoff said should not be a major problem, but still some inspectors insist on that, according to ASTM A123, take a stout knife and with considerable pressure take forward movement if the coating is intact your adhesion shall be good enough.
Ameen Syed Roohul
– Sharjah, U.A.E.
March 19, 2008
Q. Is it really required to conduct the hammer test? Or only when the inspector has a suspicion w.r.t. the coating stability?
As per ASTM A123, just with the help of a knife can we conduct the test or is any other apparatus required?
Vishwesh Nair
airport project – Abu Dhabi, UAE
July 25, 2016
A. The Test is called: “Pivoted Hammer Test”. The hammer is made per IS 2629. You can take its equivalent.
You are advised to do the test as per specification only. In case hammer is wrong there is possibility of product GI failure.
Umesh Dalela
Galvanizers & Consultant – Delhi, India
August 5, 2016
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