Selected Answers

From Alan Denney of AKD Materials Consulting Ltd on December 7, 2017:
I have not come across the term "mechanically galv ...read more I have not come across the term "mechanically galvanized." What is this? To me there are "galvanized,"  i.e., hot dip galvanized, electroplated coatings and paint coatings.

From Mike Beitzel of Modjeski and Masters on August 29, 2016:
I am not sure there exists a conflict when ASTM A3 ...read more I am not sure there exists a conflict when ASTM A325 bolts are to be used. To my knowledge there is no structural reason for preference for mechanically galvanized high strength bolts over hot dip galvanized provided proper tightening protocals are followed. There is a restriction on the use of hot dip galvanized bolts on ASTM A490 bolts due to concerns with hydrogen embrittlement as a result of the galvanizing process and these bolts can only be mechanically galvanized or treated with other zinc coatings. A good practice would be to paint mechanically galvanized bolts. This should include a zinc prime coat and all other coats of the structure paint system to enhance fastener coating life as well as for aesthetic considerations. The zinc primer is needed to address the loss of galvanizing that results from bolt tightening impacts.