Hot Dip Galvanizing after PWHT

[Mec.tec]

We are manufacturing an ACHE in our shop.Material is carbon steel SA 516 Gr 70 and PWHT is required.Client want us to perform Hot dip Galvanizing of box headers external surface only.Please share your views,is there any effect on the mechanical properties of material.Do share an example of similar case if any.

 

[metengr]

Hot dip galvanize AFTER PWHT is completed.

 

[Duwe6]

PWHT after galv will make the galv drip, smoke and run off! Galv tank is about 850°F, and the zinc is molten and 'wet'. PWHT temp is 1100°F and higher.

And a further 850° after 1150° won't hurt anything, IF the header boxes are vented so the heat expansion of the air inside doesn't make them blow up. Galvanizers get pretty sensitive about dipping tightly sealed items into their tanks.