It is imperative to adequately vent all hollow steel sections prior to galvanizing. As you can see from the photos below, failing to do this can not only be dangerous, but it also reduce the quality of the finished product.
Photo 1 shows ‘steam burn’ . As the vent holes are small air is trapped , super heated then burns the preflux off creating ‘miss’.
Photo 2 shows same as above from another angle
Photo 3 this end immersed 1st shows no issue
Closed section steel requires 25% end section ventilation.
[nggallery id=5]