By aevald 
Date 10-08-2014 02:32
Edited 10-08-2014 02:36
Hello rokkboxxer, from what I see in those photos I don't believe that those cracks are related to the welds, they look more like cracks in the galvanizing in that area. In other words, it looks as if the galvanizing pooled there and as it cooled it resulted in the cracks that are seen in the photo. Often times you could see issues with the continuity of the galvanized layer due to poor cleaning prior to dipping. If it was welded with a flux-cored process and the slag was lackadaisically removed you might see some of those issues or if dirt was left in spots the galvanizing might cover it over and then fail down the road by flaking off or other such issues. Best regards, Allan
Hello Rokkboxxer,
WELCOME TO THE AWS WELDING FORUM!!
Overall I agree with Allan. Overall. BUT, I believe it prudent to acknowledge that any issue with coating is applicable to the welding and all other work associated with the welding. In this case, poor clean up.
When looking at a member that will be subjected to galvanizing or other coatings one must know exactly what is expected for material preparation. In most cases at least cleaning to SP-2 which is just a particular codes way of saying clean by hand to the degree that a dull scraper run across rust and other contaminants has removed most of the loose particles (not the exact wording but close enough to describe what it appears is going on in your pics). I'm not going to get too exact and precise because of your level of current information, education, and experience as I perceive it from your post.
Now, in some applications the coating you have pictured would not be satisfactory/acceptable. But, WE do not know the exact function, usage, application, environment, of this piece of equipment.
But, at a first glance with information provided I would say the comments made by your consultant was quite probably correct.
To further explain for you what is going on appears, as Allan stated, to be related to the preparation being inadequate to provide any higher of a quality finish. Slag and/or dirt/contaminants of some kind left on the surface, weld discontinuities that are possibly acceptable for the usage but should have been ground smooth in order to facilitate better coating finish (porosity, overlap, etc) and other factors.
Not knowing how this is used is a problem but suffice it to say that galvanizing is not a magic cure all, protect all without proper material design, welding, and clean up. We also do not know who was responsible for the clean up. Sometimes that is hired out, other times the fabricator will be responsible to finish the work to a certain level of cleanliness and 'perfection' in order to improve the adherence of coatings and the life span of the product, and it can be left to the galvanizing facility if they have the equipment to do preparation of parts.
Irregularities in the surface, even if acceptable to a welding code, will cause problems for coatings. Add to that the possibility, again as Allan stated, that the zinc pooled up in those areas and during cooling left that type of surface appearance.
I hope we have helped you to see that it may be acceptable, is probably not weld or structurally related especially to the extent that it is dangerous, and see the large variety of applications and methods of any process of finishing the work.
Good observation and question for a first post. Keep them coming.
He Is In Control, Have a Great Day, Brent
I had a similar issue a few years ago. A PM took me to a jobsite where he said that some of our welds were blobbed up and had cracked. They look terrible, he said. So he took me to see them. Turns out, it was where the galvanized coating had "blobbed up" and cracked. I tried to tell him that it was just "blobs" of galvanizing. Then he asked me to climb the ladder and knock off the blobs with a chisel. Before I climbed the ladder, I told him that they probably couldn't be removed. So he snatched the chisel out of my hand and went up the ladder to remove them. Striking them several times with the chisel did absolutely nothing, which I thought would be the result. Then, and knowing that a hammer wouldn't be of much help, I handed it to him and said "You might need this." After a couple minutes of him striking the chisel with the hammer, in an attempt to dislodge the "blobs", he finally gave up. He was hammering so hard, at one point he almost fell off the ladder. The look on his face was priceless when he realized that he couldn't remove it.
Something ain't right. HDG is soft. If the blobs are in fact "drips" or blobs of zinc, they should cut fairly easily with a chisel and hammer.
Al
It definitely wasn't weld, and they were as hard as a rock. I would never let anything out of the shop that looked like that. I've seen these blobs before. They appear more in corners than anything else, and sometimes, even when the corners are sufficiently clipped. That was also the case here. I know that galvanizers request holes and clipped corners to be certain sizes, which we always do, but if the pieces are dipped incorrectly, for maximum drainage, this can happen. I've also seen trash on a galvanized surface where the galvanizer hasn't done a very good job cleaning the vat.
We galvanize most of our finished product and see this quite often, along with all sorts of other undesirable "defects" in the galvanizing. To make matters worse, the ASTM A123 standard that most hot-dip galvanizing is performed to says that these are acceptable. What can you do?
On a humorous side note, recently we had our machine shop QC Inspector stop a loaded truck from leaving our yard because he thought there were some "unacceptable" welds on a welded steel operator enclosure we had just manufactured for one of our ski-lifts. I was asked to come out and take a look. This enclosure had steel entry doors on each end and was painted a high gloss green. The "welds" he was looking at were silicon caulk between the metal door frames and the steel shell of the enclosure. Pretty funny.
I've seen this before on handrails and platforms. Some of what I saw was from poor cleanup in joint corners and hard to reach areas. The acid bath won't clean the slag off the welds and the zinc will not stick to slag. These indications may be due to poor dipping processes where there was not adequate time for the excessive zinc to runoff or the vat was not hot enough for the zinc to run off prior to removing it from over the vat from drainage. The conditions were reported to the project engineer who said it was OK. Unfortunately after returning to the site a couple of years later it was quite pretty to see the rust stripes running from the "holidays" where the zinc did not contact and coat the carbon steel but the rain, fog, snow, and dew did contact the bare steel and rust had begun to take it's toll. Not a great problem till the structure deteriorates and fails with some one standing on it.
I think you got some good advice here and I think you are wise to bring things like this to the attention of those who can determine the degree of necessity for repair. Probably bumping your head against the wall but it's good experience.
