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Up Topic Welding Industry / Inspection & Qualification / Elevated water tank material
- - By jwright650 (*****) Date 12-06-2018 13:53
I need to test some studs that will be stud welded onto the wall of an existing elevated water tank. The town, and the tank maintenance vendor do not know what grade of material the tank wall was made of. Do you guys think that it would have been made out of anything other than ASTM A36 or ASTM A572 gr50 plate?  The town thinks, given the date that the tank was built, that mild steel A36 or A527 gr50 plate is a good assumption.

I had proposed using a sample piece of plate to test shooting these 1/4"x20 studs on the ground in the same position before attempting stud welding to the tank at 125' while hanging over the handrail.
Parent - - By TimGary (****) Date 12-06-2018 14:54
Hi Ya John.
Sounds like you're having fun doing guess work.

I'm not really sure from the info you stated whether you're trying to qualify the installation procedure then inspect the end result, or if you're just doing a post weld inspection, so I'm going to assume the former...

Assume is a big word, but your base metal guesses sound like a safe assumption, as long as the studs to be installed are not holding up a walkway or platform that people will be walking on, or some other such critical situation.... but you know that drill.
Don't forget to CYA by getting a competent person to accept the procedure, regardless.

If you qualify a procedure to B2.1 on any M#1 steel, you'll be covered for a larger group of steels than just the 2 you mentioned, which will also broaden the acceptable material range for the studs to be used.

As for final inspection, I would reject any weld that was not welded to clean, shiny base metal, does not have a clear flash 360 deg around the stud base, and can not survive a 15 deg bend and straighten test.

Parent - By jwright650 (*****) Date 12-06-2018 15:04 Edited 12-06-2018 15:06
The town contacted me when they wanted to add some antennas to their water tank. They want me to inspect the work of the contractor. They originally gave me drawings of the brackets being welded to plates that would be field welded to the tank wall near the top of the tank. All of this work was proposed to be performed at the top of the water tank. The contractor contacted me and says that they normally shoot 1/4"x20 studs to the tank and then build the brackets on the ground and bolt them in position on the tank. Personally I like the contractor's proposal, which eliminates a lot of elevated work other than shooting some studs and bolting the brackets on. I was trying to work up a scheme to test the stud gun/operator on a sample plate first, then after all of the kinks are worked out and sound studs are being produced, have them apply the studs to the tank.

edit: I like your idea of using B2.1
Parent - By jwright650 (*****) Date 12-06-2018 18:41
Thanks Tim,
It appears that we can shoot 10 samples (5 bends, and 5 torque tests) and qualify the stud welding procedure on the M-1 material.
I just want to verify that these guys can in fact shoot these studs successfully before ascending that 126 foot ladder. :eek:
Parent - - By thirdeye (***) Date 12-06-2018 19:11

Mild steel is a good assumption because of cost and it's quite malleable and is easily rolled, and it's easier to fit-up during erection. Have you looked for a manufacturers name plate?  They are usually in the 5" X 5" size and found in a conspicuous location, like on a removable access plate or at the bottom of stairs or ladder.  With the information from the nameplate you should be able to find out the type of material used.
Parent - - By jwright650 (*****) Date 12-06-2018 19:29
Thank you for that bit of info! :cool:
I will certainly look for that plate when I gain access to the tank. I have seen it from's the tallest structure in that small town and you can see it from miles around.
I have been sending emails all morning discussing all of this testing with the contractor and the representative from the town. I highlighted all of the pertinent info in the code and sent it out all of the parties involved looking for a blessing from everyone before this work starts (Monday, December 10th). Nothing like scrambling at the last minute to get my ducks in a row.
Parent - - By 803056 (*****) Date 12-07-2018 04:21
Where is the Engineer that represents the tank owner?

Are they adding the antenna without anyone reviewing the design or giving consideration to the materials involved?

Just asking.

Parent - - By jwright650 (*****) Date 12-07-2018 11:49
There is an engineer's stamp and signature on the set of contract drawings. The contract drawings first showed all of this work being welded in place at the top of the tank, the last set that I saw has the connections revised and showed 4 studs at each connection so that these antenna brackets are put together on the ground and bolted in place on the tank.
Parent - - By TimGary (****) Date 12-07-2018 12:53
Sounds like a good way to test the cyclic load carrying capability of those stud welds...
I would think a re-inspection after about a month would be in order, as insurance against potential falling objects?

Be careful up there John, we need you to stick around :)

Parent - - By 803056 (*****) Date 12-07-2018 20:29 Edited 12-07-2018 20:32
1/4-20 threaded stud: that means the diameter at the root is on the order of maybe 3/16-inch? How long before corrosion reduces that to 50% or less? I take it the antenna are pretty light.

Parent - - By jwright650 (*****) Date 12-07-2018 21:41
Yup, these attach above and below the catwalk and also to the rail of the catwalk. Looks like a single piece of 2.5" schedule 40 with a U-bolt attaching it to the rail of the catwalk and L3x3 kickers that attached to the 3/8" plate that will be bolted to the studs(4/plate). Drawing says the antenna is 101.4 lbs. There are a total of 3 antennas with this same type of mounting that will be added.
Parent - - By 803056 (*****) Date 12-07-2018 22:38
And what do they weigh with 1-inch of ice?

So, exactly how many 1/4-20 bolts actually secure each antenna? I'm assuming they are just carbon steel threaded studs?

Parent - - By jwright650 (*****) Date 12-08-2018 12:28
I suppose that question about the accumulating ice load is for the engineer who specified these. In my 53 years, I haven't seen an inch of ice here, we have had storms where we had as much as a 1/4" of ice though.

There are 8 studs(4/plate) to the tank wall above and below the rail, plus a u-bolt on the rail, yes carbon steel with a coating of epoxy applied after installation.

Is there something bothering you about this antenna inspection that you haven't come out and said directly? Just curious as I'm feeling some weird vibes through your posts.
Parent - - By 803056 (*****) Date 12-08-2018 13:14
It sounds like the u-bolt carries most of the load and the studs stabilize the antenna so they don't vibrate in the wind.

I am always a little bit suspect of small diameter carbon steel fasteners that are used in exposed conditions. Corrosion happens and it doesn't take much time before the strength is affected. They're fine for the first few years, but after that, who knows.

Some of the antennas I've seen are much heavier than 100 pounds. Granted 100 pounds isn't all that heavy.

I had a court case a couple of years ago that involved a personal injury where some 1/4-20 fasteners failed and the fella involved broke his neck and shoulder. The manufacturer made the claim the bolts wore tightened to 120 ft-lb of torque using a 4 ft long pipe on a wrench. I told the lawyer there was no way that could be true. Long story short, it is easy to over tighten the 1/4-inch diameter fastener. I think the bolts actually twisted off at roughly 19 ft-lbs of torque. The case was settled without going to trial.

So, no. I don't have any issues other than controlling the tightness and corrosion, but as I mentioned, it sounds like the u-bolt takes most of the load. So, what is the diameter of the u-bolt?

Best regards - Al
Parent - - By jwright650 (*****) Date 12-08-2018 13:48
1/2" u-bolt
I understand the effects of corrosion.  I was recently contracted to measure what was left of some columns in a 10 story building.  The web of one column had a 3" x 5" hole rusted through and the flanges only had 1/4" left.
Parent - - By 803056 (*****) Date 12-08-2018 14:10
I've seen worse on bridges! Corrosion is something we live with. Hopefully the engineer involved gives it due consideration.

In this case, I've convinced myself that the u-bolt is the primary load carrying element.

Merry Christmas!

Parent - - By jwright650 (*****) Date 12-09-2018 00:52
Merry Christmas  Al.
Parent - By jwright650 (*****) Date 12-12-2018 22:44

Welded (10) studs in the Side Hand position (2S) and it went really well. Bent (5) studs over past 15° from the original position without any incident. Torque testing went good, torqued the remaining (5) studs to 4 ft-lbs without incident. Increased the torque in 2 ft-lbs increments and had failures at 10 ft-lbs (at approximately 1/4" above the welds), one survived to 12 ft-lbs but pulled the threads out of the nut. Contractor is going to torque the locking nuts at 4 ft-lbs when he gets the brackets in position on the tank.
Parent - - By jwright650 (*****) Date 12-19-2018 21:43
A seal blew out in the lift today and we had to come back down. Not sure how much fluid was left in the tank by the time it was down and engine cut off. The level was below the sight glass. Rental company came pretty quick, replaced the seal and added alot of hydraulic fluid to get it back up in the window of the sight glass. Went back up without any further drama and finished looking at everything.
Parent - - By 803056 (*****) Date 12-19-2018 22:19
You usually have to go to an amusement park for a ride like that!

Did you notice what might have felt like a small hairy ball in you throat as you decended?

I was working on the first Hartford Civic Center in the mid 1970s. As was the way it was done in those days, a hydraulic crane would lift us up to the roof in a scale bucket. later the operator would let us down at lunch. Repeat the same after lunch. Each time the operator would power down, because the was no "free fall". This went on for a couple of weeks. Then one day at lunch the scale bucket with the entire crew was free falling toward the ground. We all knew we were going to die! Then about 50 feet off the ground the bucket slowed and came to a stop about 6-inches off the ground. The operator was laughing so hard he nearly fell out of the crane cab.

"You should have seen the look on your faces!"

George was always a hoot to work with. Once, on a bridge job, he lowered the bucket with the entire crew into the river up to our chest! It was a good thing it was a hot summer day. No one really cared!

Oh yea, that little hairy ball was your left nut. I hope you swallowed it!

Merry Christmas!

Parent - By jwright650 (*****) Date 12-19-2018 23:20
I prefer the man basket on the crane hook.

LOL, Al.
Up Topic Welding Industry / Inspection & Qualification / Elevated water tank material

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