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Up Topic Welding Industry / General Welding Discussion / Low Heat Welding
- - By Cumminsguy71 (*****) Date 04-08-2014 13:49
Ok, I was reviewing some prints the other day and engineer called out "low heat welding" to be used. Is this a contradiction? 10,000 degree welding process and I need to keep the heat low?

Alright, it is a cell tower, all galvanized, inside and out. Placing half pipes over the legs then welding the bottom and top of the half pipes to existing legs. Engineer stated that they wanted "low heat welding" so as not to burn the galvanizing off the inside of the existing leg. When I weld I use the correct heat for the rod selected. I'm not one of those "hot and fast" guys. When I was in school most guys that used my machine could not run the same rod in the range I liked to run.

I had to weld 20' welds, 3/16" up both sides of a half pipe on a tower. 120 feet of total weld. I alternated sides and welded up. The legs were around 2-1/2 O.D. Had the machine set where I like it, galvy cleaned off properly and could see the smoke exiting the holes at the top of the leg where the galvy was burning off on the inside. Turn the machine down any lower and it would barely run, difficult to get the weld in and with wind pushing you around very hard to control the arc length. It was also around zero degrees outside so preheat had to be maintained.

On the heavier pipe down low on this proposed project, 6", 5" and 4" I see no issue as the wall thickness is heavier. On the top end where they go to 3", 2" or jeez, even have seen 1-1/2 the wall thickness is so much thinner so how can it be expected to use "low heat" to keep from burning the galvy on the inside of the pipe, get penetration at the root of the fillet?

I know I could use a 3/32" rod but then you are pausing longer to get the 3/16" weld profile required by the engineer. Thinner wall and your still going to heat the inside of the pipe, likely damaging the galvanizing. Another downside to using a 3/32" is time. Tower owners, carriers and the subcontractors wanting me to weld are highly impatient and for me to stand up and say, "I have to use low heat and 3/32 rods to weld so as not to burn off the galvy inside" and they are going to have a cow because, it will cost more time and money. Although this would not be voiced openly but only to me in an undocumented phone conversation of course. 

Problems with this concept I have witnessed first hand. Half pipes that do not fit properly. 1/8", 1/4" gaps with the engineer specifying that I must add appropriate filler metal to the gap of the same grade of steel and double the size of the weld according to the gap, 1/8" gap, 1/4" weld and so on. So, with this being called out we have to weld more in one area to compensate but can make it to hot to burn the galvanizing off the inside.

I don't know if I have questions about this but had a little giggle when I read it and have wondered about this for the last year that I have been doing work on these towers. Does anybody do inspections on tower legs to check pipe wall thickness from corrosion on the inside? Like they do on pipelines? Is this just a ploy by the engineer and tower owners to somehow shift blame if future collapses cause a tower to fail and crush a home or business killing people? Saying "low heat" they can now transfer blame to the welder?

Guess I just wanted to put this out there for discussion as I found it interesting. I don't pick the correct amperage for the rod or situation, the rod does. When the weld is going in properly, toes tying in, weld profile is correct as well as penetration then that is where it needs to be. I can't make it lower to accommodate your low heat requirement and then have improper welds. I am correct in thinking this? Or am I just a boob? Clarify please.....

Shawn
Parent - By Lawrence (*****) Date 04-08-2014 14:24
Opinion:

The engineer is just making stuff up....... "low heat welding"

Why not just be clear... "Minimize heat input to preserve galv. on back side"

If you are making the correct size weld (not overwelding) and are within the required amperage range, you have minimized heat input  (assuming SMAW or GMAW).

The weld size determines just about everything really.....  More amps/WFS   you travel faster to get the same size weld...

If the correct size weld, applied within WPS or manufacturers current ranges is made and zinc burns off the back side and they don't want it to?   Thats the engineer's issue not the welder.   Same with paint.

"Low heat welding" is a cop-out by the engineer because he does not know how to provide the welder with the direction, and is unwilling or unable to specify the process controls... So he just blathers a nebulous demand...
Parent - By js55 (*****) Date 04-08-2014 14:31
Low heat welding?
Well, first there's brazing, then there's soldering, and then there's crazy glue and duct tape.
But actually, Lawrence's last sentence says it best.
Parent - - By yojimbo (***) Date 04-08-2014 14:33 Edited 04-08-2014 14:37
Cummins-

Did the engineer state he wanted "low heat welding" in the contract documents or verbally in a meeting?  Was the reason for this call out stated in either case?  You mention galvanic protection but I wondered if/where/when the reason was provided.  Hopefully one of the CWIs or welding engineers in this forum will post in response and direct our attention to some D1.1 prequalified WPS which will define "low heat welding" because in 3 decades pursuing this trade I have never run into it before.  Absent the existence of this hypothetical weld process you have zero liability IMO of any effect the welds had on the galvanizing.  Seems I remember you relating you had taken up employment rather than pursuing this work as an independent contractor.  If this is the case that would eliminate any liability on your part to less than zero.  Hell, you might be able to construct an assertive defense of your work and sue for defamation of charachter and trade reputation if it was suggested you contributed toward any negligence.  Was there a callout for low hydrogen 70XX electrodes in the General Structural Notes?  Did he suggest the use of epoxy or JB weld to glue those reinforcements in place?  Sounds more like typical CYA misdirection where someone was smart enough to identify the potential problem with the structural reinforcement design ie. galvanic destruction, but no one was going to step up to pay the cost of providing the solution.  If design was not specified in your scope of work and you followed either the direction of your supervisors or the drawings you were given then it's not your problem or worry.  And I am sure you already know, it is not uncommon for the title "engineer" as in "project engineer" or "field engineer" to have no relation to either training or a degree in engineering.  Engineer of Record is the person responsible ultimately for the approval of design and acceptance of construction submittals, including Welding Procedure submittals. EDIT:  I see one of the welding engineers has already waded in and provided a response that doesn't seem to contradict anything I pointed out so I might just be reiterating but not too far off base.
Parent - By Metarinka (****) Date 04-08-2014 17:48
well as a welding engineer, I can assure you I have never once specified "low heat welding" and that it doesn't carry any significance, or weight, nor does it give the welder  direction.  Generally the absolute best way to minimize heat input is to increase the process efficiency by welding as fast as the process allows.  A good rule of thumb is that doubling your travel speed reduces your heat input about 40%. However we all know there are practical quality limits to how fast a human can weld, Also you run into fundamental limits for how fast mechanized processes can weld. At best you can get your process efficiency to 49% with lasers or EB welding, SMAW and mig are not far behind.  These will correlate very strongly with backside temperature of a weld. 

Sounds like this particular detail was poorly engineered. If corrosion on the inside is a concern, you would either have to field paint or coat the part or re-engineer so that it wouldn't get heat affected. In all reality you can't magically hope that the backside of a piece of plate will stay cool while you lay down good weld on the outside.  

Sounds like a good candidate for bolting or field painting of some sort.
Parent - - By lo-hi (**) Date 04-18-2014 09:37
Maybe they saw the ad in the welding journal about the Fronius CMT weld process. If a robot can do it on a production line, how hard can it be in the field ?
Parent - By Cumminsguy71 (*****) Date 04-18-2014 13:50
Haha! You might be right! :lol:
- - By 803056 (*****) Date 04-08-2014 16:37
Low heat welding: it is a process common to many fabricators and erectors.

We see evidence of it's use on many occasions where we encounter incomplete fusion between the weld bead and the adjacent base metal. The process most often used to produce welds of this type, "low heat welding," is GMAW-S.

Were it not for this particular weld type, my income would suffer a substantial decline.

Best regards
Parent - - By Lawrence (*****) Date 04-08-2014 21:39
Farm code addendum ?
Parent - - By JTMcC (***) Date 04-08-2014 22:42
There's nothing out of the ordinary here. Look at enough drawings and the odd, unusual, undoable conditions just become another part of the landscape. From large govt agency's and the largest contractors on the planet.

Sometimes you can clarify with the EOR and all is ok. A lot of EOR's welcome trade related real world input. That helps everybody.
Sometimes you just have to pass.
When I pass I send a note that the current specs are unattainable and any quote to those specs cannot be finished within those specs.

It makes ME feel better that way : )

J
Parent - - By Cumminsguy71 (*****) Date 04-09-2014 01:22 Edited 04-09-2014 01:27
Process I use, SMAW, Spec on prints 70XX(7018 in this case), settings on machine around 120-130 due to the distance I have to travel when near the top but down low keep it around 115-120 is my happy zone with what I normally weld on with the towers.

This was on the prints in "Welding Notes",

"3.6 The "Low Heat" welding process shall be set up so that any field welding activity on the pole structure does not scorch or otherwise damage the existing galvanized surface on the inside of the pole shaft in and around the region of the weld."

I welded some brackets today for a gate, 1/2" thick piece 2 inches wide and 5 inches long. Welded a 3/8" thick triangle gusset to the 1/2" piece. Used proper heat and when I was done welding around the 2" long triangle gusset I saw that the galvanized was affected on the other side, discolored.

I cannot see anyway to not affect the galvanized coating on the inside of a 3" or smaller schedule 40 pipe with the wall thicknesses that they have. As some have said, JB weld, bubble gum.

Yes, tried the employee thing for a few months then found out they were nuttier than squirrel poop at a peanut factory. So, back out on my own, scratching a living but have found another tower company that contacted me about giving them some bids, so, back in the saddle again so they say.

I'm just glad that I am not a complete idiot when I questioned with that look on my face, "what?????".

Thanks for the responses, like the last sentence in Lawrence's post, LMAO!!
Parent - - By mechan (**) Date 04-09-2014 04:16
Maybe a silly question, but why not submit an RFI?
Parent - - By Cumminsguy71 (*****) Date 04-09-2014 11:15
Going to wait to see if I get the job before I concern myself with it to much but wanted to be sure I wasn't a complete moron when I read it and laughed, looks like I'll be getting it though from the looks of it.
Parent - - By mechan (**) Date 04-10-2014 06:16 Edited 04-10-2014 06:27
If you do not submit an RFI prior to being awarded the bid then you are bound by the contract documents and the "low heat welding" call out. It is much more common to submit an RFI for questions PRIOR to bidding if one has questions than waiting to be awarded the bid. Your deal, but if it is a hard money job and the engineer wanted to be a prick he could more or less say "deal with it you agreed to the required methods by submitting a bid without an RFI for clarification and please fix any burned off galvanized due to not using low heat input welding methods."

It is more or less SOP to submit RFI's prior to the bid to clarify issues like this to mitigate issues after the bid is awarded. If you are awarded the bid, they won't budge on the call out, and you decide to walk then you could face legal ramifications for doing so. It is no different than a contractor bidding the job undermanned then later on saying "I knew it would probably take five men, but I bid three men because I wanted the job so I didn't say anything". I'd tell the contractor to pound sand and send his change order to the circular filling cabinet. Who knows what process the engineer has in mind for the weldment.
Parent - By Cumminsguy71 (*****) Date 04-10-2014 14:26
Good point. :cool:
Parent - - By ssbn727 (*****) Date 04-09-2014 08:21
In a perfect world Metrinka's suggestions make sense, but we're talking about real world field welding conditions that are totally different than applying the same sort of thinking one would use in shop work which includes for the most part consistent and optimal joint openings, etc... Why is this different working on a tower? Because of the inconsistencies that will be found in the field as well as what the components and assemblies have been exposed to the degree whereby changes in wind velocities and exposure over time with the changing environment will be some of the main causes that result in the joints having various sized gaps, not to mention that the welding is performed out of position as opposed to what goes on in the shop for the most part where the overall conditions are soooooo much better to fabricate, weld and repair...

The bottom line is that when you're in the field, you must consider much more of the environment you're working which in itself will slow down production when compared to what can be produced in a relatively stable environment such as in the shop so you cannot plan the work as you would in the shop...

If I were in your shoes and was thinking of pursuing this job, I would first go over all of the area's of the tower on the print with the contractor and the EOR to educate them as to why they cannot expect you to perform the work in the same manner and with the same speed as one would witness or perform in shop conditions... And simultaneously go over the different locations where you already scouted, and know that location A will take approximately this amount of time to complete with the justification as to why, and to leave yourself a little wiggle room for anything unexpected as a cushion... And then continue to go over the same with locations B, C, D, etc. until everybody is on the same page before you even start the job...

If they object to what you propose, then walk away because if they will not listen and take into consideration what you are describing to them based on your own experience then they're not giving you the respect you deserve and should expect as a professional for going into a hostile environment and putting yourself at risk in order to get the job done especially if they don't give any consideration to the serious safety issues involved and the time it takes to implement the necessary mitigating procedures that must be followed in order to finish the job in one piece... Never forget that if they want to compromise your safety so that they could look good with the production schedule while you put yourself in jeopardy then it's just not worth it Shawn!

Respectfully,
Henry
Parent - - By Tyrone (***) Date 04-09-2014 10:50
I don't even think that in a controlled environment (shop), you could prevent damage.  I think a different weld process would need to be tried and tested.  The EOR needs to understand the ramifications of low heat input has on producing sound welds and cost/schedule.
Tyrone
Parent - - By Cumminsguy71 (*****) Date 04-09-2014 11:23
"We see evidence of it's use on many occasions where we encounter incomplete fusion between the weld bead and the adjacent base metal. The process most often used to produce welds of this type, "low heat welding," is GMAW-S."

I believe this says it best about the proposed "low heat welding". Metal thickness, rod size kind of dictate. Sure we have a range we can run but low end in my experience is miserable pace and when a snail passes you while burning the rod you, well, you get the idea.
Parent - - By yojimbo (***) Date 04-09-2014 15:03
Cummins-
You've probably had enough input on this issue and made your decision but one more thing you might consider- If you were to bid the job conditionally with the disclaimer prohibiting "low heat welding" or were to RFI prior to bid for clarification/removal of the spec. or had sufficient rapport with the contractor to establish a pre-bid review of the weldng spec so you could point out it's insufficient clarity, you might point out that the 1/2 pipes you would be attaching were going to have variations in gap and fit for the reasons pointed out above and to MINIMIZE heat input you would need to close those gaps as much as possible which would require additonal work, you might be able to make them see the light clearly enough they would review the welding spec or recognize your additional cost to meet it.  I would think a 3/4 ton chain comealong would be strong enough to pull the 1/2 pipe sections in to close your gap and reduce welding/heat input.  Doing so on a tower leg might be very impractical but even establishing that method for fit up might offer an offset in your pricing that could be worth looking at.  A lot would depend on inspection criteria especially for fit up.  It really bites to have to walk away from an opportunity because it condemnable from the start due to bad thinking on someone elses part but we all know, in construction, where there's confusion there's money.  Part of a professionals responsibility is provide clarity.  That can come at a cost.  Of course some opportunities you have to pass on if they are a sinkhole of energy. 
If it were me, I'd just let them know their galvanizing was going to get burned welding the legs on, period, live with it or redesign it.  Then weld it stong and not look back.  Is intermittent welding a possibility to "minimize" heat input?  Best of luck.
Parent - - By Cumminsguy71 (*****) Date 04-09-2014 22:12
Yeah, that's my plan is to contact the engineer and try and be as tactful as I can, but that is not a strong point in my personality! From my latest email it looks like I'll most likely get this job. It was strange that this was called out as I have done several of these in the last year and not once seen anything remotely like this on any other job. Definitely got lots of great input and shared Lawrence's comment with my Uncle, a welder of 30 plus years and my Aunt said he was laughing and said the Lawrence's comment pretty much summed it up! He also said that I should suggest super glue to attach the legs. Is being a smart arse hidden in the fine print for being a welder? :lol::lol:
Parent - - By JTMcC (***) Date 04-10-2014 19:20
Maybe I'm simple minded, but submitting  a bid or quote proposal, without clarity of the specs is inadvertent business suicide to me. Many dollars leaving my pocket cause I didn't quote to the specs, not a happy land there. And the contract(even a Purchase Order) holds the weight of law in the courts. You guys must know something I don't, or maybe don't want to know : ) The prime/owner always has higher priced lawyers than the little welder guy has.
How in the world does somebody do that? without getting burnt to the ground at some point. I've witnessed others enter that scenario several times and cleaned up afterwards several times. At a higher cost than if we'd got the work in the first place.

I must be out of touch.

JT
Parent - - By Cumminsguy71 (*****) Date 04-10-2014 20:40
Everything on the specs was crystal clear, mostly, 12" x 3/16" welds at the bottom and top, both sides of leg for 280 feet. Done it a lot in the last year plus. Then reading the welding notes, "use 70xx electrodes", "grind 2" past weld area all galvanized material". Then I read the "low heat welding" thing and go back to the word electrode, 70xx and figured there was a simple explanation since it appeared they were referring to the SMAW process. When I posted this things were in the works as to clarify this. Yeah, I admit, I had a bit of assumption going on, no you're not out of touch. I have 7 prints I am going over. I have 10 minimum prints from various engineering firms all dealing with towers and mods. Out of those 17 or more prints and "Welding Notes" I have not seen once anybody specify "low heat welding".

The only complication on this job is the "low heat welding" which apparently nobody that has responded has heard of yet. I told the engineer in an email that I welded a 1/2 piece of galvanized with a 3/32" rod at normal heat, 2" weld and still discolored the galvanized on the back. How they expect me not to affect the galvanized on a pipe with a wall thickness of .258" and produce sound welds is beyond me. The job in itself is simple, it's the addition of a high end college education by Tommy Neverbeenwelding engineer apparently.

Shawn
Parent - - By Smooth Operator (***) Date 04-10-2014 22:42
Shaun .........R.F.I. is what is called for (before bidding)....... Bidding a job that has "questions" that need addressed but not asking for "clarification" is asking for trouble........(no matter how inexperienced / F.O.S. a engineer, architect, owner or project manager is) they all have more weight than you.....Going forward the " expert" could have you regalvanizing in the field after your work is completed or paying for a expensive coating repair system.........Remember to C.Y.A..........
Parent - By JTMcC (***) Date 04-10-2014 23:25
What Smooth Operator said..........read it, learn it, memorize it, live it, tattoo it on your chest.
After the fact non compliance can be expensive enough to put a large business, out of business. Many millions have changed hands over these things, and I don't personally have a million to fork over : )
RFI's are your Best Friend and best defense always.
Keep all correspondence, have verbal determinations put in writing (and verbal is THE fastest way to reconcile spec with reality, bypass the many intermediates and talk to the EOR or his weld guy or his pipe guy or his structural guy, in person and have the EOR approve in the written word), a good engineer will do that without asking. If they don't, then require it if you want to keep your assets.
If they won't then just walk on by.
It's easy when you know the rules.
But the rules HAVE to be clarified before a price is offered otherwise you're playing a stupid, money losing game.

John
Parent - - By Cumminsguy71 (*****) Date 04-11-2014 21:23
Engineer does not get ahold of me then the work won't move forward. Thing with this stuff is the contractor has already bid the job and contacts me after they have given the price and won the job. They then call around for welding bids with the magic number in their head that they want to hear. So, in the end if the engineer does not respond to my question and give me an explanation or remove their "low heat" note, releasing me from any responsibility or liability then I won't do it.

This is a whole different world when it comes to working on these things. Your typical pipeline, structural stuff is monitored pretty heavy. These things from what I've seen, has a bit of a shady side to it. Engineer says coat with ZRC galvanizing, I've seen rattle cans of rustoleum cold galv used. Not my choice and I have spoken up about it but in the end there is nothing I can do about it.

Good input from all though, glad I didn't do any type of formal bid either, no legal trail! As I said though, unless the engineer can uncork this screw my butt won't be welding it with those expectations.
Parent - - By mechan (**) Date 04-12-2014 06:49
The GC is then already bound by the wonderful contract documents :twisted:. I mean there is obviously always the happy medium and every industry has its own idiosyncrasies. I do **** on a daily basis that makes me count to 10 and have OCD fits, but the pay check out weighs the jacked up way some things are done. If nothing else since the GC has already accepted the bid and as such the contract documents if the EOR won't clarify (which I would be surprised, but who knows) submit the RFI to the GC and also include in your bid package to the GC with what you plan to do. I would also put something in your bid to the effect of "any and all coatings or finishes damaged as a result of welding, cutting, grinding, or fitting to be repaired at cost by the GC or owner."
Parent - - By Cumminsguy71 (*****) Date 04-12-2014 13:48
I sent the GC the RFI as well as the engineer and called the engineer, left a message and have not heard back from him or GC. Got some little irons in the fire and got my fingers crossed with my lucky four leaf clover field on something else that would be much better. First come first serve, can't sit around here spending money waiting for others for work. Good education though on this, agreed I did have a fault with that simple "low heat" thing but didn't figure it could turn into what has been speculated it could. Lesson learned and thanks to all for pointing it out!!

Shawn
Parent - - By Superflux (****) Date 04-12-2014 14:00
"it could turn into what has been speculated it could"

Cummingsguy, what you are getting here is 100years combined experience from some of those who have faced "Worse case scenarios."
Most likely nothing would ever come of it. But in the real world, "Cover Thy Backside" is the Best Case Scenario!
I heard once that the rest of the world has 7 engineers to every lawyer and that, that statistic is reversed here in the US. Whether accurate or not, I feel this society and the small business man would be much better off with a few less lawyers and bean counters.
Read about a comedian the other day who was awarded 1.3 million clams for spraining his ankle on a Las Vegas stage.
Parent - By Cumminsguy71 (*****) Date 04-12-2014 23:01
CYA, that's for sure!

A few less lawyers in the world, guess we can always dream!

"what you are getting here is 100years combined experience from some of those who have faced "Worse case scenarios."

That's why I asked the "low heat" question here. Thought there was a chance that in my inexperience there was some miracle way to weld a piece of .187 wall galvanized pipe without destroying the galvanized on the inside that I was unaware of. Have not seen anybody point out that special process yet(that can be performed at elevations without a crane or basket, 220V outlets). Also have not heard from the EOR. So either he is pounding the pavement with labs and CWI's in his area trying to find out what it is I am supposed to do or they decided to go with another welder who did not ask the question to cover his arse, or more simply, they found one who does not care or didn't read the "Welding Notes".

It's all good though, continuing the bushy bushy shake!!! I just want to weld man, just want to weld....:lol::lol::lol:
Parent - - By Metarinka (****) Date 04-10-2014 22:04
what do you mean "perfect world" my suggestions always makes sense. :wink:

I wasn't trying to imply that you could squeak by just by running a really fast weld. I agree that trying to increase the process efficiency for field welding work is a not gonna work, there is definitely a practical limit to travel speed due to fitup and what someone can reasonably be expected to do, and it's probably not fast enough to make a big difference in heat input. Besides without a clear definable goal, how will you know you've succeeded? "low heat input" just means you lowered it.  You can make the lowest possible heat input weld, but if your welding on a full gas tank, it's still gonna catch on fire.
Parent - - By ssbn727 (*****) Date 04-12-2014 07:50
It's all Good...

You should get out more.:grin::lol::roll::smile::twisted::wink::cool:

Respectfully,
Henry
Parent - - By Cumminsguy71 (*****) Date 04-14-2014 21:47
Well, contractor emailed and said this job has been put on hold. They did not specify why but said that there were some issues that needed to be addressed. Since I have not heard from the engineering firm about my RFI and since they were in meetings this week I can only presume that my question might be the reason behind this!

I guess we'll see what happens!
Parent - - By kcd616 (***) Date 04-15-2014 01:38
Shawn,
they are, watch your back
and you might raise your bid:wink::evil:
hope this helps
sincerely,
Kent
Parent - - By Cumminsguy71 (*****) Date 04-16-2014 11:19
The contractor is aware that things are being changed in some way so when everything is straightened out they will ask me to resubmit my bid after reviewing whatever has been changed.

Shawn
Parent - - By kcd616 (***) Date 04-16-2014 11:54
we are here if you need us
sincerely,
Kent
Parent - - By Stringer (***) Date 04-16-2014 12:11
Since a lot of my work is light guage stainless I'm always asked to weld without getting anything hot. I tell them to get me some of that new transvaginal mesh and we'll try to make that work.
Parent - By Milton Gravitt (***) Date 04-16-2014 12:47
Stringer, I think they had a recall on that transvaginal mesh. LOL

                       M.G.
Parent - - By jwright650 (*****) Date 04-16-2014 12:47
Remind the spec writer or engineer that the galvanizer maintains the zinc bath around 850°F to keep the zinc molten when dipping a large object and still have the zinc wet out over the part. IOW, the zinc is molten at a lower temperature than that and to weld two pieces of steel together, it will get hotter than a temp where the zinc will remain as a solid.
Parent - - By Cumminsguy71 (*****) Date 04-16-2014 22:17
That's good to know. This is definitely a case of, heat the frying pan and put the butter in but don't let the butter melt type of situation.
Parent - - By Superflux (****) Date 04-18-2014 13:06
Fill the Monopole full of water and weld away.
See how easy that was???!!!!
Parent - - By Cumminsguy71 (*****) Date 04-18-2014 13:58
Well, it's actually a self supporter so you have 2o foot sections with three legs. Each leg has a flange top and bottom, no access to the interior of the pipe leg. I suppose that if the engineer came up with some way to drill a hole in the top, fill the leg with water and then weld. Then drill a hole in the bottom of the leg and let the water drain it could be done. Now, start this process at 0 feet on 6" pipe legs up to 40 feet. Then jump up to 80 feet and start the process over and go up to 280 feet, I think that's where we stopped, maybe 240ft.

It could be done I suppose. Whether the cell company is willing to pay for this modification so they can hang a few new antennas would be the other issue. Time to do this as I'm sure they would not allow us to water fill the legs then weld away then drain. Still wouldn't guarantee that the coating would be factory perfect on the inside.

We'll see what happens and what they come up with.
Parent - By Tommyjoking (****) Date 04-20-2014 03:12
The engineer is just making stuff up....... "low heat welding"

Why not just be clear... "Minimize heat input to preserve galv. on back side"

thats nuff right there.
Up Topic Welding Industry / General Welding Discussion / Low Heat Welding

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