Shielding Gas Manifold System Leaks

By TimGary (****)

Date 08-10-2016 20:29

One of our shops is fairly large, about 300K+ square feet with 40' - 50' high ceiling.
We have a shielding gas manifold that runs throughout the ceiling, with drops at most columns and some in-between, maybe 40 drops all together to feed about 100 weld cells.
The manifold is typical carbon steel screw pipe, handling 90/10 Argon/CO2 from bulk liquid tanks, at 80psi holding pressure.

I've determined through timing the cycling of the mixing station, while no one is welding, that the system is leaking 350 cf of gas per hour, or about $10K worth of shielding gas per month.
Each of the system drops from the ceiling has a shut off valve just above the weld cell connection points, so I shut all of them and re-checked the mixer. This caused the time between cycles to double, which means that half of my leaks are on the floor, and half are in the overhead.

I can find / fix the leaks on the floor fairly easily, but the ones in the overhead are tough to get to.
I really don't want to pay a couple of maintenance techs to spend the month of August in a boom lift, tracing and leak testing pipe in the ceiling of a weld shop.

A wise guy once told me that laziness is the real father of invention, which must be true, as I've had a brain fart which is that if there's a considerable leak in the overhead system, I should be able to see it from the floor if I use an infrared thermal vision scope.
I'm thinking this because the gas, which is coming from super-cooled liquid, has to be cooler than the hot air rising to the ceiling, so surely the temperature difference would be noticeable. Probably won't be able to spot a small leak, but should be able to see a large one...
If this is true, then at least the finding the leak(s) part of the job will be much simpler.

So, being a cheap skate, I asked around to borrow somebody's infrared hunting scope, but no one has one (or will loan it to me).
Then I started looking on line for cheapest options:

http://www.flir.com/hunting-outdoor/scouttk/
https://www.amazon.com/Seek-Compact-Thermal-Imager-Android/dp/B00NYWAHHM

Then I found that someone already stole my idea and made a thermal gas leak detection specific camera:
http://www.flir.com/ogi/display/?id=55671

However, my Boss, who is a cheapskate as well, won't buy a damn thing unless I can show him that it will work before he cuts the check, which finally brings me to a question...

Has anyone used thermal imaging equipment before in a similar manner, to check for argon/CO2 leaks, and what was your experience?

Thanks,
Tim Gary

By 522029

Date 08-10-2016 20:35

At $10,000 lost every month, a thermal image system or two guys and a bottle of bubbles is a no brainer.

Griff

By TimGary (****)

Date 08-10-2016 20:51

I hear you!
You'd think I wouldn't have trouble risking $500 to help fix a $10K problem quicker, but no.... gotta justify the cost first...

By Lawrence (*****)

Date 08-10-2016 20:53

Even with a 50' ceiling, if you shut *everything* down. You might be surprised how loud a leak is.

an Airgas guy also told me about directional sound tools, used just for the purpose of finding gas leaks overhead.

By Milton Gravitt (***)

Date 08-11-2016 01:32

How long has the piping been installed? Did your gas supplier install the pipe if they did you might be able to work something out with them. Just my thoughts on it but $10,000.00 a month how many testers could you buy with that one month.

M.G.

By mcostello (**)

Date 08-11-2016 01:51

$10,000 a month would make any boss I had eat Tums like M&M's.

By TimGary (****)

Date 08-11-2016 12:18

I went to my AIRGAS folks, so far, they've only recommended a hand held sniffer....
I'll ask about this.

Thanks,
Tim

By Trackergd (**)

Date 08-25-2016 19:31

It is possible to use a gas sniffer taped to a long extendable pole (like they use to paint houses) to reach the piping? If the shop is quiet, you should be able to hear the alarm tone when it finds a leak.

I have used thermal cameras before, but only for search and rescue where I am looking for a warm body at night...

By Lawrence (*****)

Date 08-25-2016 20:28

Tracker indeed !

By Trackergd (**)

Date 08-26-2016 10:20

I can't see the lost persons tracks very well at night, even with flashlights, so I switch to night vision and thermal and stay off the trail so as not to destroy the prints for my daytime evaluation and the dog handlers. :razz:

By 522029

Date 08-11-2016 13:16

When I worked in the PowerHouse at my work (before I retired), we used an "ultra-sound gun" to check for leaks in the air and steam lines. It was very useful in checking condensate trap operation.
I forget the specs but the ultra sound could hear extremely small leaks and mechanical functions of various devices.
It's use was necessary because of the extreme noise in the PowerHouse.
They ranged in price from a couple of hundred dollars to outrageous.

HTH
Griff

By 52757

Date 08-11-2016 11:31

Our shop used plastic line before the code changed and required copper. Back then one of the inspections areas was in what used to be a weld cell at one time. It was right on the other side of a wall from the shipping area. For a year, every time I was in that area I always felt a draft, I chalked it up to being by the overhead shipping door. Then one day when nobody was working and it was quiet in the shop, I heard the hissing sound, here the pipe about 30 ft. above had a big crack in it. It was big enough that you could actually feel a draft from it! For a year at least, 24 hours a day if was blowing 90/10. I wonder what that cost!

By TimGary (****)

Date 08-11-2016 12:12

Yup, I figure we've got one or two of those type issues going on, which is why I'm thinking it might show up on a thermal scope.
We've already found one open line on the floor. It was a disconnected line that had been going to a welding machine. just coiled up on the column, blowing gas 24/7. When the area Welders were asked about it, they just shrugged and said "Yeah, it's been like that for a while."
I'm told we occasionally have someone hook up an air tool to the shielding gas line, thinking it's compressed air...

M.G. -
The manifold was installed by the building contractor about 15 years ago. No joy there as it has not always leaked like it is now. We've done a lot of moving things around in the last year, and I'm pretty sure created our own problem.

Tim

By pipewelder_1999 (****)

Date 08-11-2016 16:18

Thus the reality of WELDED vs mechanical fittings. Hmmm 10k per month, wonder how many months to pay for REAL piping? :)

Can you reduce your manifold pressure a bit to reduce your losses in the meantime or are you using flow control at the stations that requires the pressure you are running?

Gerald

By TimGary (****)

Date 08-11-2016 17:01

I hear you Gerald.
If I ever have the opportunity to build my own shop, all of the piping will be brazed copper...
Nope, can't reduce the pressure, due to flow control and working volume.

Tim

By kcd616

Date 08-12-2016 01:46

Tim
have the boss
pay $$$$$$$$$$$$
then I fix it
costs $$$$$$$$$ to fix stuff
for you
free
anybody else
costs $$$$$$$$$$$$
sincerely,
Kent

By kcd616

Date 08-12-2016 15:37

btw
use stainless 308 1" sch 40
I would weld it slip on fittings
could use threaded
and could go smaller on the pipe
just my thoughts
sincerely,
Kent
P.S.: tell the boss he owes me :evil:

By Metarinka (****)

Date 08-22-2016 17:36

I've used an IR camera for looking for gas leaks. Just not on argon, I don't know it's emissivity and how big of a leak it would have to be to see it. If it doesn't work return it. I think a sniffer is more reliable especially on the low volume leaks.

By Trackergd (**)

Date 08-26-2016 10:26

Tim,

It also occurred to me that checking the valves first might save time. The stem packing dries out on the older style valves and the gland nut needs to be tightened or the valve replaced. Not sure how old the manifold is and if it has newer ball valves or the older gate or globe style.

We have a 35+ year old compressed air manifold in this place. When it is quiet, it sounds like we have a snake farm. Lots of hissing, notably from the old valves in the overhead.

By fschweighardt (***)

Date 08-28-2016 15:36

The gas isnt cold, once it gets into the building

By mcostello (**)

Date 08-29-2016 02:18

The gas escaping would tend to cool down the leaking part.

By fschweighardt (***)

Date 08-29-2016 02:32

Yeah it would,but not much. It would have to be a pretty big leak to get much JT cooling

By TimGary (****)

Date 08-29-2016 12:09

Yup, I hear you guys.
The gas warms up pretty quick, after leaving the bulk tank.
However, as it's August in Tennessee, in a weld shop, I guess that the air temp just below the roof is at least 120F.
I would think that the shielding gas plume coming out of a substantial leak would be less than that....
I tried a Fluke thermal imager:

http://en-us.fluke.com/products/infrared-cameras/

with no luck. Just couldn't see anything, even from close up.

I've set up a product demo with Flir, to check this out:

http://www.flir.com/ogi/display/?id=55671

This is a different kind of animal. It's supposed to be able to "see" CO2, even at our 10% mix amount. Maybe it will work....

In the mean time, we're manually fixing leaks and working on behaviors.
It seems that some folks think it's OK to run a pneumatic sander off the shielding gas manifold....

Tim

By 52757

Date 08-29-2016 14:54

I'm confused now. You mean that is NOT what that line was for???? :) :evil:

By TimGary (****)

Date 09-01-2016 20:49

Just in case anyone is interested...

The FLIR GF346 camera works. It can see the CO2 in a 90% Argon / 10% CO2 mixed gas quite readily.
The only down sides are:

You have to be somewhat close, 10 -15 feet max with a fixed lens. (however the sales rep tells me a telephoto lens attachment will increase the range).
And the $90K price tag...

Tim