Has anyone fully explored the topic of hermetically sealed filler metal containers?
Too frequently we receive low hydrogen electrode in cardboard boxes (with the electrode wrapped in plastic). Our PO states the containers must be hermetically sealed; and the MTR indicates compliance.
According to SFA 5.1 and 5.5, as long as the packaging passes a simple immersion test, it is considered "hermetically sealed". The test involves submerging the container in hot water. The test is acceptable as long as any stream of bubbles that occurs does not last more than 30 seconds. Truthfully, when I read this, I had to laugh aloud. Than I got pretty pissed. What kind of test is that?
Personally, I would reject any package that is not metal, and produces the audible sucking sound (of air inrushing) when opened. However, if the package passes the submerged water test, it could be argued that it is acceptable.
How can this be so? I was under the impression that any atmpshere coming into contact with the flux, could cause Hydrogen absorption. How can wrapping the electrode, in what amounts to Saran Wrap, be considered protecting it from the atmosphere?
Any and all comments are appreciated.
Charles.
EDIT: I would like to modify my initial description slightly: The container ends have metal inside, covered by cardboard. The entire package is lined with plastic. I still think it's unsat, but it's not quite as bad as my initial description.
The A5.5 specification sets limits on the moisture content of low hydrogen electrodes packaged in hermetically sealed containers. These limits range from 0.2 percent to 0.6 percent by weight, depending on the classification of the electrode. The higher the strength level, the lower the limit on the moisture content. The reason for this is that moisture is a primary source of hydrogen, and hydrogen can produce cracking in most low alloy steels, unless high preheats and long, slow cooling cycles are employed. The higher the strength of the weld and the base metal, the greater the need for low moisture levels to avoid cracking. Exposure to high humidity (in the range of 70 percent relative humidity or higher) may increase the moisture content of the electrode in only a few hours.
SW,
I believe the moisture content testing you refer to is not related to the issue of requiring packaging in sealed containers. I could be wrong, but it's my belief that the mfr only has to do that test to prove they are capable of meeting the diffusable hydrogen absorption limits specified by the code. Once they have proven that, it is their responsiblity to handle and package the rod according to specification.
Other construction codes limit exposure to atmosphere. Depending on the strrength of the filler, low hydrogen electrode is only allowed outside the original "hermetically sealed" container (or rod oven) for a specified amount of time, regardless of the atmospheric conditions (ie -actual relative humidity). If the mfr attaches a suffix indicating the actual diffusable hydrogen rating, that time may be adjusted.
So my contention is this: If the rod is only allowed to be exposed to the atmosphere for (lets assume typical E7018) 4 hours once removed from the original packaging or a rod oven; how do you factor in the situation where the rod packaging may leak air slightly, but still pass the 30 second stream of bubbles test? On the one hand it passes the Section IIC requirement (SFA 5.5), but on the other, it is still admitting air, however small that amount may be. If the container is left on the shelf for too long, it will still be considered sealed, but may contain rod that has absorded too much hydrogen.
Thanks for your interest.
Charles
Charles,
I'll explain you what kind of a test is that.
First of all, that test applies only to metallic boxes. In metallic boxes the electrodes are loose, i.e., they're not wrapped.
The standard you mention admits that the metallic box might be not totally hermetic, i.e., there might exist a tiny little hole in it that, always according to the standard, won't be harmful to the integrity of the electrodes. In other words, the hole is so little that the outside air that might get into the box won't do any damage to the eletrodes.
Now, what's the maximum allowable hole diameter? Instead ot telling you to measure it, which is not an easy job, the standard tells you to dip the metallic box into hot water, whose temperature the standard should specify.
What happens then? Due to the good old gases law, the air inside the box expands and gets out the box through the tiny little hole, making a chain of bubbles.
If the bubbling lasts 30 seconds or less, the standard admits that the hole is sufficiently small so as not being dangerous for the quality of the electrodes.
Of course this test is not feasible for cardboard boxes. In this case, you should rely on the supplier's good name and reputation. If you have any doubt, buy a box of eletrodes and have a chemical lab make an analysis of the moisture content of the electrode coating. There's an AWS standard, whose number I don't remember, that specifies how to do that test.
Giovanni S. Crisi
Sao Paulo - Brazil
Mr Crisi,
I have to respectfully disagree with you on this. The specification makes absolutely no mention of the packaging being metal. Furthermore, the specification clearly states that the packaging must be hermetically sealed. I think the confusion comes from how the specification defines hermetically sealed: ...as allowing a slight amount of leakage.
I understand the principal of the test but disagree with the idea that it works. It doesn't account for time. If any air leaks into the box, it is suceptible to transferring moisture. Without beating this thing to death, I'll simply add this: If the package leaks a small amount of air in, and somehow the package becomes compressed and forces the air out, it may leak more air back in. Over time, the cumulative effect may be that the flux has absorbed more hydrogen than it is supposed to have.
I know that sounds like I'm looking for a reason to reject the material. Enough manufacturers package the electrode in metal that is truely sealed, so that I should not have to worry about this in any fashion. Even 6010 is packaged by reputable manufacturers in metal.
Packing low-hydrogen elctrode in anything but an obviously sealed container is unsat in today's market. We won't be accepting any more if it comes in cardboard.
Charles.
Charles,
I understand your doubts. However, let me ask you a couple of questions:
1. Do you think that a cardboard box can be submerged into hot water without getting spoiled? In my opinion, no, that's why I said that the test applies only to metallic boxes.
2. The standard clearly states that the container must be hermetically sealed. Now, if you dip it into hot water and bubbles come out of it, is it really hermetically sealed? In my opinion, no, that's why I said that the standard has a tolerance which is to be measured by the time the bubbling lasts.
Giovanni
Giovanni-
I have seen electrodes sealed in plastic and then enclosed in cardboard. I assume the cardboard is there to mechanically protect the seal which is the plastic. I would assume then that a fair test would be to remove the cardboard and test the plastic inner package. I have seen small quantities packed in plastic tubes sealed with tape, which could be tested this way. I have not seen plastic impregnated paper (such as commonly used to package milk in this country) used but see no reason why it would not work to package electrodes. It could also be tested this way.
I agree that any bubbles indicate lack of hermetic seal and continue to maintain that the test is wrong. The length of time that the bubble stream lasts will have an inverse relationship to the size of the defect. A really small hole could bubble for a long time (like a slow leak in a tire), a large hole will let the pressure equalize quickly and the bubble stream will end sooner (like a blowout in a tire). I fail to see why any allowance is made for leakage. It isn't that hard to make a sealed container, look in any food market, cans, plasticized boxes, plastic bags, all sealed, generally to prevent contamination by microbes which could spoil the product and make it unsafe to eat. Given reasonable handling they virtually never fail.
Bill
Charles-
In addition to mechanical deformation of the package temperature cycling, an almost sure thing in a storage shed on a construction site, could also cause the leak to breathe.
Bill
Some thoughts-
Surely the chemists of the world could supply an indicator that would show if the rods had ever been exposed to humidity. If that were included in the package the problem would be solved.
If the rods are in a sealed plastic bag which was initially partly evacuated the plastic should be still clinging to the rods. If it leaks it would go slack.
Many things which would be damaged by contact with the outside world are packaged in various plastic/paper packages. Examples include ultrapasturized milk, US army MRE's, and bags of portland cement. The packages can be quite reliable.
It seems to me that the bubble test is wrong- imagine the test is performed on a container with a microscopic hole. Then imagine the same test with an arbitrarily larger hole. All other things being equal the air will escape faster through the larger hole, the pressure will equalize sooner, and the bubbles will stop. Thus it seems that the standard should be- If any bubbles emerge then they must continue to emerge for at least 30 seconds. For my mind though the standard should simply say - no bubbles should emerge.
Bill
You may be onto an excellent idea for how to make your first million (assuming of course you haven't already earned it).
Thanks.
Charles
Not even close to a million yet.
Bill
What Bill says is consistent.
Charles, why don't you take a look at the standard and check whether it actually says that the bubbling should last 30 seconds as a MINIMUM or as a MAXIMUM?
Giovanni S. Crisi
Mr Crisi,
ASME Section IIC, SFA 5.5, paragraph 22 - Packaging:
22.1 - Electrodes shall be suitably packaged to protect them from damage during shipment and storage under normal conditions. When electrodes are packaged in hermetically sealed containers, the type of hermetically sealed container shall be capable of passing the test specified in 22.2
22.2 - For test, a representative container shall be immersed in water that has been heated to a temperature of at least 50F (28C) above that of the packaged material (room temperature). The container shall be immersed so that the surface under observation is 1 inch (25mm) below the water level and the greatest basic dimension is parallel to the water surface. A container with a steady stream of bubbles that lasts for 30 seconds or more does not meet the requirements of the specification.
In my opinion, passing this test does not mean: (1) the container is hermetically sealed and (2) the electrodes within will maintain their low hydrogen status under normal storage conditions.
However, electrode manufactures in compliance with the specification may ligitimately claim their product is low hydrogen.
For an organisation like ASME to allow such a loose definition of hermetically sealed, for a product used as it is, is just mind boggling.
Charles
In my little world it is simple. If the welding rod can is damaged my supplier gets it back. If the welding rods are low hydrogen and not in a sealed metal can my supplier knows he has no reason to send them to me because he will be getting the unsealed rods back.
this may be an issue out of my league, but i often get spools of mig wire, small and large, which are wrapped in plastic. often during shipping, or on display, the plastic is broken, punctured, ripped, and this is from reputable welding retailers. i deal mostly with steel, aluminum and stainless. it seems that there must be contamination of the filler just waiting to be sold. and when i load that 10 pound spool in my machine and it takes a few weeks to burn it up, how is it at the end of the spool? is it practical to put it in the oven every night?
This is an oft discussed topic. I am not aware of any of the construction codes that require FCAW filler metal to be protected the same way SMAW low-hy elctrode is.
Most of the time, the filler is fine unless it shows some flaw during use (ie - unexplained porosity).
I think as long as you keep the spool out of the weather, you should be able to use it unless the job specification has other requirements.
Charles
Chall,
Research FEMA 353 Part I paragraph 3.3.3 & Part I Appendix D.
In lieu of testing the moisture content, you must use a type of rod oven for your wire if welding is suspended for more than 8 hours and then if the entire roll is not consumed with in an accumulated time of 24 hours of exposure the roll cannot be reused, however I think redrying is permitted if you can prove the moisture content has not exceeded the allowables.
John Wright
JW,
Thanks for the note....... I diddn't realize this stuff was available online.
http://www.fema.gov/pdf/hazards/353ch1_3.pdf
FEMA-353
Part I
3. EXECUTION
3.3.3 Electrode Storage and Exposure Limits
FCAW electrodes shall be received and stored in the original, undamaged manufacturer packaging, until ready for use. Electrodes in packages that have had the internal plastic wrapping damaged shall not be used for welds in Seismic Weld Demand Category A or B. Modification or lubrication of an electrode after manufacture is not permitted, except that drying is permitted as recommended by the manufacturer.
The exposure time limit for all FCAW electrodes shall be based upon the results of tests as prescribed in Appendix D. These tests may be conducted by the electrode manufacturer or supplier, by the Contractor, or by an independent testing agency or laboratory with suitable equipment.
In lieu of testing, when welding is to be suspended for more than 8 hours, electrodes shall be removed from the machines and stored in an electrode wire oven maintained at a temperature between 250o and 550o F, or as recommended by the manufacturer. Electrodes not consumed within 24 hours of accumulated exposure outside closed or heated storage shall not be used for welds in Seismic Weld Demand Category A or B. Electrode spools shall be identified to facilitate monitoring of total atmospheric exposure time. FCAW electrodes that have been exposed for periods exceeding an accumulated 24 hours may be dried if manufacturer’s testing and recommendations show that drying is effective at removing moisture and restoring electrodes to their designated diffusible hydrogen level.
Appendix D
http://www.fema.gov/pdf/hazards/353appd.pdf
Wow,
FEMA certainly has taken some of the filler metal concerns to a much higher level of control.
There is a ton of info available on line. Although we don't do seismic projects, it's nice to review the info for applications that may require a higher degree of control or awareness.
It also probably represents a glimps of where the welding industry may be headed in the future.
Thanks for the heads up.
Chall,
This seems to be something structural engineers/designers on the East Coast are using more and more as time goes on. We got bit on a job in PA several years back with this guideline. It turned out that the engineer had no clue what it was but saw one of his collegue's specs on a West Coast job and thought it would be neat to have specs like that on his building. He all but admitted this to me as I was questioning him on his standard moment details in the contract docs, which didn't jive with the FEMA guidelines at all. He finally backed off and took out most of the FEMA requirements and relaxed the inspection accordingly due to the excessive cost that was now impacting the completion of the owner's job. This job put the erector on that job out of business, because he didn't add anything in for all the extra work he had to do removing backing bars and qualifying his guys for overhead welding to apply the addition fillet welds and such. It got ugly and went to court for all parties involved just because of the spec writer adding the words "BOCA 1999" and "FEMA 350" in the reference docs.
John Wright
ON EDIT
this post is in reply to superk, but this MB won't insert behind that post for me.
by definition, mig wire is solid. what is the issue, as nothing is present that will absorb miosture?
granted, wire must not be allowed to rust, or collect dust, as this clogs the liner quickly.
If we had to put our mig wire in an oven I think the plastic spool would melt.
Bill
There have been previous posts on this topic but I have not been able to find them with the "search" functions. (Must be an operator-to-machine mismatch)
GMAW, FCAW, GTAW and SAW electrodes are not required to be hermetically sealed by the manufacturer; at least not by D1.1 and D1.5. The processes are considered to be low hydrogen by nature. The plastic wrap on these electrodes is merely to prevent excessive moisture, dirt, and even oil or grease from fouling or rusting the filler metal.
It can be a condition of a PO to reject any welding consumables received with the packaging damaged. Or as many companies do, the contents could be examined and accepted if no contamination is found. (Of course, everyone should realize that not all contamination is readily visible, so let the buyer beware)
Low hydrogen SMAW could be baked prior to use if suspected to be contaminated with moisture. (Don't forget the penetrating abilities of products like WD-40 and that if contaminated with oil, then the rods should be considered as junk). However, to me, having to bake the rods because of contamination is a bit like towing a brand new car home and installing an engine before you can drive it.
Whether it is required or not to have a package air tight, or how many bubbles can leak out in 30 seconds, I would think that reputable electrode manufacturers would consider customer appeal. As was said above, there seems to be no reason that plastic welding rod packages could not be vacuum sealed by the factory. When you open a vacuum packed container there is no question if the seal was intact or not.
I have heard rumors that some electrode distributors buy up surplus welding rods and re-package them with their own labels. If true, then maybe questionable packaging is a good way to cull questionable electrodes? While is is possible to find bargains, the general rule is that you get what you pay for.
Chet Guilford
CHG,
You can buy coffee vac-packed, why not welding rods? :) We use Lincoln SMAW filler and they still use 50# metal cans that are sealed.
John Wright
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