Welding Helmet

[Matt@RFR]

It has to do with the sensitivity of the sensor on the hood. When you strike a TIG arc, it starts at extremely low amperage and works up from there as you ramp the pedal up. Most cheap auto hoods won't pick up low amperage stuff like that....so it might not darken until the arc reaches a certain amp number.

[parsonsj]

Yeah, what Matt says makes sense. It was OK when I was welding my cage, but it wasn't OK when I welded my headers.

jp

[sinned]

What's the difference between mig and tig that would require different hoods? Is it only the different number shade?

TIG arc is much brighter and I have never seen an auto darkening helmet that actually worked well enough to TIG for any length of time with seeing spots for an hour afterwards.

When you strike a TIG arc, it starts at extremely low amperage and works up from there as you ramp the pedal up.

See, now I was taught differently. I mash the pedal then back off to an amperage I am comfortable with....yes my instructor was a "real" welder by proffession.

[Matt@RFR]

I mash the pedal

Two words: Thermal shock.

[sinned]

Two words: Thermal shock.

I guess with TIG it is somehow different than with a stick or a MIG...they both hit wide open right from the get.

[Matt@RFR]

You're absolutely right. And that's why those two processes (in most cases) are sub-par to TIG when no other precautions are taken.

If you get a chance, look in any AWS (American Welding Society) welding spec. For all things structural, when using MIG or stick, there's a minimum pre-heat temp to avoid thermal shock. Further, there's maximum inter-pass temp specs for each filler/base metal combo.

[parsonsj]

Yeah, I go with just enough pedal to get the arc started ... then I slowly ramp up as the puddle forms. I'll probably wear out my high frequency circuit faster, but that's how I learned to do it.

jp

[sinned]

I should have noted that anything with a structural integrity spec I pre-heat with oxy-gas. Actually, most of the stuff we weld is pre-heated as it is 2-4" thick (and all structural).


I also have the machine set at the maximum amperage I will need, it kinda sounded like I was hitting the pedal with full amperage and adjusting down.

Back to the subject of helmets... I have a pair of goggles with #8 lens' that work pretty good for light duty MIG work, very unobstructive but offer no UV protection to the rest of your face.

[toxicz28]

http://www1.mscdirect.com/CGI/NNSRIT...07199&PMT4NO=0

Comfy and cheap. Worst case scenario is welding galvanised steel all day....you're dinner will taste funny, but no ill-effects.

Wearing one of these for welding well prepped steel is in no way necessary.

Matt,

You're right on with the respirator selection, but dead wrong about not using one for well prepped steel.
Well prepped steel releases almost as much toxic crap as dirty steel. The mineral content of flux (7018) is amazing. The alloy content of welding wire is up there too.And when you weld with it and don't use a respirator, you're breathing all of that in.
Long term exposure leads to "Parkinsonism". Central nervous system damage, the shakes, respiratory problems,etc. The sad thing is is that the electrode mfr's have known about this for 50+ years and have done nothing but hide it.
I know now you're going to say "I weld with MIG/TIG, so the flux is not an issue!" True, but now you have to worry about argon poisoning. If you know any "old-timer" steamfitters or boilermakers, ask them about it. Respiratory problems, and if left unchecked it could lead to brain damage from lack of O2 to the brain. You can't use a fan, because it blows the argon away resulting in poor weld quality. So where does that leave you? Ideally, a forced air system is your best bet. PAPR (powered air purifying respirator) is just as good, unless you're welding galvanized in an enclosed space(then you need forced air). They even sell auto dark sheilds with PAPR built in. $1100 is about what they cost the last time I checked the price.
I could go into detail about galvanized steel, lead covered steel(even if you think you got it all off, it's still there) and more, but I think you've all read enough of my ramblings. So I'll close it with this.
Just like eyes, you only get one set of lungs. If you're young and just starting out, get a respirator right away. YOU ARE NOT INVINCIBLE! If you're older and your lungs don't hurt yet, start wearing a respirator now before it's too late.

[Matt@RFR]

Toxic, I was aware of Argon poisoning, but only where it pertains to closed environments, EG: In the bottom of a tank, argon (since it's heavier than air) will accumulate, purging the oxygen from the tank, and eventually sufficating the weldor. I do know of one guy that this happened to.

I wrote you a PM. We'd all like to know more about this subject! This type of information is very hard to come by, and it certainly isn't taught in the workplace....

[KWIKND]

FYI on the respirator.

Mayo Clinic analysis reveals connection between welding, brain damage
A Mayo Clinic case series analysis has pinpointed for the first time, syndromes associated with toxic damage to the brain and nervous system from manganese fumes generated during welding. The analysis also revealed that all affected patients shared a risk factor: welding with inadequate ventilation.

Due to ethical concerns, human trials with manganese fume exposure are not conducted. Most information about welding and health hazards is gleaned from animal studies or from analyzing patient cases in which exposure has occurred.

In the Mayo analysis, the researchers examined medical records from eight patients referred to the clinic between 1999 and 2005 for various nervous system complaints. All of their MRI scans showed an area of increased T1 signal intensity in the basal ganglia region of the brain, which appears as a bright spot on the MRI scan and is a biological indicator of manganese accumulation. All were men involved in welding for one to 25 years before symptoms developed. Initial symptoms varied, but multiple symptoms developed over time, including cognitive impairment, headaches and tremor in six of the patients, and balance problems in five patients. Each patient was diagnosed with neurotoxicity from welding fumes after undergoing testing appropriate to the patient's complaints, such as blood and urine testing, brain MRI, and psychological testing of intelligence, aptitude and personality traits.

The increased T1 signal in the brains of the eight patients as revealed by MRI is an uncommon finding in brain imaging, according to Keith Josephs, M.D., Mayo Clinic neurologist who spearheaded the analysis. This is the first case series of welders with this abnormal signal highlighting such widespread neurological impairment.

Dr. Josephs says previous case reports have linked manganese fumes generated by welding with various symptoms, but none has identified the syndromes or actual diagnoses, except parkinsonism. The syndromes identified in the Mayo Clinic analysis are:

Parkinsonian syndrome -- a form of parkinsonism, a group of diseases characterized by tremor, rigidity or stiffness, slow movements and difficulty maintaining balance. This syndrome can look like Parkinson's disease, yet is distinct.
Multifocal myoclonus -- lightning-fast twitches that occur all over the body.
Vestibular-auditory dysfunction -- problems with balance, hearing or dizziness.
Mild cognitive impairment -- concentration impairment characterized by a lack of attention. This is different from the mild cognitive impairment which is a precursor condition to Alzheimer's disease.
Dr. Josephs encourages physicians to think broadly regarding symptoms potentially associated with welding and manganese fume exposure. "When physicians consider welding and manganese exposure, they often think of a symptom known as '**** walk' -- a staggering, strutting gait. Our analysis shows that symptoms are often more subtle. Damage from manganese exposure is also more common than we think."

A common factor with all eight welders studied, according to Dr. Josephs, was inadequate fume-protective measures. This provides further evidence that unprotected welding leads to neurological damage.

"An important finding from our case series analysis is that these patients were not only all welders, but all had a lack of ventilation," says Dr. Josephs. "They didn't have a mask or were welding in confined spaces."

Dr. Josephs does not advocate against welding; rather, he encourages prudent safeguards. "Protection is the key ingredient here," he says. "I think that if you have good protection and follow the U.S. Department of Labor's Occupational Safety and Health Administration guidelines for protection while welding, you're probably safe."

Mayo Clinic physicians treated seven of the eight patients with low-manganese diets and one with chelation therapy with ethylene diamine tetraacetic acid, a crystalline acid therapy designed to bind the acid with the excess metal in the body -- the manganese -- and neutralize the toxic effect.

Dr. Josephs explains, however, that there is no "home run" treatment for manganese neurotoxicity. "We don't have enough evidence that diet is absolutely the way to go; while diet modifications can decrease oral intake of manganese, their manganese exposure is due to another form of intake: inhalation. Chelation therapy has the inherent risk of removing metals important to the body."

Many of the patients studied still had symptoms after they stopped exposing themselves to welding fumes, leading the Mayo neurologists to postulate that the damage invoked by manganese exposure may be permanent. "It seems to be static or progressive, not reversible," says Dr. Josephs. "I think the best option is removal from welding."

The findings are published online at www.neurology.org and will appear in the June 28 print issue of Neurology.

Sorry so long but worth thinking about.

Dan