Rank: Forum user 
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Hi Guys,
Having so many issues with confined space and TIG welding process at present.
I have be researching it and numerous literature warns that TIG welding should not be completed in a confined space due to Argon gas possiblity of leakage, or build up and rapid asphxiation of persons in the Confined Space. O2 monitoring is complete prior to entry and continually during entry.
Forced ventialtion into the space is being rejected as this will affect the shielding gas and reduce the ability to complete the weld.
Also the temperatures are approx 24- 32oc in the confined space due to adjacent vats and temperature emitted from them. Makes it difficult environment and difficult to wear PPE. Concern is RPE for confined space welding on Stainless steel.
And the thing to top this off is these vats are very old, have small top sided man hatch entrance and a very low ceiling directly above the man hatch. It is nearly impossible to fit a rescue winch in this space and the internal construction of the vat has spindles and paddles so any lifeline and retrivel is impossible to fit as the line will entangle on the structures and it would be impossible drag a person to under the hatch.
I have contacted the manufaturers and they are working on solutions but have no real feedback to me at this stage and i'm really in awful position. My assessment identies control measures for Isolation and Lock Out of 3 main energy sources and hazards, we have PTW system and trained personel only doing permits and jobs. 02 meters for pre-entry and continous monitoring, cool vest and temperature probs for internal temperature readings and anti slip mats.
I can't decide on the TIG welding, rescue and First Aid provision at this stage and costs of engineering solutions are out this world as this applies to 9 identifical equipment.
Any advice guys......:(
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Rank: Super forum user 
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Safetyman, http://www.hse.gov.uk/pubns/indg258.pdfThis is a relatively specialised area with lots to consider in order to develop your SSoW, so make sure that you or whoever is going to assess this has the relevant competency level. I dare say other users may provide you with some real examples...
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Rank: Forum user
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Why TIG welding, can you not use MMA, stick welding, therefore removing the inert gas risk. Appreciate you have potentially got more cleaning issue to remove slag and yes there are still the gases from the arc fume to deal with but less sesnsitive to air movement etc so the environment in the space would be improved by air movement.
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Rank: Super forum user
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MMA welding stainless better than TIG ?
Joke surely ?
Massive fume problem in an already confined space. Much larger hex chrome problem coupled with other fume problems.
Heat problem exacerbated.
Vision problems due to much-increased fume generation.
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Rank: Super forum user
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This is a day to day activity in all kinds of industry especially power station/refinery shutdown boiler etc repairs [and that is 'real' confined space working - very very hot, lack of air, almost impossible to move, working upside down in many cases & using mirrors to weld etc - if you haven't done it U may think that am exaggerating but I can assure u that I am not] ] & you may have to use TIG for quality purposes
I would not get to hung up on documents presented by manufacturers as they have [on average] very little site repair experience and those writing such literature constantly put 'riders' in place to steer themselves away from liabilities
Undertake a JSA in a proper step by step way and solve each problem at each stage. One really important aspect is the competence [skill, experience etc] of your trades people and if it looks like the argon gas's is a real problem try breathing apparatus - I have used myself a simple tube with nothing attached to it [it just runs to the outside air from your mouth and nothing else -thats where you are crammed in with no space to turn around] in 'real' confined spaces and took breath through that - you have to have trust in your mates to look after the tube
work out your SSW and PM me noting that your trades people must be involved at every stage
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Rank: Forum user
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Thanks for your replies. I agree TIG is better than other welds due to fume and quality, and my thinking is that risk should be low as long as kit is inspected pre use, leak check completed, pre & contious monitoring of O2 and RPE FPP3 worn for welding process on stainless.
I'm still concerned about escape/retrivel though. The only justification i can see if reducing the risk of injury or heat stress through LOTO, PPE, Cooling area, etc. It just doesn't appear to me that we can rescue a person in this area. Only option i can think of is rescue services destroying the vat by cutting it should it come to a situation were we need to retrieve someone who is unable to do it themselves.
With regards to isolating and locking out pipework feeding the vats, e.g. steam, chemical, liquid product, is it acceptable practice to rely on securing a single valve? E.g. Liquid product enters vat at bottom feedpipe/valve. The one we use to isolate and lock out is an air powered valve at the closest point to the Vat. This is done by closing the valve on the control panel, removing the air line controlling the valve and physically applying a LOTO device to the valve air connector and removed air lines. I have been advised this is secure and the valve cannot fail, but other people say it must be double isolated or isolated and physical break made to the line.
???
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Rank: Super forum user 
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I note the previous responses, and while it is difficult to fully understand the scenario, I wonder whether some form of 'forced ventilation' is as problematical as suggested. It's been a while since I have had any significant involvement with TIG but I am wondering if ventilation is likely to have a significant affect on the rather more localised shroud required for the welding? I accept that there are potential issues of leakage, but would have thought that you could tackle that one separately.
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Rank: Super forum user 
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Low velocity diffuse dilution ventilation would be OK.
The issue comes with air velocity removing the gas shield from the weld zone.
The asphyxiation issue comes with the build up of shielding gas in the vessel.
Argon as we know is heavier than air, thus you need a low level exhaust, you also need a make up situation.
This "could" be from a breathing air "set" at the work location like traditional "BA", though this would not be good considering the other environmental issues.
I would look at an air blown welding mask fed from exterior to the weld location delivering cooler fresh air.
Then I would look at diffuse low velocity make up air at the top of the confined space, with some engineering tricks this could be cooler than ambient thus assisting in cooling the tank environment!
Please remember you need the exhaust though!
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Rank: Super forum user
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Density of Argon is greater than air, maxi,um argon flow rate from the torch (7 lpm). Extraction provided at low level (maybe bottom outlet valve) sufficient to remove at or greater than torch flow rate will prevent accumulation of Argon and O2 deficiency. Top entry and rescue will be a challenge from the description though.
More info would allow provision of definitive ventilation requirements. PS I do not believe that ventilation will affect argon flow rate at the torch.
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Rank: Super forum user
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We had exactly this issue only a few weeks ago. Our solution involved knowing the rate of flow of argon (in our case 8l/m) size of the confined space and caculated time required to create an O2 deficient atmosphere. Divide this by a safety factor of 2, 5, or 10 etc. depending on your other controls / risk and limit the duration of welding in the tank say 10 hour max (assess yourself)
Our additional controls include
P3 mask or preferably battery powered hood (P3) for fume
4" Exhuast vent in bottom of tank - will not affect the shield gas
O2 monitor
Depending on the risk you could include escape sets if O2 monitor alarms or resuce teams etc.
Although the 2 elements of a high risk situation exist (confined space and asphyxiant gas) there should not be a possibility to generate a O2 deficient atmosphere if the controls are followed. Gas should be regulated at the cylinder (in case of line failure / leak) and bottles should be outside of the confined space. Flow rates known, monitors in place, vent (as much as possible) for fumes and argon etc...
Final issue you have is with the heat, but again you will likely need a work rest scheduel which will hopefully coincide with the limits on welding required anyway. Provide cool place of rest, fluids etc. as normal.
Des
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Rank: Guest
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bob youel wrote:This is a day to day activity in all kinds of industry especially power station/refinery shutdown boiler etc repairs [and that is 'real' confined space working - very very hot, lack of air, almost impossible to move, working upside down in many cases & using mirrors to weld etc - if you haven't done it U may think that am exaggerating but I can assure u that I am not] ] & you may have to use TIG for quality purposes
I would not get to hung up on documents presented by manufacturers as they have [on average] very little site repair experience and those writing such literature constantly put 'riders' in place to steer themselves away from liabilities
Undertake a JSA in a proper step by step way and solve each problem at each stage. One really important aspect is the competence [skill, experience etc] of your trades people and if it looks like the argon gas's is a real problem try breathing apparatus - I have used myself a simple tube with nothing attached to it [it just runs to the outside air from your mouth and nothing else -thats where you are crammed in with no space to turn around] in 'real' confined spaces and took breath through that - you have to have trust in your mates to look after the tube
work out your SSW and PM me noting that your trades people must be involved at every stage Nice 1 real world working - this happens on most turnarounds / shutdowns on refinery's! a suitable and sufficient JSA / Risk assessment with the guys involved in the task should do, as long as they are competent for the task in hand
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Rank: Guest
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descarte8 wrote:We had exactly this issue only a few weeks ago. Our solution involved knowing the rate of flow of argon (in our case 8l/m) size of the confined space and caculated time required to create an O2 deficient atmosphere. Divide this by a safety factor of 2, 5, or 10 etc. depending on your other controls / risk and limit the duration of welding in the tank say 10 hour max (assess yourself)
Our additional controls include
P3 mask or preferably battery powered hood (P3) for fume
4" Exhuast vent in bottom of tank - will not affect the shield gas
O2 monitor
Depending on the risk you could include escape sets if O2 monitor alarms or resuce teams etc.
Although the 2 elements of a high risk situation exist (confined space and asphyxiant gas) there should not be a possibility to generate a O2 deficient atmosphere if the controls are followed. Gas should be regulated at the cylinder (in case of line failure / leak) and bottles should be outside of the confined space. Flow rates known, monitors in place, vent (as much as possible) for fumes and argon etc...
Final issue you have is with the heat, but again you will likely need a work rest scheduel which will hopefully coincide with the limits on welding required anyway. Provide cool place of rest, fluids etc. as normal.
Des Spot on Des - We do this type of work on most turnarounds and the controls you have suggested above are correct and sufficient Jk
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Rank: Super forum user
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Also to note HSE information document 288/6 ASPHYXIATION HAZARDS IN WELDING AND ALLIED PROCESSES can be found via a google search
Des
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