Welding / Ventilation

Hi All,
I recently came in on Monday to have a look around after not being in for a while.

One of the things I had a look at with my dad was what the best approach would be for fitting the pipe up for welding in weldy grindy in a safe way.
I’d like to request permission (I think it has to be from the board) to do the below so I’ll try and describe what we’re going to do if we get the go ahead.

This is a very rough image but the general idea is to put up some L Brackets and put some bits of cable tray across to support the pipe above the craft area. (there would be more sections than just 2)

It won’t be exactly like this, this isn’t to scale, this is just a rough idea to explain how the bits will be positioned.

Once the pipe gets close to the pink bit of the wall at a later point / later phase
the idea would be to then drill a hole to the right of the pink bit where the weldy area is
then run a dogs leg of flexible pipe from the fixed pipe into the wall

On the other side

again at a later phase
we’d run the spare drain pipe (poo tube) through, the same way we’ve done for the laser
we can then join that to the silver tube with the fan inbetween and a small bit of flexible pipe

At any rate, this is just a request for permission for the initial stage of fastening some brackets and bits of cable tray across to support the pipe as a first thing before anything else.

Also I’m well aware we can’t join into the laser tube, Greg has made it clear it could result in fumes going back into the laser, also I think we want a small chimney on the outside for this second outlet anyway.

Many Thanks

I’d like to reiterate that I’m not convinced this room is best suited for welding at all. You’re wanting to weld in an enclosed space and I’m raising it again that you’re at risk of putting a lot of work into trying to get this small room suitable for welding when in fact there are better areas that require less work. A quick search about welding in an enclosed space brings up numerous issues.

We have other areas that can offer natural ventilation, are less enclosed and lend themselves more naturally to combating the hazards involved with welding. I see a fixation on that room being the welding room, despite the many issues with it being used for that purpose.

Before steaming ahead with the extraction, is there a thorough plan on how that room can become safe to weld in? Any welding area would also need a comprehensive risk assessment - all this will be needed and should be done before spending money and time on an extraction fan and pipe. It would suck if a load of work went into it then an obstacle was found which could have been found sooner.

My standing questions for any welding area are

  • How will this be ventilated? Extraction is not the same as ventilation and so far this seems to just be extraction.
  • How will this be failsafe? If forced ventilation is used, what if it fails? The risks are large enough that we can’t afford to let a failure happen. Are you going to have airflow sensors and contactors to kill power if the fan fails? What will the cost be? Will there be sensors for oxygen and also alarms for dangerous gases? Could better natural ventilation be found? Is it possible for people inside the room to fall unconscious?
  • My understanding is some gases involved with welding are heavier than air whereas others are lighter than air. Both need to be dealt with and risks managed. How does the risk assessment tackle buildups of these gases and the risks they present (such as asphyxiation)?
  • How will this room prevent heavier gasses escaping into the space and potentially down into the nearby lift pit or under the stage? The room and door is not airtight. Will forced ventilation then also be required into the room? How will the ventilation then be managed so air in and air out is balanced?
  • How will lighter gases be removed and prevented from building up? They could seep into nearby units and cause an explosion hazard. How will this be prevented or mitigated?
  • Will this solution be up to scratch if, say, HSE visited?
  • Would a competent person be able to sign off the finished room as safe to use?

The pipe and fan seems like an easy bit to get started with but there’s still a lot of questions that need answering first. Even if you’re determined to stick with this room, permission is granted and you get the work done, there’s the risk that welding won’t be able to happen in that room after all, unless you have a solid plan that is signed off by a competent person giving confidence in everyone that this task is doable. I’ll add, I have no doubt that you’ll be able to do required works, but I do doubt whether the work required for this room is feasible.

I think these key questions have to be answered, shared and looked at by the community and a competent person before modifications are made to the space. I’m not an expert at all by the way, which is why we need a competent person to sign the plans off before you get started and find out there’s a problem.

I’ll further reiterate my suggestion that welding happens elsewhere. Whilst the cable may be expensive to get welding done closer to the fire exit, it would offer natural ventilation, is fail safe inherently, and is less of an enclosed space this reducing overall risk.

Area / Location

I remember we did have a large conversation a few months back of all the pro’s and cons of moving it to a different area, with a large meeting where we all got together and discussed it with large room plans of different options fastened to the wall

I would say the only other area I would consider a possibility personally would be the area next to the snackspace (the area cordoned off via plastic).

  • Currently it has asbestos issues, not sure when or if they’re being sorted out due to covid (removal of the junction box)
  • There’s a lot of mold around there (since it was originally a toilet area) but that could be painted over, I think the drain is sealed now thanks to Jamie.
  • We would need a 3 phase cable bringing in from the board, I’d need to check if the current is right but possibly something similar to this (cost per meter)
  • https://www.essentialsupplies.co.uk/35mm-h07-rubber-5-core-125a-3-phase-rubber-cable.html

In the case of the CNC room I’m very reluctant to consider that area given that it’s currently working / being used by the wood lathe and CNC
(The wood lathe was in use when I came in on Monday)
Also it’s right next to a source of wood dust which isn’t safe for sparks and isn’t any different than the current welding area other than being farther away from power.
And I spent a lot of time and effort painting the ceiling and floor / doing up that area for that purpose.

In the case of the Green Room it’s surrounded by plasterboard and may involve taking out the artificial ceiling.
This in turn could lead to all sorts of issues associated with the asbestos in that area and would make it look a complete mess in the process with exposed brick work etc.
Which is why we ruled that one out at the start.
(we’ve tried covering up exposed brick work with cement, it doesn’t work too well unless you have a lot of cement and a cement mixer so you tend to end up using flammable wood / osb)

I’m not sure of any other areas that could be considered for that purpose that would be easier to setup.
The enclosed space is generally wanted to avoid anything catching fire in terms of sparks jumping about
having breeze block walls with little to no wood in the are was part of the reason that area was chosen
The other issues is the cause of arc-eye where anyone nearby not wearing a mask can get eye damage from looking at the spark.

Electrical Power

In terms of power requirements, In the current welding area we’re right next to a board for hooking into 3 phase.
The best welder we have there is a 2 Phase Tig (It’s wired across 2 seperate phases instead of neutral / live for a higher voltage with a 4 pin plug)
Tig is far far better than Mig for welding and is the one everyone wants to use at the moment.

The only single phase welder I know of we have that works is the small crappy hand held Mig one I brought in which is decades old and seems to leak.
(the small bottle I put on it I think is now empty although it was a long time ago)
We have 2 larger mig’s one of which is 3 phase but needs the instrument transformer swapping out (Stan brought one in but I think it just needs fitting)
The second of which is single phase but I think it might have a different problem to fix (possibly minor).
And there’s also the blue stick welder.

I’m not opposed to using a different area as long as we can get 3 phase in there.


  • For the welding gas’s I’d say we should rule out the use of any explosive type gas’s as a rule such as Oxygen, Propane or Acetylene and stick with inert gas’s such as Argon for reasons of safety.
  • This leads us to using Heavier than air inert gas’s (Argon specifically)
  • For ventilation the general idea was to run the area at negative pressure, although we can put a vent next to the door to allow air to come in from the elevator area as one option.
  • Another option would be to run 2 pipes instead of 1, outlet and inlet the solid pipe looks pretty cheap
  • https://www.ducting-express.co.uk/product/spiral-duct-x-3-meters-long-100-diameter

Monitoring / Fail-safe

Set something up fastened to a large red or green light in the room.
I don’t think cutting the power to the welders would be an option given the large amounts of current involved (unless you got a big ass contactor)

Acetylene torch

Someone did leave an Acetylene torch in there but I’d be tempted to rule that out being used in there anyway
since it’s more a specialised cutting tool, requires a degree of training outside the scope of Hackspace and we have access to hand grinders

If we’re at the stage we want to use that thing then I’d probably look into a plasma cutter instead since that would probably be safer anyway
(Stan brough one in and showed it off, they tend to just use compressed air which is a lot safer)


Watching this discussion from afar … I would only caution you that the electric welders at London hackspace have been the source of some pretty invasive interference, getting into some door control wiring in the area. While our wiring may not be to the highest standard, I would recommend that you keep the welders and their power wiring well away from comms or other sensitive circuitry. Don’t put them just the other side of a wall from your ethernet switches !

Thanks Richard

As I said in telegram i recommend a full risk assessment is done before you start any building work at all the last thing any of us want is to bring something down because its needs a major change etc.

I’d also like to know where exactly the piping is to be run because your diagram is putting it directly through the lighting in the visual arts area and that lighting has been designed specifically and calculated for that area and running a pipe through the middle will add shadows which we don’t want for certain activities. I would also prefer if we could find a way that doesn’t require us to penetrate the plasterboard so not to reduce the fire capacity rating of the board etc but it might not be possible.

like i said in telegram. it is worth while getting the welding team together and coming up with a proper risk assessment for the entire thing including ventilation, routing etc that should provide answers to the questions raised both on here and on telegram.

For the plasterboard issue the idea was to not run it through the pink plasterboard but through the wall directly leading to the welding area (it’s the wall to the right on that image) using some flexible pipe to run a dogs leg from the hole to the fixed pipe.

If the lighting is an issue then we may need to consider instead

  • If we could run it along between the beams in the section closer to the wall with the electrical board on. Or if that would have the same problem with the lighting since it’s still in the craft area.
  • To get some lighter weight flexible pipe instead which wouldn’t need as much support as a cable tray so might allow us to mount it higher up, since I wouldn’t want to mount the solid pipe on bits of string or wire. (given how cheap it is for 10m I’d be tempted to use the flexible stuff anyway)
  • https://www.amazon.co.uk/Aluminium-Flexible-Ventilation-Hydroponic-Accessory/dp/B01H34U8SY/

I’ll try and look at a risk assessment for the docs page when I have time.
I might also try moving the google docs / trello stuff across to there


Thanks for clarifying that richard, I did ask alex that exact question in telegram the other day and was told we were going through the pink plasterboard and not the direct wall next to it. It should be highlighted that that wall has holes in it already at a low level so those are going to need filled to prevent gasses seeping through to visual arts area.

In terms of the pipe run if you can safely run it above the lighting there wont be an issue but i am not sure if the height is there for that but if you can come along one of the beams it might be better we might need to look at a better way of fixing it than cable tray etc so that it can be fixed to the beams without interfering with the lighting etc in the visual arts area.

Don’t take the risk assessment on by yourself get the welding proejct team together even on a chat or jitsi/google meet and do it together it will be easier to do that way.

It’s possible Alex has a different idea, since my proposal above was something we just thought about on Monday when I was discussing it with my Father on the best way to approach it in a safe way

I think if we use flexible piping instead of the rigid stuff all the way down then this might solve the problem of having big heavy supports to hold up the pipe since that stuff is fairly lightweight and might allow it to be near to the beam / in a different place.

For the risk assesment I’ll probably just try and condense as much info from the weldy group as I can into some markdown, then ask for input to add / update anything there.
Ideally we also need to get a common consensus on the approach to take as well as the risk assessment.

We’ve had an email from a member regarding the welding setup below is copy and paste from the email


As far as I am aware there hasn’t been a public request for advice or guidance on this topic.

IIRC I think Brittan used to work as a HVAC engineer so he might have some experience that could help with some aspects of this job.

Otherwise has anybody made any formal/informal requests for advice/help from welding companies/technical colleges.

I’d recommend reaching out and asking for two reasons.

  1. Doesn’t cost anything, worst they can do is ignore us
  2. Possibility of generating interest from these people that could help the space.


We currently have 200mm Steel Ducting, ~3m x3 & ~2.5m x1.

Comments have been made about using a ‘poo’ pipe to cover the remaining distance if the quantity above isn’t enough. I believe this is a bad idea as we need to make sure the pipe is sealed all the way to the extraction point (outside), taping on the PVC pipe at the end would probably work, but considering the function i’d advise against it and ask that a proper job is done.

Buying extra pipe is what I’d recommend, it’s a bit expensive at £24.33 for 3m, https://www.ducting-express.co.uk/product/ducting-fittings/spiral-ducting/spiral-duct-x-3-meters-long-200-diameter

We would also need to order couplings and fittings to suit the pipe to ensure that it is correctly installed.

Reading the ducting express’s website they also offer flexible piping, it maybe worth while asking about this option as it might be better for us over rigid pipe.


The proposed route has multiple obstacles that need to be considered. from walls, electrical conduit/trunking, lights, water pipes & sprinklers.

The proposed idea at the moment is to support the pipe using the cable trays. I was under the impression that they were to be used for the network cabling (Probably need to check with Adam rules on how important that is). Additionally the pipe is heavy and I’d like to see some calculations proving the proposed supporting method is suitable. The span between the I beams is ~2.6m. The thin wire cable trunking isn’t intended for being used as a pipe support and may flex/bend under load.

There are two options I would suggest.

  1. Look at the possibility of drilling anchor bolts into the brick arches. This allows us to mount the pipe higher in the arch avoiding most of the obstacles.

  2. Route the pipe along the I beam that is between Visual Arts and the main area. Have the pipe run on the main area side as it doesn’t have any electrical conduit along it. I’ve attached a couple pictures to show what I mean.

This route however would require additional fitting to accommodate the bends. By having the pipework closer to the I beam the downward support load would be minimised (F=M*D).

@Board There are 45° bends available for 200mm ducting, and it can be purchased in pvc/plastic and metallic formats. This would add a slope to the end of the run, nearest the welding area down from the beam, into a 90° bend beneath the beam. It is preferable to have as few 90° bends as possible, due to restriction in flow.

Secondly, for every unit of air extracted, you need to be able to provide a minimum of a single unit of air input/replacement, or more, at least equal exchange, or as per the latter positive pressure. Operating in a negative pressure environment is ill advised, as you will lower the percentage content of air in the workspace, effectively diluting it; in a closed room, unsupervised, you would have potential risk of reaching a threshold resulting in mild asphyxiation, and/or blacking out, the space’s insurance would be null and void under such a situation, and ultimately, who would be responsible?

In a negative pressure environment, unless a positive demand breathing air supply mask was in use by the operator, officially trained, then the HSE would never approve the use of such an environment, and would labour heavily over an investigation should an accident occur, which would ultimately require reporting.

I’m aware I haven’t contributed a great deal to the group as of yet, and my apologies if I come across the wrong way, no offence is intended, however, I have spent the majority of the last 20 years complying and working with the HSE directly in a multitude of environments from engineering areas, to factory production environments, and small business workshops sized areas, across a broad spectrum of service delivery, including but not limited to electrical, air supply, and chemical transfer.

As said, it would be good to get everything down on paper, drawn out, wiring diagrams, plans, proposals, what the actual area is going to be used for, risks we have assessed, things we’re not sure of, you don’t look stupid for asking simple questions, better to ask, than to not, and subsequently get in trouble for it, we’re classed as a business after all I believe, and the HSE can be extremely, and I mean extremely helpful if you ask for their advice, and tell them if you aren’t sure of something, they actually like helping people do things right. My father was a senior HSE adviser for some 10 years towards the end of his career with AstraZeneca.

Again, as above, local providers of services may be more than willing to help as well, BOC based in Worsley are a good source of support, and could supply welding gases at discount with delivery/collection, and again as per other’s comments, local businesses and colleges.

Just my 2p,


Just a thought but is there no way to route the pipe under the stage and popup where the vent pipe for laser cutter is and follow it out?

We’ve come up with another possible idea on telegram

Which is to use the area mentioned before, the one currently cordoned off via plastic sheeting next to snackspace. Since that area has a wall facing the outside.
For that to work though

  1. There’s a live electrical box with some asbestos in that needs to be boxed off. I’d like to know if this is something I’d be allowed to do or if there’s any special requirements as far as hackspace rules / health safety etc

  2. Do we know the feasibility of running 3 phase into that area? in terms of cost etc

  3. The only other outstanding thing would be building another wall with a door to split the area I think which would be a lot easier than trying to run pipes everywhere.


1 Like

If it’s only a small electrical junction box, then it may be economical, more so than it seems, to get someone in to remove the asbestos and make it safe, then you would potentially have an electrical supply point to use for the area?
I can’t see the cost being astronomical, and more than likely something within reach of the space’s funds from Covid, without making a massive dent, and longer term guaranteeing the safety of the space, and maximising the use of the space available?


The asbestos box is something that Ben and Adam have already looked into quite a bit. I think one of the problems is that it’s live and there’s no way to cut the power to it because of the way it’s wired in.
I think that’s why they’ve decided to just box it off rather than remove it.

I am enjoying this discussion as an interested party, but what are the procedures for producing a risk assessment and plans that are acceptable to the board? Do we have a template to work to, for example?

I agree with the idea of asking for external help. My (former) welding tutor does offer some for of training and H+S assessment service in a freelance capacity. I’m happy to ask him.

It feels like the board has an idea of acceptable project governance for large and potentially dangerous workstreams like this, but isn’t sharing a clear picture of what that is.

A risk assessment is something we’re going to be looking into (instead of the board it’s the people associated with the weldy team that need to be initially looking at that)
But we also need to establish the location since that will have a big impact on things including the risk assessment.

There was some recent discussion on telegram and the proposition of moving the welding area to the front of the building possibly where the existing snackspace is at the moment or to the right of it or left (to the left is the green room area which has some other issues)
since that would provide better access to an emergency exit (in the center area) and would be next to a wall to the outside. However we also need to make provision for the kitchen as part of that.

One of the things I’d like to know as a starting point is if there would be any issues with me boxing off the electric box myself as that could act as a show stopper for that area.

ah OK. I still feels (to me) a bit like walking through fog. How does anybody know the procedures for choosing the room? Who decides?

There’s a few of us who stated the ball rolling on getting the welding room up and running – perhaps precociously – but now the board (not without reason) are saying, “Hang on, you’ve done this and this and this wrong.”

Now we’re going away and having another crack, but with no specific framework to work within. So how do we avoid being in this same situation in a month’s time? It’s fine being told to go away and come up with a plan, but there’s a tonne of knowledge about the infrastructure and specificities of the space and the organisation that I just don’t have, and I don’t know how we can come up with a plan that’s likely to be approved without that knowledge.

Hi Mike

First of all there hasn’t been any official board feedback on this (its why I’ve been careful to post messages from me under my account and not the board account). I did mention on telegram to alex when this came up a week or so ago that (copy and paste from telegram)

“These things do come out of the woodwork but it should be part of your planning and its come up now because you’ve been posting about it in here but I could of missed it and apologies if I have but I havent seen anything come in to the board email with these are our plans for the area and this is what we want to do one of the core rules at the moment for the space due to the covid secure guidance is that no major work should be done on the space without board approval but even without that its something that has an impact on the H&S of the space and members so you should running your plans past the board directly don’t rely on one of us to be in a chat on telegram about it because thats not the best approach) your talking about erecting something that will take gases out of the space but even its not just air flow we need to know its safe in terms of air flow precautions, but also what steps you are taking to make sure it doesnt fall down and hit someone on the head. Risk assessments aren’t fun or pretty but for something this serious they are needed. My approach in general is just lets gets something done but in some cases we can’t just go ahead and do it… I am recommending you do a risk assessment before you do any work in terms of hanging stuff as I don’t want to have to say to you this needs to come down because its not safe. there no fun for me in that. I want to see a welding area setup but I want to make sure we don’t kill anyone too”.

The board wont decide the area its not a board thing to do it needs to be a members consensus its up to the metalworking/welding team to look at the options in the space that could be used for welding and decide the best one and share the idea on the forum and/or a members meeting (preferably both) then if the general consensus is we should move forward with it then thats fine and as with any new dangerous tool a risk assessment and induction plan is needed (which alex would know as he had to sort it for the lathe).

We dont have a procedure for large scale changes to the space, maybe we should but we try to keep a flexible approach and really the only time issues to the space changes arise is when there is H&S aspects to consider.

The best approach going forward would be those interested in welding get together and come up with a solid plan that can be shared on here for feedback (a bit like what happened when people wanted to make changes to the space in December last year) assess the risks / assess the routes for ventiliation etc and then take it to a members meeting where a final decision can be made once thats occured the risk assessment needs to go to the board (this can be done after the work has been done but I advise to do it prior so that should any changes be needed its easier to do at that point and not when there is ventiliation etc up).

To summarise the events so far.

I think the initial assumption was that we could run a single pipe from existing weldy area to the outside then just run at negative pressure (sucking up the fumes and argon) which would have been nice and simple.

But as Omniatus as highlighted it probably wouldn’t be that simple from a HSE point of view in that bringing in air in (possibily a second pipe) would also be needed unless we’re allowed to suck it in from the elevator area via a vent or something or another fan (I don’t know about that myself, that’s another question)

This also then leads to the conversation over how we get pipes across, Rossy indicated he didn’t want the lights to be interfered with in the craft area / any shadows which meant running pipes in non direct route along the side of the beams.

  1. Running pipes at 90 degrees is apparently a bad thing for air flow
  2. If you use flexible pipes then you need more brackets to stop it from sagging
  3. If you use stiff pipes (like we have in the elevator area) then you can’t just use wires, they’d need to be brackets to hold them up and stop them falling on someone’s head
    (this isn’t an issue btw I’m sure we could over engineer something very safe, it’s just a case of figuring out the path and number of pipes / type of pipe etc)

If we move weldy to the front of the building then it solves a lot of these problems

  1. minimum pipes to the hood from the outside
  2. it might be seen as more safe since you’ve got a second exit that we don’t normally use available in an emergency.
  3. It might be easier to get long materials in / out through that second door.

CNC room I feel is out of the running because it’s next to a source of wood dust (which is bad when you have sparks) and is already in use by the CNC / wood lathe.

Connor mentioned the green room several times, but in my opinion it’s the worse possible place for it since you’d have to strip all the plasterboard out and the artificial ceiling with a ton of exposed brickwork, to then make it not look like a bomb had gone off cement it all up with a cement mixer to make it look reasonable etc which would be a ton of work. Add to that, that there are not many people around at the moment due to covid etc

For the front of the building option this would then leave 2 locations available

  1. existing snackspace area (middle)
  2. right of the snackspace area (right) - same area with plastic strips currently cordoned off.

With these areas there’s no plasterboard to strip out and it painting the ceiling or floor would be simple.
Part of the consideration is that there’s also going to be a kitchen in that area I think sort of next to the snackspace.
Given that the middle zone (where the snackspace is at the moment) is right next to a door outside I suspect the middle area would be preferable.
But to do that we’d need to move the snackspace to the right and make allowances for the kitchen area.

Existing Weldy Option

Ideally we’d need advise from someone who knows something about HSE (maybe Omniatus can advise)

  1. Do we need a pipe bringing air in from the outside as well as taking it out?
  2. could we just stick a vent on the side of the wall to let air in from other parts of the hackspace?
  3. does only having one door exit violate any HSE rules?
  4. I’m assuming we’d need monitoring on the air flow?
  5. Is there anything else that could be thought of?

Sensors for monitoring gass’s would be a must but I’m not sure which ones off hand personally just yet.

Snackspace / Right of Snackspace areas

The very first thing should be the walling off of the live asbestos electrical box before we even think of moving things around or consider the specific location.
I suspect me and my dad shouldn’t have a problem doing that (he’s done a lot of work in factories with industrial wiring and is very good with wooden walls)

  1. Is there board approval for this?
  2. Are there any special requirements you’d like us to take before doing this?
    (I’ll be wearing P3 masks and avoid touching the box)

This is something that needs to happen anyway regardless of weldy.

Risk Assesment

My plan is to google some existing risk assesments from maybe other hackspaces or places online and try and piece together something that way.
Although the location will have a big part to play in it I suspect due to the number of exits and ventilation.

Many Thanks

1 Like

As far as a welding team I don’t think there really is one in the strictest sense of the word.
Just more a bunch of people who know a bit here and there on the weldy telegram group

There’s Alex who seems very interested in weldy but it currently under Quarantine
There’s myself who doesn’t need to do any welding at the moment but I’m just looking for a direct list of things to do to get things setup.
There’s Stan but he’s not been in the space I think for a while
There’s Mike who brought in the Tig welder (I think he was around the last time I was in)

I’m not sure who’s been around I suspect not many due to covid.
I did try raising the front of the building option in the telegram weldy group but I think only Bob replied to it, so getting a conversation going is difficult.

Since Alex isn’t around at the moment I’m just to narrow down the options of what is practical / realistic (to avoid too much in the way of bike shedding)
If we can narrow things down as much as possible then it reduces the complexity as far as a welding team making a final decision.