For pro/commercial welders

[WALM]

been approached to do a welding job on the door of a septic pit... it is in the middle of a courtyard of a large residential building, the doors are galvanised steel frame with paving slabs on top. Double doors that open upwards on a hinge one side on each door. They both have a latch that falls into place to hold the door open, one latch has broken off the frame (not the door)

Now... the weld is easy - better if it wasn't galv, but hey ho. It's everything else.

Firstly I'm pretty sure that even with risk asseesments and method statements my insurance wouldn't cover me.

Secondly and probably the most prominent point is methane as the septic tank is live. Presumably if any kind of spark were to venture into the tank she will go up?? (From an HSE point of view)

Thirdly if I cover the tank (somehow)then surely it would be more dangerous.

And lastly I don't really want to fall into the bugger.

I'm sure the answer is don't touch the job. But I like a challenge when it comes to HSE and doing things right. Their tank people won't touch it until the latch is fixed. So I think I might be their only option.

 

[wookie]

You might like a challenge but it could all go very badly wrong with the least worse option being you end up falling in the tank.

There was an methane explosion at a pumping station near where I used to live https://en.wikipedia.org/wiki/Abbeystead_disaster several people were killed, I remember it being on the local news as I was only a young 'un back then, personally I'd be running from the job... fast !

 

[colnerov]

Hi, I believe there is another concern in that you need to have the necessary injections to work on equipment that contains bodily fluids, particularly waste ones. So some thing else to think about maybe @Parm or is it @skotl can confirm. Sorry I can't remember which one is the H&S guru, mind has gone a blank.

Colin

 

[Rig Pig]

Drill and bolt a replacement on? We tend to use welding as a last resort offshore.

 

[wyn]

I'd have thought you're going to need barriers, gas monitoring equipment, possibly breathing apparatus and training incase things get dodgy.
Harnesses, another bloke or two to drag you away if things go wrong. Equipment to vent the area under the doors.

 

[addjunkie]

Drill and bolt a replacement on? We tend to use welding as a last resort offshore.

Im in the same place. Id even be weary of bolting due to the potential spark from the drill

 

[colnerov]

Hi, Yes of course it's Parm, my apologies to skotl for any offence.

Colin

 

[bigegg]

"large RESIDENTIAL building"
+ potential explosion?

Run away. Don't walk - RUN.

 

[Spark plug]

Would it not be possible to remove the hatch, I imagine this would require lifting equipment. Make the repair away from the pit then replace?

 

[God mode restorations]

I use to work on anglia water sewage pumping stations ect. Entering a erea where methane is present is called a dsear and you have to remove everything electrical. Phones ect...I would definitely be walking away from this job. Admit it's been a few years since I left but the health and safety around these places is crazy.but rightly so.

 

[WALM]

Thank you all for such great response, I think lifting the entire thing out could be an option. But to do this safely would I think require "trained" people. Bolt idea could work, but yes weary of drill sparks, maybe a long day with a manual drill??!!! This is a picture of the non broken latch on one door. The piece of angle with the bolt on has just come off the frame, so if I can stop myself falling in then possibly just drill a hole by hand???

 

[WALM]

Hahaha

 

[WorkshopChris]

Fabricate something to bolt on. Lots of ventilation and a air drill, no spark risk from the brushes.

 

[bigegg]

Fabricate something to bolt on. Lots of ventilation and a air drill, no spark risk from the brushes.

Fabricate something to clamp on - no drilling at all then.

 

[addjunkie]

Hard scafold barriers around it, and wear a restraint harness when working so it is impossible to fall in, you will want some kind of vapour mask not sure on the type. Also as a minimum a standby man.

Obviously lifting the lid...itll be bloody heavey. Then once you lift it, id board over the hole. Warning signs etc.

 

[WALM]

Air drill

Great shout.

Clamping also good, just not sure quite how.

 

[WALM]

Hard scafold barriers around it, and wear a restraint harness when working so it is impossible to fall in, you will want some kind of vapour mask not sure on the type. Also as a minimum a standby man.

Obviously lifting the lid...itll be bloody heavey. Then once you lift it, id board over the hole. Warning signs etc.

That sounds like a good plan. Thanks

Anyone who mentioned running away still have any reservations?

I will have a look through working with septic tanks HSE, re. Injections etc...

 

[wyn]

I'd hire a gas monitor to make sure there is no hydrogen sulphide or flammable gasses.
If there are gasses use forced ventilation to reduce it till it's acceptable, then sparks/heat shouldn't be a problem.

 

[bigegg]

I have a new (better) plan.
Get someone else to quote, then add 25% management fee.
Get them to do the work.

 

[addjunkie]

You could use a haz mat type vapour supression type foam on the surface, force ventile first. The foam will be bloody expensive though.

When you hire your gas detector it will need to be something like a crowcon triple + that measures oxygen, methane, and h2s