Wedg1e
They call me Mr. Bodge-angles
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- 7,756
- Location
- Teesside, England
Some of you will have seen my thread in the Plasma Cutters forum about repairing a bodged pipeline, well we started work this week, here's a few pics...
The plan is to chop off the previously-badly-welded flared ends and remove the clamping rings which are in cadmium-plated mild steel, not stainless like they should have been. We thought an air-powered hacksaw might do it, so we hired one to try.
It worked, so we lugged it down into the culvert where 80 of these joints need to be cut out. There are a further 100 or so topside as well. Some will be rewelded with new flares and stainless clamp rings, and this time we'll see to it that the welders aim for full penetration and use s/s rather than mild filler
The majority of the joints will be remade using TK rubber couplings as used on HM warships - we can pressure test to over 10 Bar, the line will never see that in use as it just carries seawater to a fire control installation.
We do have the slight draback that whenever the tide comes, in, part of the culvert floods... as you can see form the damp walls and corrosion.
The sparkly drops on the ceiling are condensation.
Each saw-cut takes about 15 minutes plus setup time. We think if we're careful we can get 16 cuts from a blade (first one managed 4) - the teeth get stripped towards the end of the blade, maybe due to the extra leverage at that length.
As a comparison I took my 30A plasma cutter along: it will do a full circumference on the 10" line in under a minute
however we'd need to make a clamp-on guide to get the edge straight, then the raggy bits would need dressing whereas the saw-cut merely needs tickling with a file - so there's not much in it. We can hire a fleet of saws for the weekly price of a plasma cutter although the saw blades at £15 a pop might eat into the budget somewhat!
Noise-wise the saw is deafening even in the fab shop: in the culvert it was criminal. The boss reckons we can get four going at the same time, not sure how we'd hear the gas alarms if they went off though!
The air hiss is the only noise issue with the plasma. I think the plan is tending towards using saws in the culvert and plasma for the topside cuts, if only to speed up the topside work and let the guys crack on while two of us live in the culvert for a fortnight
We'll probably end up with eyes like a hobbit...
The plan is to chop off the previously-badly-welded flared ends and remove the clamping rings which are in cadmium-plated mild steel, not stainless like they should have been. We thought an air-powered hacksaw might do it, so we hired one to try.
It worked, so we lugged it down into the culvert where 80 of these joints need to be cut out. There are a further 100 or so topside as well. Some will be rewelded with new flares and stainless clamp rings, and this time we'll see to it that the welders aim for full penetration and use s/s rather than mild filler
The majority of the joints will be remade using TK rubber couplings as used on HM warships - we can pressure test to over 10 Bar, the line will never see that in use as it just carries seawater to a fire control installation.
We do have the slight draback that whenever the tide comes, in, part of the culvert floods... as you can see form the damp walls and corrosion.
The sparkly drops on the ceiling are condensation.
Each saw-cut takes about 15 minutes plus setup time. We think if we're careful we can get 16 cuts from a blade (first one managed 4) - the teeth get stripped towards the end of the blade, maybe due to the extra leverage at that length.
As a comparison I took my 30A plasma cutter along: it will do a full circumference on the 10" line in under a minute
however we'd need to make a clamp-on guide to get the edge straight, then the raggy bits would need dressing whereas the saw-cut merely needs tickling with a file - so there's not much in it. We can hire a fleet of saws for the weekly price of a plasma cutter although the saw blades at £15 a pop might eat into the budget somewhat!Noise-wise the saw is deafening even in the fab shop: in the culvert it was criminal. The boss reckons we can get four going at the same time, not sure how we'd hear the gas alarms if they went off though!
The air hiss is the only noise issue with the plasma. I think the plan is tending towards using saws in the culvert and plasma for the topside cuts, if only to speed up the topside work and let the guys crack on while two of us live in the culvert for a fortnight
We'll probably end up with eyes like a hobbit...
getting paid too much and likes hard work 
