Testing the welding integrity of an overplated boat

[DHutch]

As said, a pressure test while generally very simple and clear test has limitations. It only tests for leaks not weld integrity, and would not work if the original hull leaked at all before the plating.

 

30 psi is far higher than needed and could cause issues and or be dangerous, but as said a much lower test pressure would work fine. 

 

Emily Anne is 28years old and fully insured but we do paint the hull well, and have to have a five yearly hull inspection. 

 

Daniel

[MtB]

7 hours ago, mark99 said:

butt welding.

<snigger>

 

[mark99]

Here is some fillet welding we done today 25 foot from a canal (so on topic)    The canal is behind the green sheet.

 

PS that is a live gas pipe with 100 psi in it we are welding the tee onto. The welders requisite skills are second to none and strictly tested. You don't let any old welder loose on this stuff.

 

You can see the MPI test residue.

 

                          

 

 

 

 

Edited November 26, 2018 by mark99

[NB Esk]

28 minutes ago, mark99 said:

Here is some fillet welding we done today 25 foot from a canal (so on topic)    The canal is behind the green sheet.

 

PS that is a live gas pipe with 100 psi in it we are welding the tee onto. The welders requisite skills are second to none and strictly tested. You don't let any old welder loose on this stuff.

 

You can see the MPI test residue.

 

                          

 

 

 

 

I wish I could zoom in without losing resolution but from what I can see I'm thinking they're using 6010 electrodes?

 

 

[ditchcrawler]

2 hours ago, mark99 said:

Here is some fillet welding we done today 25 foot from a canal (so on topic)    The canal is behind the green sheet.

 

PS that is a live gas pipe with 100 psi in it we are welding the tee onto. The welders requisite skills are second to none and strictly tested. You don't let any old welder loose on this stuff.

 

You can see the MPI test residue.

 

                          

 

 

 

 

Hot taps, we use to have to drop the pressure to do that as the metal would lose its strength with the heat from welding.

[mark99]

8 hours ago, ditchcrawler said:

Hot taps, we use to have to drop the pressure to do that as the metal would lose its strength with the heat from welding.

 

We don't need to drop pressure as the internal pressure above in the live parent pipe whilst large is not huge (e.g. offshore pressures are circa *10 the above) compared the the parent steel's SMYS. NB - we scraped the parent steel  and lab tested it before confirming the weld procedure.

 

 

Edited November 27, 2018 by mark99

[blackrose]

How does dye penetration testing work on structures where you can't see both sides? I've only used it on seals and joints where both sides are visible and you can see if any low viscosity dye has been drawn through by capillary action. Also used it on transparent or translucent materials where the dye is visible. I can understand how boat builders could paint or spray dye onto a weld and check for any traces on the other side, but I can't work out what you would look for if you applied penetrant dye to overplating?

[mark99]

2 hours ago, blackrose said:

How does dye penetration testing work on structures where you can't see both sides? I've only used it on seals and joints where both sides are visible and you can see if any low viscosity dye has been drawn through by capillary action. Also used it on transparent or translucent materials where the dye is visible. I can understand how boat builders could paint or spray dye onto a weld and check for any traces on the other side, but I can't work out what you would look for if you applied penetrant dye to overplating?

 

At the industrial end of the scale.

 

 

Dye is limited to surface as you say. Over plating will be via a fillet weld not a true full penetration. Generally fillet welds will be tested by visual inspection standing observing by third party if needed or by welder self testing visual, and/or dye or MPI inspection. Or none of that just a simple pressure test (eg pipe will be subject to such a low hoop stress compared to steel grade/SMYS it's not needing great strenth just to hold the internal fluid).

 

Weld with a true bead (the weld bead penetrating both prepped edges to co-join uniformly and fully the two component parts) and the bead is where core strength is will need more integrity check generally (eg radiograpahy) NDT to check full depth of weld (incl bead) plus visual. i.e butt welding. The two pieces are set up with an engineered gap and angle (pre detailed via weld procedure)  to allow the root to burn into both faces form a strong bead.

 

In both cases the welds will be to a procedure pre-agreed and signed off by a qualified weld engineer. And if required the first couple of welds will be cut out, sectioned and sent to an aproved lab for mechanical testing (charpy, tensile, etch). Although the lab "mechanical" results are a test of the procedure not the welder. The visual and NDT (by qualified third party inspector) will normally throw up whether the welder is good enough.

 

All imo - I'm not expert although we weld fillets and butts via contractors every day @ work.

Edited November 29, 2018 by mark99

[Tacet]

On 26/11/2018 at 20:17, mark99 said:

Here is some fillet welding we done today 25 foot from a canal (so on topic)    The canal is behind the green sheet.

 

PS that is a live gas pipe with 100 psi in it we are welding the tee onto. The welders requisite skills are second to none and strictly tested. You don't let any old welder loose on this stuff.

 

You can see the MPI test residue.                

 

 

 

 

 

 

At which stage of the process is the wallpaper pasting table deployed?

 

 

[Alan de Enfield]

11 minutes ago, Tacet said:

 

At which stage of the process is the wallpaper pasting table deployed?

 

 

When they come to 'paper over the cracks'  ?

[MtB]

2 minutes ago, Tacet said:

 

At which stage of the process is the wallpaper pasting table deployed?

 

 

 

I have to say a related thought crossed my mind too. For such controlled quality welding I'd have expected a more comfortable working environment to have been arranged for the welders. Loose gravel is a surprisingly hostile and uncomfortable surface to be kneeling on, hence the pasting table I reckon. And its an awful surface to put hand tools, bits and pieces etc down on without losing them.

 

Were I the welder I'd have been demanding the hole be dug 2 ft deeper and plywood laid on top of the gravel, so a nice comfortable low stool could be sat upon whilst welding instead of grovelling about on knees. A task demanding such a high degree of manual skill and dexterity needs as comfortable a working environment as poss for really good work to be done.

 

And my welding qualifications entitling me to comment are: Zilch...

[mark99]

Welders and weld inspector have last say re excavation. You have to work within site constraints. There is a canal behind that sheet.

 

[ditchcrawler]

1 hour ago, mark99 said:

Welders and weld inspector have last say re excavation. You have to work within site constraints. There is a canal behind that sheet.

 

And welders can have very mixed reaction to having a weld knocked back or even the fact you are testing there work.

[WotEver]

 While I have you Welders here... would this be a decent buy for a welding noob who would probably only use it a couple of times a year on relatively light stuff? And would I be best off with the gas conversion? 

 

Thanks, Tony

https://www.machinemart.co.uk/p/010110125/

[mark99]

38 minutes ago, ditchcrawler said:

And welders can have very mixed reaction to having a weld knocked back or even the fact you are testing there work.

It's never a good one!

 

Ours is 100% inspection and ndt. Xraying butts and mpi others.

[MtB]

6 minutes ago, mark99 said:

It's never a good one!

 

Ours is 100% inspection and ndt. Xraying butts and mpi others.

 

I'm curious now. What happens if a weld on one of those live taps fails inspection? Does the pipeline have to be evacuated, the section cut completely out and a new bit welded in?

 

Or do you abandon it and weld in another one six feet along?

 

[mark99]

7 minutes ago, Mike the Boilerman said:

 

I'm curious now. What happens if a weld on one of those live taps fails inspection? Does the pipeline have to be evacuated, the section cut completely out and a new bit welded in?

Welded and sentenced. Once sentanced as ok, only then is it drilled through valve. So unless you burn through pipe you have no leak path.

 

If fails sentance the weld may be repaired, dressed, epoxy clamped or scheduled for cut out. 

 

Thats why you need good welders and procedure.

 

Before the hot tap we untrasonic the pipe to check for laminations in parent pipe also scrape off a bit of the steel on parent and lab test it for quality and weld compatability. We could fill a small car with the paperwork , planning docs and licences needed for this work.

Edited November 29, 2018 by mark99