Is 24 hour cool down necessary for non exotic welding before MPI

[escapizm]

Is it necessary to let steel sea fasting brackets (S355) fastening containers to a ship’s deck cool down before MPI?.

Would DNV insist on it, it is a DNV registered vessel?

Thanks

 

[denlow60]

yes they can 72 hours or 24 hours

 

[DekDee]

Denlow,
Can you please note where this requirement is stated ?
I would have thought the answer is no.
Regards,
DD

 

[denlow60]

DekDee,

can you show me where it is written that it is no

Regards,

Denlow

 

[escapizm]

I've mobilised many vessels over the last decade and have never came across this requirement, a particular ship yard has said this is a requirement. If it's a mandatory we can pass this in to our client but he will be paying £100k plus / day vessel rate. If it's not the fabricator is trying to have our eyes out!

 

[denlow60]

DekDee,

look in this pdf.

Regards,

 

[DekDee]

Thank you for the information denlow

 

[metengr]

For certain steels delayed NDT is mandated to check for hydrogen cracking in weldments and the base metal heat affected zone.

 

[kingnero]

EN 1090 is not applicable in this case.
I fully agree with the logic behind it, for the reasons metengr explained above.

@ escapizm, you'll have to ask them for a reference.

 

[escapizm]

Thanks all, is this even when proven and tested weld procedures are used for same materials and techniques?

Perhaps we've been cutting corners all these years but I've never come across it before.

 

[DekDee]

escapizm,
I initially thought DNV would refer to EN 1090-2 as posted by denlow so I didn't respond further.
However, having a quiet day at work so thought I would investigate further

DET NORSKE VERITAS

RULES FOR CLASSIFICATION OF
Ships / High Speed, Light Craft and
Naval Surface Craft

PART 2 CHAPTER 3

Fabrication and
Testing of Ships
JULY 2013

SECTION 7 NON DESTRUCTIVE TESTING OF WELDS

For detection of surface imperfections the following methods applies: Visual testing (VT), Magnetic particle testing (MT) and Penetrant testing (PT).

202 For NV 420 grades and higher, final inspection and NDT shall not be carried out before 48 hours after completion unless heat treatment has been carried out.

NV 420 is steel with a minimum yield of 420 mpa and as you are using S355 (minimum yield 355 mpa) the hold period for NDT is not applicable to you,
Regards,
DD

 

[escapizm]

Thanks dekdee you nailed it there! Thanks again.

 

[kingnero]

is this even when proven and tested weld procedures are used for same materials and techniques?

yes, delayed hydrogen cracking can always occur on a later time. Even with correct PQR and WPS

 

[Guest102023]

Define "non exotic"

"If you don't have time to do the job right the first time, when are you going to find time to repair it?"

 

[Aarne66]

Hi escapizm,
I write in connection to thread1083-344803, about the hydraulic synchronizing problem you solved last year (I am asuming everything went reasonably well, at least you had dealt with many contingencies). As it happens, I am working in a different company, which has larger machines that can manufacure the parts for a very large anular cylinder. We are now working with a project for a 1,200 ton force cylinder for R4 mooring chain, the central hole is 400 mm and stroke is 600 mm, equal to the length of each link.
We feel the anular cylinder you initially considered (with longer stroke) can be built and operated reliably, at reasonable cost. You can imagine: the guys in production are OK, the guys in engineering are excited, but the guys in finance are, as usual, skeptic. So, escapizm, I would need to ask if you think there would be demand for such a product, I can only guess it would be used for tensioning of FPSO mooring lines. Would you have been interested in such a product 18 months ago? Would you have rented it for maybe $30,000/month? Do you think other pros in the offshore industry would?
Your views are extremely valuable, and very much appreciated!
Aarne