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Technical Discussions
jason hewett
jason hewett
03:30 Jun-19-2008
lamination vs stringer

My client has specs for welding close to laminations but none in regards to stringers. I'm currently inspecting 12" x 6.4mm late 1950s pipe that is full of inclusions/stringers. It's not much of an issue when doing a tie in on dead pipe, but welding line stoppers (fillet welds) onto live pipe with stringers present is making me nervous. Should I have cause for concern?

Cheers

Jason


 
 Reply 
 
Ryan Burns
Ryan Burns
06:24 Jun-20-2008
Re: lamination vs stringer
Hi Jason,

My opinion is that it would depend on the depth of the stringers. What is the product and pressure in the line? If you are finding multiple indications at varying depths in the area of the anchor welds, then yes, I'd be concerned. Is there any chance you may be seeing HIC (Hydrogen Induced Cracking)? Have you done shearwave to find any step cracks? I'd also suggest using a delay line transducer to ensure near surface indications are not missed, as well as black on white MT to ensure there is no SCC present.

Good luck,

Ryan

----------- Start Original Message -----------
: My client has specs for welding close to laminations but none in regards to stringers. I'm currently inspecting 12" x 6.4mm late 1950s pipe that is full of inclusions/stringers. It's not much of an issue when doing a tie in on dead pipe, but welding line stoppers (fillet welds) onto live pipe with stringers present is making me nervous. Should I have cause for concern?
: Cheers
: Jason
------------ End Original Message ------------




 
 Reply 
 
David Hermanutz
Consultant,
Hbndt.com, China, Joined Jul 2012, 85

David Hermanutz

Consultant,
Hbndt.com,
China,
Joined Jul 2012
85
01:55 Aug-22-2008
Re: lamination vs stringer
Hi Jason,

Hot Taps on live lines need to have good material, I have rejected pipe three times in a row for stringers, Like you , I also had no direction on Laminations but felt that it was neccessary to go with caution.

If the pipe is excessively "dirty" it may also have unknown material properties such as High Carbon that could lead to cracking and failure of the hot-tap procedure. Old pipe manufacturing had a ridiculously low amount of Quality Assurance performed, and may not be fit for the service it has been operating under.

Be safe!

David

Regards,

David

----------- Start Original Message -----------
: Hi Jason,
: My opinion is that it would depend on the depth of the stringers. What is the product and pressure in the line? If you are finding multiple indications at varying depths in the area of the anchor welds, then yes, I'd be concerned. Is there any chance you may be seeing HIC (Hydrogen Induced Cracking)? Have you done shearwave to find any step cracks? I'd also suggestusing a delay line transducer to ensure near surface indications are not missed, as well as black on white MT to ensure there is no SCC present.
: Good luck,
: Ryan
: : My client has specs for welding close to laminations but none in regards to stringers. I'm currently inspecting 12" x 6.4mm late 1950s pipe that is full of inclusions/stringers. It's not much of an issue when doing a tie in on dead pipe, but welding line stoppers (fillet welds) onto live pipe with stringers present is making me nervous. Should I have cause for concern?
: : Cheers
: : Jason
------------ End Original Message ------------




 
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