Minimum Distance between longitudinal welds of adjoining sec

By Nanjing Date 09-29-2008 06:30

This can be accepted if agreed between the Owner and the Fabricator.

By kylm kochunny Date 09-29-2008 12:37

Yes, you are correct.
But is there a technical justification is there to provide? e.g. Any calculation or reference to proove the integrity.

By Nanjing Date 09-29-2008 20:43

Code does not address this.

By kylm kochunny Date 10-06-2008 05:04

Dear Nanjing,
You are very correct.
For this reason only I was looking for a valid justification, so that we can obtain a waiver from the client.
Thanks for the effort
Regards

By Noel Tan (**)

Date 09-30-2008 01:32

Kylm kochunny,

46" pipe with long. seam staggered 35degrees, the length between 2 longitudinal seams is about 360mm.
The AWS D1.1 code book specified "shall be" 90degrees means a mandatory requirement if client approval is not obtained .
(of course more accurately the code book should specified also a minimum staggered length that 2 longitudinal welds will no longer affect each other)
but with staggered length of 360mm, i think you got a chance to get the approval from your client.

* For offshore pipeline construction according to DNV standard, the staggered length is required minimum 50mm only.
Since this is for different application, so i do not think you can use it as a reference.

Regards,
Noel Tan

By kylm kochunny Date 10-06-2008 05:11

Dear Noel Tan,
Thanks for the suggestion.
We are in the process of getting a waiver from client.
We can not apply a pipeline standard here since the design for such items are based on hoop stress and here it is based on load + other criteria such cyclic, seismic etc...
Best Regards