Golden weld in pressure vessel columns 1

[waliq]

Hi all,

I have heard about golden welds in gas pipelines. I know little about these welds in that they need to be performed by highly qualified welders, cannot be hydro statically tested and need more than one NDT methods to compensate for the hydrotest not performed.

However, I want to know if the same can be done for tall columns (pressure vessels)?
Some columns, that are like 60 m tall may not be transported as a complete unit and may require them to be transported in two units that can then be joined at site via a golden weld.
In this case, will the two units transported be shop tested individually? If yes, then how?
And, does ASME code give exemption of hydrotest anywhere in ASME Sec VIII, Div.1 apart from ASME B31.4?

 

[Dhurjati Sen]

Dear waliq,

Are you talking about propylene columns?

They are often welded at site, (due to transportation issues) though hydro-tested in the horizontal position after taking into account the vertical head.

The concept of golden joints is yet to come for pressure vessels.

Regards.

P.S. For piping, the golden joint concept has come when new piping is connected to the existing one. So the tie-in joint becomes golden. In case of complete new piping, it would be very poor engineering practice to leave few joints out of hydro-test.


DHURJATI SEN

https://www.nace.org/people/dhurjatisen

 

[Inspectengr]

Have u tested rest of the vessel with installing or welding temporary blinds. If yes.


Then only one field joint is not tested. Which should be enhanced in ndt. RT or UT 100%.


Its a normal practice.

 

[marty007]

I have seen this done in two ways:

[ol 1]
[li]Fabricate the complete column in the shop at full length (60m for example). Perform the hydrotest on the complete unit and complete all ASME documentation (stamping / U-1 forms / etc...). Then cut the vessel in half and ship to site. Now when the weld is performed joining the vessel back together, the work is deemed a repair and is performed per NBIC. NBIC states that it should be hydrotested unless it is not practical. If it's not practical (refractory lined / etc...), you could speak with your inspector about welding and inspecting the joint as a "goldedn joint".[/li]
[li]Fabricate and ship the two halves to site. Perform the weld at site and hydrotest the completed vessel. Complete all ASME documentation (stamping / U-1 forms / etc...) at site. The complexity here is that many ASME shops do not have available field services to perform the field weld, which limits the avaialble number of shops to take on this work.[/li]
[/ol]

Take your pick...