Welded connection on structural members of supported cone roof tank

[sollapalooza]

Hello all,

Recently I have modified a splice connection between 2 structural members of a supported cone roof, changed it to weld connection. However, what kind of NDT is compulsory on this weld? Section 8.1.1 do not say anything regarding weld of structural members;

8.1.1 Application
Radiographic examination is required for shell butt-welds (see 8.1.2.2, 8.1.2.3, and 8.1.2.4), annular-plate butt-welds
(see 8.1.2.9), and flush-type connections with butt-welds (see 5.7.8.11). Radiographic examination is not required for
the following: roof-plate welds, bottom-plate welds, welds joining the top angle to either the roof or shell, welds joining
the shell plate to the bottom plate, welds in nozzle and manway necks made from plate, or appurtenance welds to the
tank.

Thanks in advance

EDIT: Upon checking with Annex T:
MT is required for Permanent attachment welds and temporary weld removal areas on Group IV, IVA, V, and VI materials, unless tested by liquid penetrant, or vice versa. The members are S275 beam, falls under Group IV.

Is it safe to assume MT/PT is adequate, without RT?

 

[IFRs]

API 650 is silent on NDE for spliced structural mambers. It does require the use of ANSI/AISC 360 using ASD only, have you looked there and in the standards referenced in AISC 360?? Annex T typically applies only to welds on the pressure boundary, see the referenced setion for each NDE requirement.

 

[JStephen]

The MT clause mentioned is pertinent to shells only, not roof structure.
The allowable strength is to be determined per AISC-ASD, but full compliance with all aspects of the AISC code is not required.

 

[Dhurjati Sen]

Dear sollapalooza,

Why did you modify? Is this a new tank? If not, then why follow 650?

NDE is fairly simple, carry out LPI of the final weld. However, the modification needs to be vetted by the designer.

Regards.

DHURJATI SEN
Kolkata, India