Change of long. weld seam angle due to wrong manhole orientation

[isopvsw]

Hi everyone,

I have to find out if there is any provision within AS 1210-2010 for staggered angle requirements.

Basically, our supplier has not orientated manhole at correct orientation on last shell of vertical air receiver. The shell is attached to head. Rather than going to scrap shell+head I would like to see if we can still use it without any costly affair.

The vessel is Vert. Air Receiver with four long. welds, all are staggered by 90 deg. See attached sketch.

Even if we rotate this last shell, seam angle for the last one will change.

Does anyone have come across such situation before?

 

[bernoullies123]

AS/NZS 1210-1997 (don't have 2010) doesn't stipulate this kind of information. This is covered in AS 4458 section 8.3.3 Location of joints.

Basically you can leave the manhole and you have an extra one. Or you can rotate that strake ensuring that L1 and L2 are spaced per the above clause (min. 5t). Providing it is only a manhole and not a process connection, you should be able to accept it, in the 'general area' (just a few degrees out).

 

[saplanti]

I guess the best thing is to talk to the job owner. The owner may have access problem to the location of the new menhole location, or piping or other equipment might be engaging the new location. Approach the owner honestly. They may accept or reject it.

In case of the rejection, you may have the alternatives above.

 

[gr2vessels]

Am I missing something here, at this stage I cannot see why shouldn't the vessel be turned 180 deg to bring the manway to the correct orientation.
The long seams orientation is not specified by the code, except for proximity of two long seams.. you could even cut the manhole in the long seam if you have no option, including the covering of the long seam with reiforcing pad, following the code recommendations for inspection and testing before welding the pad.
The seams are correctly placed and the manway is far away for any proximity to welds. So what's the problem??
Cheers,
gr2vessels

 

[saplanti]

gr2vessels is right about the approach for the vertical vessel unless you have not opened other nozzle holes. The weld seams can be in any orientation, but it is better not to create crosses between the circumferantial seam s and longitudinal seams, some codes clearly indicate that.

My previous comment was based on the horizontal vessel, and I was not careful in reading the first thread.

Regards,

Ibrahim Demir