Nonwelded Parts per UCS 66

[JStephen]

Question: If you take a blind flange, and weld attachments for a hinge or davit to it, does it still qualify as a "nonwelded part"? IE, relatively minor welding unrelated to the function of the part. I can think of reasons to work it either way, but just wondered what typical practice is.
Related to that, if any welding at all turns it into a "welded part", can you weld some pointless tab of metal on it just to reduce the governing thickness? IE, weld a 1/4" piece of bar or plate on a 2" thick blind flange, and governing thickness is now 1/4" instead of 2"/4?

 

[SnTMan]

JStephen, UCS-66(a) refers to "attachments which are essential to the structural integrity of the vessel when welded to pressure retaining components".

I think it is ordinary practice to interpret this as applying, when applied to attachments, to those required by Code rules such as nozzle pads as per Fig UCS-66.3(b), and to components such as stiffening rings and rings added as reinforcement at cone-cylinder junctions as per Fig UCS-66.3(f), and perhaps to other construction I am unfamiliar with.

I have never seen UCS-66(a)(1) rules applied to clips, nameplate brackets, pads for supports, hinges and so forth. Except perhaps as required by some overly strict client specs.

So, I'd say your two examples would not be correct.

Regards,

Mike



The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[JStephen]

IE, a blind flange with lug or hinge welded on is still an "unwelded part"?

 

[Rputvin]

If you're welding on a pressure retaining part you're not using an unwelded part.

Non-pressure retaining attachments are noted in the code. My reference chart is to the 2015 edition of BPVC VIII-1, but it lists the following as relevant (structural attachments and skirts specifically);

U-1(e)
UG- 4, 22, 54, 82
UCS-66(a)
UHT- 28, 85
ULW-22
ULT-30
Appendix G

 

[SnTMan]

Stephen, for the purposes of UCS-66, I'd say yes.

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[SnTMan]

I don't think anyone would argue that a 1/8" insulation clip would govern the thickness of the shell it is welded to.

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[r6155]

Do not forget to preheat to 95°C if the blind flange is made of P1 material, see Table USC-56-1
For hinge or davit a NDE is required. Depending on the dimensions, a load test is required.

Regards

 

[SnTMan]

OT...

The problem with sloppy work is that the supply FAR EXCEEDS the demand