Impact testing criteria for vessel supports (skirts/saddles) 1

[marty007]

Hello,

We are building a few ASME VIII-1 pressure vessels, some on skirts and some on saddles. As the skirts and saddles are non-pressure parts, they are not covered by ASME (aside from general guidance in appendix G and weldability requirements, etc...).

Is anyone aware of any codes that would relate to impact test requirements for such components in Canada (or US for comparison)?

Thank you,
Marty

 

[metengr]

What does the client specification require?

 

[doct9960]

marty007,

According to UCS-66 of ASME Section VIII-1 and paragraph 3.11 of ASME Section VIII-2, components and attachments that are "essential to the structural integrity of the vessel" must meet Code requirements for material toughness.

There was an interpretation on the old ASME Section VIII-2...

Interpretation: VIII-2-83-01
Subject: Section VIII-2, AM-204
Date Issued: July 26, 1982
File: BC81-362

Question: Under the requirements of AM-204, would the portion of a support structure skirt or saddle welded to the vessel be regarded as a structural member essential to structural integrity?

Reply: Yes.

Paragraph 3.11 of the current ASME Section VIII-2 is similar to paragraph AM-204 of the old VIII-2.

ASME Section VIII, Div. 1 does not have a similar interpretation, but most owners in Alberta, Canada require that Div. 1 vessel supports meet the impact test requirements of the Code at -40°C or -40°F. I can't say if this is typical for the rest of the Owners in Canada. If there are no Client requirement, it's up to the vessel engineer's judgement.

 

[marty007]

metengr: There are no requirements in the client specifications relating to this specific question, we are to follow ASME VIII-1. I am just trying to confirm if there are any code requirements.

doct9960: Thank you very much for the in-depth response! That was very helpful.

I work in the ASME world, but this makes me wonder how structural engineers handle this. How would MDMT be handled for say a steel bridge in the far North of Canada? Is it handled through codes, or just purchase specifications?

Cheers,
Marty

 

[An5]

Marty 007,
Fig.UG-66 shall be used for the requirement of impact test on structure parts of a pressure vessel. The structure parts may not be evaluated per Fig. UCS-66.1 for MDMT reduction as the parts come with different stress criteria for evaluation.

Bridge code and material spec have requirements on impact test.

An5

 

[myck]

To ensure integrity of structural material, therefore impact test shall be required. Materials may fail to a certain temperature which is a function of thickness. You may try also to check the ASTM equivalent material requirement for this.