Section VIII Div. 2 Part 5 - Hydrotest 2

[reesh]

Hello,

I'm looking for some help on theoretical background on a subject. I'm performing an elastic FE analysis to Part 5 of Section VIII, Div. 2. I have a government reviewer (Canadian CRN stuff, another long story) who is insisting that analyzing for hydrotest conditions is required under Part 5 for an elastic analysis. I've tried explaining to him that it's not in the required load combinations in Table 5.3 for an elastic analysis (though it is in Tables 5.4 and 5.5 for load limit and elastic-plastic). I'm not making much headway with him on this.

I'm looking to find out a little more as to why this is the case from a theoretical background. Any references that could be listed would also be greatly appreciated. I'm hoping to maybe convince him using this route.

Thanks!

 

[TGS4]

reesh - this is a complicated subject, that is currently in a state of flux at the Code Committee level.

Currently, the rules are such that there is no requirement for evaluating the hydrostatic test condition in determining Protection Against Plastic Collapse using the Elastic Stress Analysis Method. My justification for saying this is that there are no limits to any of the stress categories provided.

However, such a lack of requirements conflict with 4.1.6.2. Furthermore, the Required Factored Load Combinations in Table 5.4 and 5.5 are inconsistent with 4.1.6.2, because neither Table 5.4 or 5.5 include the actual test pressure. Therefore, the Code Committees are evaluating a proposal (I am the Project Manager) to rectify these problems - under BC11-1266. It is my hope that these changes will proceed for the 2017 Edition and remove this problem/ambiguity.

If you require additional assistance, my contact info is in my member profile - click on my username.

 

[reesh]

Thanks! I'm going to take advantage of your offer and get in touch with you later this week as I have a couple of questions.

 

[Kikeg27]

Hello,

I'm having the same problem regarding to the lack of loadcase combination for the hydrostatic test condition for the plastic collapse evaluation with an elastic analysis in table 5.3.
¿Would it be appropiate if I use Ps (according to table 5.2 - Static head from liquid or bulk materials) with my Hydrotest liquid pressure as the hydrotest load and use this load cases?

P + Ps(Phydrotest) + D + L
P + Ps(Phydrotest) + D + L + T
0.9·P + Ps(Phydrotest) + D + 0.6·Wpt
0.9·P + Ps(Phydrotest) + D + 0.75·(0.6·Wpt) + 0.75·L

According to Table 5.1 The loading condition of pressure testing shall include:
- Dead loads
- Piping loads and pressuse thrust
- Applicable live loads (excluding vibration and maintenance)
- "Pressure and fluid loads (water) for testing and flushing equipment and piping unless a pneumatic test is specified."
- Wind loads

I think there are all of them covered with these load case combinations.

If I could take advantage too of your offer and contact you for a few doubts it would be a great help.

Thanks in advance

 

[TGS4]

Kikeg27 - you are welcome to contact me.

The design load combinations that you list above are not appropriate for the test condition, nor do they provide appropriate limits for the corresponding stresses.

Unfortunately, I am a little constrained in sharing (on a public website such as eng-tips.com) what the proposed changes are until they have passed and will be included in the next Edition of the Code. Nevertheless, at the Code Committee meetings next week in Henderson, NV (

https://w3.smartreg.com/webreg/ASME_BCW0216/),

WG-DBA (VIII) will be discussing this topic at our meeting on Monday that goes from 8am-5pm.

 

[jte]

One thing to remember for those with an interest in code committee activities is that the meetings (well, most) are open to the public at no charge. The VIII Working Group Design By Analysis is among the vast majority which is open.