MDMT and insulated Vessels

[nuche1973]

Does section UCS-66 apply to a non-standard insulated vessel? I have an insulated dust collector that is in a cold climate. The housing thickness inconjunction with the coldest ambient temperature dictate Impact testing per UCS-66. However, the collector is insulated and an insulation is not listed as an exemption factor in the Code. Or am I looking in the wrong location? Any help would be appreciated.

 

[Duwe6]

MDMT applies to the operating temperature of the vessel, not the ambient temp outside the insulation. Does this vessel *operate* at less than -20 deg F? This includes startup. Also, does the dust collector work at a pressure greater than 15 psig? If not, it does not fall under Sect VIII, unless you want it to.

 

[nuche1973]

The lowest temperature (-38 deg F) is a non operating site temp (ambient temperature) and working pressure is 1.3 psig. I am using Sect 8 as a guideline, since an actual Dust Collector Code doesn't exist and I want to be thorough. Thanks for the response.

 

[jte]

Don't forget to include startup conditions. The insulation will help (in general) with the metal temperature - which is what we are discussing.

If the potential exists that the dust collector will have a low metal temperature during startup then that is something which must be considered in the MDMT evaluation. You will likely find that the low working pressure - thus stress - will be of substantial benefit in determining the MDMT.

jt

 

[nuche1973]

jte & Duwe 6, thanks I appreciate the help.

 

[Shmulik]

Duwe,

Sorry!
The –20°F temp. exemption was valid only before the 1987 Addenda of ASME VIII Div. 1 was issued. The 1987 Addenda mandated new toughness requirements and specified new minimum design metal temperature requirements.
The code no longer allows an automatic exemption from impact testing for temp. above –20°F. The designer must evaluate each component material used in the design of the vessel separately acc. to the rules of UCS-66.
Impact test is mandatory unless exempted by the rules of UG-20(f) or UCS-66 / UCS-68.

 

[mqadir]

First of all check the scope of ASME Sec VIII div.1, is the pressure greater than 15 psig and etc. only than u can use UCS-66, personaly i believe it is not in ASME Sec VIII, Div. 1 scope.


THanks

 

[mqadir]

First of all check the scope of ASME Sec VIII div.1, is the pressure greater than 15 psig and etc. only than u can use UCS-66, personaly i believe it is not in ASME Sec VIII, Div. 1 scope.


and yeah incase of insulated vessel the MDMT is not determined by ambient conditions.

THanks

 

[jte]

mqadir-

Welcome to the forum. Keep in mind that your lack of puntuation and use of capitals and "u" instead of "you" reflects on your professionalism.

Consider going to the "My Stuff" tab - Profile - then filling in a few sentences to tell folks what your background is. It helps for us to know what your perspective on pressure vessels is. If you click on the "jte" at the top of this post you'll see what my background with pressure vessels is.

Finally... A vessel need not have a MAWP exceeding 15 psig to have a "U" stamp. I this particular case, the original poster already stated that he is looking at Section VIII as a guideline, so it doesn't really matter. And... ambient conditions should be considered for a startup scenario. If the vessel has been out of service in a cold environment for a month, chances are that the steel may have been cooled down a bit.

Again, welcome to the forum...

jt