PV - Design Life 1

[PVRV]

Several PV have been manufactured, maintained and inspected as per Code requirements. The survey intervals have been reduced to four years and provisions are in place for internal protection (coating + sacraficial anodes). On-line inspection included UT scanning and RBI has been carried out.

Is there any reference to how long these PV can be operated. Bearing in mind they have been in service well beyond their design life; as an example 40 years.

deanc, I would appreciate your feedback on this issue.

Cheers

 

[aybee]

Generallythey can be operated indefinitely,provided they have no internal or external corrosiong, weld cracking or are not subject to fatigue. A prudent operator would do a full check on the fatigue life that the vessel has seen in addition to checking against corrosion as above.
Also Steels get Aged and their ductile transition temperature shifts upwards over time as they get older their ductile -brittle temperature moves nearer to ambient(say 20C) and can be quite high on old vessels such as 40years + so that they cannot be safely pressured at ambient temperatures..if your ambient is low then it may not be safe to pressurise them...this can be more of a problem with low alloy vessels and more so with thick vessels say over 1" thick...if you can take a sample then Charpy impact tests would give you an idea what the present condition of the plate is..hope this helps ..

 

[PVRV]

aybee,

First of all thank you for your responce. In retrospect your suggestion is to conduct DT to evaluate mechanical properties; in several regards fatigue (life cycles, depending on operating parameters) and MDMT considerations.

I was wondering if there is any code requirement regarding operating life span of a PV. As an example, OSHA Regulation 29 CFR, Part Number 1926, Subpart D, standard number 1926.64 App C; PSM requires revalidation of design criterion against latest applicable design code and process stream to ensure that the orginal design did not depart from the applicable codes used today and the current service stream.

My question is: does ASME or NBIC state explicitly what number of service years shall not be exceeded, or a factor against design life else the design life. Or to be in line with your feedback what amount of degradation to the mechanical properties is permissable bearing in mind the implications that this is not a new PV.



Cheers

 

[deanc]

Suggestions:
1.Go to

http://WWW.Nationalboard.org

and have alook at the Draft Addendum for the new NBIC.
2.Visit Nace.org
3.Check Fitness4service.com

Try and obtain a copy of the original code of construction for calculations. Also a copy of the MDR.

Suggest wet fluorescent magnetic particle testing of all weld seams after a thorough cleaning.

 

[deanc]

See RB-9000 in the Addendum. If you cannot obtain this,list your e-mail and I will send it.

 

[PVRV]

deanc,

a)
Yes you are correct. WFMPI and UT (TOFD) was conducted and revealed several cracks at different orientations and depths; repairs have been conducted and several PV were scrapped.

b)
aadsani@kockw.com

Cheers

 

[LSThill]

Dear deanc (Specifier/Regul) May 12, 2003
Regards to your reference: (See RB-9000 in the Addendum. If you cannot obtain this,list your e-mail and I will send it.)

I have 2002 NBIC Addeddum, DATE OF ISSUE: 31, 2002, This is the second sddedum issued for the 2001 edition of the National Board Inspection Code (NBIC), NSI/NB-23

An "A02" appears in the margin of replacement page where a change has been made form the previously published version.

REFERENCE TO RB-9000 in the Addendum what page number?

Leonard Stephen Thill
Leonard@thill.biz

http://www.thill.biz

 

[chicopee]

You do not state if your PV's are of riveted or welded construction and what they are used for. In Massachusetts, lap riveted air tanks must be derated after 10 years of service. After twenty years, factor of safety must be increased to 6.

 

[deanc]

Isthill:

You must go to the NB web site. RB-9000 is not yet published. Do expect to see it soon.

pvrv:

Happy to help. Only opinion,as always.

 

[LSThill]

Hi deanc (Specifier/Regul)

Ok! good call, thank you

Leonard Stephen Thill
Leonard@thill.biz

http://www.thill.biz