Using blind during hydrotest

[ashfaqanwer]

At our location, during hydrotest activity we are using flat plate blinds at the test limits with a groove connection to the pipe.
Is this allowable as per ASME B31.3? Or is it advisable to weld an equal schedule end cap or blind flange for end connection?

[ranagr]

Customized blind flanges are acceptable as per code.But for design thickness of blind and pipe to cover/blind weld joint geometry should follow code requirments.As per B31.3 Para 304.5.2 customized blind flanges/covers should design as per UG-34 of ASME Section VIII, Div.1.

If end cap of equal schedule is availbale, this can also solve your problem......since no calculation is required

[ashfaqanwer]

Whats about using of flat plates as blind? Is this practice unacceptable? What does code say about this?
For a project where about 10-15 hydrotests are being undertaken in 24 hours, would it be possible to use customized blind flanges? I agree that if available, standard blind flanges as per testing pipe schedule can be used.

[ranagr]

Using customized blind flanges is cost effective approach.Most of construction sites use this approach to minimize the construction cost.

Please go through figures of ( Fig-UG34) these are customized flanges and can be fabricated from plates.Consider you are testing of equipments where rectangular opeings are present and you need a blind flange, in that case you should do code calculations. (Since UG-34 apply both for circular or non circular heads and covers).If you have sufficent inventory of standard blind flanges Compatible with subjected piping spools which can be reused (for other jobs of hydrotesting in future/or other equipments as well) after hydrotesting then go for standard flanges.Otherwise, procurment of huge inventory of blinds only for hydrotesting make no sense.

Actually customized blinds (made from plates) extensively used for these kind of jobs.Most of times in equipments we have used customized blinds for large openings like 36, 44, 54,66 or 76 inch.

Please let me know your email adress, I will send to you Quality Bulletin of customized flange failures (occured in one of Aramco site) for your information.Please consider aramco inspectror recomendations if you go far these type of customized blinds......

[ashfaqanwer]

RGR,
Forward me the literature regarding customized flanges at ashfaqanwer@thepetrostreet.com.
I understand that UG-34 highlights the requirements for flat heads and covers for pressure vessels. When in piping, we have to blind the pipe end with a flat head, same UG-34 is applicable?

[ranagr]

Let first discuss Pressure piping code ASME B31.3.There are three statements for designing of blind flanges. (Generally say piping components)

1-Para 303 of ASME B31.3 refer pressure temperature rating for using standardized piping components. I.e. no detailed calculation required. (Para 303 refer Table 326.1 for piping components standards/specifications).You can see in this table ASME B16.5/16.47 present which refer standard flanges.

2-Para 304 of ASME B31.3 apply for customized blind flanges which are not in accordance with Para 303 and Para 304.7.2 of ASME B31.3.
Para 304 of ASME B31.3 refer ASME Section VIII, Div.1 design approach UG-34 to design customized blinds.

3-Para 304.7.2 of ASME B31.3 apply when code rules of para304 or para303 are not applicable. E.g. piping in fatigue services/cyclic loading/blinds or flat head configuration is not as per Fig-UG34 etc.One of approach to design these types of flanges on Ansys software with ASME Div.2 approach.

[ashfaqanwer]

Great.
I have found that.
So the last point, if a flat plate as designed using UG-34 and with attachment details as per Fig. UG-34, that can be used as a blind?

[ranagr]

Ya.you are right.

[ashfaqanwer]

Thanks RGR for your help.

[moe]

I have enjoyed reading the above inputs, very interesting..
here are my 2 cents
- Plain test blinds shall only be used between bolted flanges.
- At test pressures above 100 barg, test blinds shall have serrated faces as per ASME B16.5.
- Paddle blinds or spectacle blinds shall be used to isolate the test sections.