Pipelien Flanges- Derate as a function of increase bolt/Stud hole diameter 2

[Termodinamica]

Gentlemen,

What would be the derate of a 12" 900 Series Ansi Flange if I was to increase the bolt hole diameter. Is there a table or a contact that may supply this kind of information.

Additional:
Pipeline application
Purpose: allow additional aligining clearance


Any information will really help me.

Thanks

 

[racookpe1978]

Yes.

Don't do it.

Don't propose it.

Don't allow it.

Don't accept the proposal if somebody offers to do it.

Now, to your specific question: How the blue blazes do you expect someone to answer your question if you provide no sizes; proposed new diameters; fluid pressures, temperatures, service fluid, pressure surges, temperature,service life, future life, application, etc?

Do you professionally think some one would actually answer: "Yes, drill out your your high pressure pipe flanges with bigger holes to make it easier to put them together. It's done all the time and is perfectly safe."

 

[LittleInch]

The de-rate pressure would be zero as you've just made it into scrap metal.

There is no such table in existence.

Rakoope has it spot on - Follow his advise.

If you expand on your actual problem we might be able to advise some alternatives to this illegal and dangerous idea.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[XL83NL]

Just. Dont. Do. This. PERIOD

 

[Termodinamica]

I will not take any risk or put any one else in danger. Those flanges will not be drilled under my direction.

Thanks

 

[LittleInch]

Caperuzo,

Without labouring the point, if you pose a similar question again, please add in your own thoughts on the issue, whether it is a real issue or a general question and give as much info as possible. Some really kooky ideas appear here from time to time and before you reply to a post like racookpes, which I personally thought was spot on,, take a breath, have a break and then think again before pressing "submit post".

Some things get lost in posts and they can be misinterpreted, but generally be polite and respond in the same way you would in your office and place of work, not as you might down the pub....

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[sjrfc2]

If you look at ASME Section VIII formulas for flanges and Taylor Forge Bulletin 502, the bolt hole size isn't accounted for in flange stresses. The exception is T bolts in slotted flanges. I'm not advocating shoddy alignment/installation but what (technically) would we look at to discourage this? Aside from having to compensate for the large bolt holes with either big nuts or washers, what would tell Caperuzu his flange wasn't adequate if he ran the calcs?