Bleed Rings in ASME B31.3 Piping System 1

[langco]

Client request to use a bleed ring between flanges. Since bleed rings are not listed as a standard component, what would be the best approach per 304.7.2?
I know they are used quite often per part(a) but do not have anything really to substantiate the use.

Bleed rings required on CL 150, 300, 600 and 900 natural gas service.

Any thoughts?

Thanks

 

[unclesyd]

We have some in use on a vaporized heating medium (Therminol) system. I can't recall any discussion on the installation or viability in use and as far as I recall I can't remember any of them being used as all our units double block and bleed systems, double valve sample system, and separate vacuum system. There was some mention that they would be used to drain the system in very cold weather which doesn't checkout as there is appreciable slope in all lines, vapor and liquid for draining.

Some more information:

http://www.mackiron.com/products/blinds/brinfo.htm

http://www.wiremasters.com/SubFolder/02 bleed rings.htm

 

[langco]

Thanks for the info. I was thinking, I wonder if you can just 'model' the ring as a piece of thick pipe with a socket-weld connection as a fabricated assembly which would comprize of pipe and a listed fitting.

 

[unclesyd]

Would your program handle the ring as an orifice plate or "Dutchman", a thick metal gasket, or line blank?

Are you talking about RF or RTJ flanges?


I don't know how our piping system design handles the rings as they came with the original construction. All our rings are installed in RTJ Class 300 flanges.

 

[langco]

I am not considering a program for analysis etc. Just trying to justify the ring in accordance with B31.3.

I am considering a ring flat faced on both sides fit in between a set of RF flanges. It is pretty intuitive that it satisfies the code requires, but intuitive just is not going to cut it for satisifying a non-standard component. I do not have access to ANSYS these days nor would it justify such an evaluation. I was hoping that I was missing something elementary.

 

[eadwine]

Bleed Rings have been used for years in installations all over the world. Off the shelf varieties meet the code requirements for the flange class in question. Most often they are used to reduce fit up dimensions in tight spaces and to reduce the cost of having to use double flanged pipe spools.

Hope this helps.

 

[langco]

eadwine - would you be able to direct towards a supplier where they clearly specify that it is rated per the flange class?
All of my google searches have rendered me suppliers of bleed rings but unfortunately never any reference to a design standard. Thanks

 

[unclesyd]

All you have to do is compare the dimensions, it is quite evident that the RTJ's have got to be fabricated to required dimension.

 

[eadwine]

langco, Try the Mack Iron Works in Sandusky Ohio or any of the specialty Pipe Fitting Manufacturers. Don't simply trust to the Internet, call them!

 

[bernoullies123]

The bleed ring with a hole could be analysed as short-thick piece of pipe which is covered in Section 304. The pipe thickness can be checked per 304 and the hole as per a connection of 304.3.2.

 

[pennpiper]

Look here for details of "Bleed Rings"

http://www.mac-weld.com/FlushRing-BleedRing/FR-BR-BleedRing.html

 

[JLSeagull]

Bleed or flushing rings are commonly used for checking the calibration for level instruments. However, the rings are normally installed on the instrument side of a vessel block valve thus fall within the instrumentation standards; and outside ASME B31.3.

 

[unclesyd]

Does ASME 31.1 or 31.3 really care what you put between two flanges?

 

[Robys]

Bleed rings, or drip rings, are commonly used to branch a 1/2" or 3/4" assembly, like drains or pressure taps, where you can use a flanged connection to save space and components. I used bleed rings with 1" holes also.

Here you can see full details:

http://www.meccanicapadana.it/intranet/libretti/libretto9-05-1.pdf

 

[rneill]

You might try finding a manufacturer of bleed rings that has obtained a Canadian Registration Number for their product. A Canadian Registration Number would signify that the design of the component had been submitted to a regulatory authority and had been approved as acceptable for use in pressure piping systems.

This would give you something tangible to substantiate the design and acceptability of the bleed ring.

 

[moltenmetal]

rneill, that link (to Mac-Weld Machining) has already been given. They do have CRN#s for their flushing/drip rings and similar components. They'd be best to contact if you want to know on what basis those CRNs were granted (ie. whether calcs or proof testing or some other means were used to justify the P/T ratings).