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Compact Reducing Flange

Compact Reducing Flange

Compact Reducing Flange

I have a #2 fuel piping system #150 where space between valves is limited. I need to create some room by removing a 6x4 conical reducer and I was thinking of installing a compact reducing flange in its place. I have used these before on instrumentation on top of tanks but never in the piping.


Any advice is appreciated,

RE: Compact Reducing Flange

What is your question?

RE: Compact Reducing Flange

Sorry. Would the compact flange reducer be an acceptable replacement for a conical reducer to create some additional space?

RE: Compact Reducing Flange

Use a 6" blindflange, drill a hole dia 115 in it and weld the pipe to it.

RE: Compact Reducing Flange

The ductile iron component might run you afoul of some code rule or another. The A36 carbon steel component isn't made from a forging but from plate, and I would think that would make it a non-legitimate component. I don't think either component is listed in B16.5. However, these components (in ductile iron) are commonly used in plastic-lined construction. In those cases, P/T ratings are supplied by the manufacturer (i.e. Crane Resistoflex) rather than relying on the components complying to an ASME standard such as B16.5. In my opinion, the concerns aren't really whether or not it will work and be safe (depending on temperature and service of course, which I know virtually nothing about in your case), but rather one of code compliance. Others may be able to advise you more specifically if you provide additional information.

As to the turning a blind into a reducing flange as europipe suggested, unless I'm mistaken, that's only legit if you use a hubbed blind. B16.5 will only allow a plain blind to be used within a certain size range, and 6x4 is definitely too large to comply. Hubbed blinds exist and can be bought- but that doesn't solve your problem as neatly as the reducing filler flange would I would imagine.

RE: Compact Reducing Flange

We had the same issue some years ago. As the european market, for some reason, has less suppliëren and/or stock of some typical ASME Or MSS SP fittings, we need a bit more creativity every now and then to come up with a solution.
The supplier who did the vessel under which the the reducing flange was placed, made the same solution as you listed, but did the calcs based on ASME VIII-1, and more specifically app. 2 for the flange part. And, as far as I can remember, they also drilled a radial hole into the conical subsection halfway the fitting, to insert a thermowell. It required some calcs, but once you figure that out, the rest is simple. And you can easily make up a drawing and order a pretty straight forward maxhined part.

RE: Compact Reducing Flange


What is code of construction? Any other requirements from AHJ?


RE: Compact Reducing Flange

I've seen these things used for low pressure water connections connecting iron fittings to pe, but they are not pressure rated and don't follow any code.

What fluid and pressure are you talking about?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Compact Reducing Flange

Again, no need to re-invent the wheel here. Crane Resistoflex supply these reducing flanges in both ductile iron and cast steel, for use under B31.3 in some of the most hazardous services you can think of- i.e. services so corrosive that they require PTFE lining. They are doing so in accordance with a set of rules, and can be contacted to discover the basis for those rules.

RE: Compact Reducing Flange

Learn something new - http://www.resistoflex.com/steelredfiller.asp?unit... Not come across these before from a reputable supplier. Pretty thick in places.

Would be interested to know which rules they used and how they designed them. Maybe ASME VIII?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Compact Reducing Flange

You can not attached a DN100/4" pipe to a DN150/6" class150 blind flange. Not permitted by the flange code B16.5. But you can if you design and add reinforcing.

RE: Compact Reducing Flange

You CAN make a 6x4 reducing SLIP ON flange from a hubbed blind- which is how the flange manufacturers make such a flange. Based on actually speaking to flange manufacturers, they don't produce such (small) flanges from pierced forgings- they stock hubbed blinds and machine the reducing outlet to order. I'd already mentioned what KevinNZ reinforced, which is that B16.5 doesn't permit the 6x4 size reduction to be done with an ordinary blind flange. You can also buy a 6x4 reducing weld neck, if you can find one. Or, if the sum of your applicable codes permit, you can buy the ductile iron or cast steel studded outlet reducing filler flange noted above.

RE: Compact Reducing Flange

Interesting ... never seen these before. Is there any reason to not just use a code-compliant 6"x4" reducing weld neck flange, as moltenmetal mentioned?

RE: Compact Reducing Flange

One reason to not use 6x4 reducing WN flanges is availability, as MM rightfully pointed out. I recently had an enquiry for a reducing flange: we decoder to go for a high blind flange since it was better available.

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