Pipe fitting bend radius

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Pipe fitting bend radius

Postby dbolton » 11 Dec 2012, 11:20

Can someone please shed some light on an issue for me.

Working with Revit MEP, I am creating new pipe fittings and have come stuck on one parameter (how to obtain or how to calculate it)

On a fitting that has a bend (an elbow say) where that bend is governed by a “Centre Radius” parameter to keep the bend consistent when the fitting is used on various sizes of pipes and at various angles. This “Centre Radius” parameter is governed by values that are obtained from the lookup table for the fitting but I can’t find how to calculate this value to put it into a lookup table in the first place. I am trying to create a new fitting and lookup table for a new pipe type, the MEP tutorial gives you the "Centre Radius" distance and it gives you the lookup table with all the values already entered for each pipe size, but doesn’t actually tell you how to calculate it for new pipe sizes. I have also tried using an existing fitting and lookup table that I can re-name, but I want to add a few more sizes to the lookup table but I can’t find that one measurement or how to calculate it, I have tried to work out how they did the existing ones but can’t seem to crack it. This measurement is integral for the bend to perform properly, if it is done incorrectly the bend will still get inserted when you draw two pipes at an angle but the centre part of the fitting, the bend between the two couplings, gets omitted and of course the pipe fitting then doesn’t look right.

I was hoping that someone out there, with more MEP experience than me, was able to explain to me how I calculate this value so that I can put it into the lookup table for new pipe sizes.

Any assistance would really be appreciated.

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Re: Pipe fitting bend radius

Postby Hendre Roesch » 30 Sep 2013, 14:46


I did not use lookup tables for pipe fittings that I have created. Instead I just have the formula in the family. Either way, it doesn't matter too much.

I use the "Carbon Steel Buttweld Fittings to ASME B16.9, B16.28 & BS.1640" Pipie Data Chart to get these dimensions from.

The formula is:

if(and(Nominal Diameter = 15 mm), 38 mm,if(and(Nominal Diameter = 20 mm), 38 mm,if(and(Nominal Diameter = 25 mm), 38 mm,if(and(Nominal Diameter = 32 mm), 47.5 mm,if(and(Nominal Diameter = 40 mm), 57 mm,if(and(Nominal Diameter = 50 mm), 76 mm, If(and(Nominal Diameter = 65 mm), 95 mm, if(and(Nominal Diameter = 80 mm), 114 mm, if(and(Nominal Diameter = 90 mm), 133 mm, if(and(Nominal Diameter = 100 mm), 152 mm, if(and(Nominal Diameter = 125 mm), 190 mm, if(and(Nominal Diameter = 150 mm), 229 mm, if(and(Nominal Diameter = 200 mm), 305 mm, if(and(Nominal Diameter = 250 mm), 381 mm, if(and(Nominal Diameter = 300 mm), 457 mm, if(and(Nominal Diameter = 350 mm), 533 mm, if(and(Nominal Diameter = 400 mm), 610 mm, if(and(Nominal Diameter = 450 mm), 686 mm, if(and(Nominal Diameter = 500 mm), 762 mm, if(and(Nominal Diameter = 600 mm), 914 mm, 5 mm))))))))))))))))))))

Should be able to paste the above in and it will work for you.

I just noticed that you posted the question almost a year ago. Oh well...
Hendre Roesch
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