Hello,

Do you mean the formula t=pD/2xMaterial Yield?

e.g.

A3 = 15 (Pressure in bar)
B3 = 508 (Pipe O.D.)
C3  = 275 (Material Yield)

D3 = =(A3*B3)/(2*2/3*C3)/10 (Answer of 2.07).

I'm not sure how the answer is affected by the temperature, but you did say a rough answer.

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Hope this helps.
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maybe only a drafter
but the best user at this company!

Thanks, its a start. But as a valve guy, I frequently get questions in which I am given only size and pressure of the dwnstream piiping. Valve noise pends on wt also and the std  pipe tables only refer to size and sch (wt) but doesn't tell me the allowed pressure.

In case anything else come up I'll definetly use your input.

ROBV

RobV,

It's been a while (I used to design natural and Toxic gas compressor systems), but ASME Section VIII, Division 1 (Boiler and Pressure Vessel code) gives that information pertainable to their codes. (It is wholly dependent on the safety factor).  You could do a hoop stress calculation and if you plug in the saftey factor of the yield stress (once again code dependent), you can derive the proper allowable pressure.  Be careful though.  Depending on the prevailing code (B31.8 - Gas transmission, API-611, ASME Section VIII (just to name a few)), the factor changes.  You should be safe using a safety factor of about 4-6 (Life or Limb).

Hope this helps.

RobV,
look in the site below under Vessels -> ASME I -> PG-27

prex

http://www.xcalcs.com
Online tools for structural design

I assume from your description that you are referring to transition pipe or pups attached to weld end valves where the length of pipe is typically about 3' for larger size valves.  Smaller size valves may have shorter pups.

The purchaser should specify the piping code of the mating pipe which in turn gives the formula.  There are variations in code formulas as to what allowable stress, design factors, etc. that you plug into the formula.  For example, the formula for B31.3 uses an allowable stress with a built-in safety factor.  On the other hand, B31.8 uses the yield stress plus a design factor in the formula.

If it is B31.8 then they should also specify the installation class which determines the design factor.  The design factor can vary depending on whether the valve is in a cross country pipeline or in a facility.  Hence the valve manufacturer has no way of knowing unless the purchaser tells him.

I always specify the piping code, grade and wt of the mating pipe.  If the valve manufacter choses to use a lower grade pipe and hence thicker wt then he is responsible for bevelling the ends to match the mating pipe all within the rules of the particular code.

Many companies furnish the pipe to the valve manufacturer when they order several valves so that they can control the material properities of the pipe.  Who furnishes the pipe should always be addressed in the specifications.

Assuming for the moment that you are supplying a ball, gate on other open/close valve and not a control valve then in my opinion the noise generated by the piping is the responsibility of the purchaser.  In these cases I will purchase separately a removable insulation blanket for the valve and special acoustical insulation for the piping.

Back to your orginal question about a spread sheet for calculating the wall thickness.  Once you know the piping code then writing the spread sheet should not take you more than a few minutes.  The biggest time consuming task is to look up the formula and the allowable stresses for different materials which is particular for each application.

Do internet search with keywords such as: piping calculations software spreadsheets. You will find some simple calcs and some real big time savers. Some required many hours minutes to develop.

Hi RobV

Try this site, its free and deals with pipes, vessels etc:-


http://www.xcalcs.com/

regards desertfox