Pipe Loop

This app is for sizing pipe loops and pipe legs (illustrations are shown below). Both US (English) and metric calculations are available on separate tabs. App does not directly convert...you input all in metric and results in metric, or input all in English and results are in English units.

You enter the pipe size outer diameter (O.D.) in inches (or mm), the max operating temperature in degrees Farenheit (or Celsius), and the straight distance between the pipe anchors that you are evaluating the pipe between (in feet or meters). The app calculates the following:

A) Thermal Expansion (expressed in inches per 100 ft. of pipe or mm / 100 m)
B) The minimum length of pipe required between anchors (according to B31.3 Paragraph 119.7.1)
C) The difference between your distance between anchors and the calculated min length of pipe between anchors will net you the added pipe feet required.
D) Then the app reports the length of the loop that has to be installed, and the width. The length, "L" is = to 2x the width, "W".

For the iPhone app, on a separate tab (on iPad it's all on the same tab), you also enter the allowable hot stress (in psi), and the app will calculate the Modulus of elasticity (in psi) and the length of the leg ("L") for your pipe leg.

The app is good for three basic materials of construction. The first is CS thru 3Cr, labeled simply as "carbon steel" in the app. The second is 5Cr-Mo through 9Cr-Mo, simply labeled as "Chrome Moly" in the app. The third is Aus. SS, simply labeled as "Stainless Steel" in the app. You can click on the button to the right of the material listed and toggle through these three selections.

The equation correlations embedded have an R-squared values = ~1.000 for the materials thermal expansion in./100 ft.

The data range used was for piping from -325 degrees F (yes, that's a negative 325) up to + 1400 degrees F. The resulting equation is a 4th degree polynomial.

The modulus of elasticity data was extracted from data ranging from -100 degrees F (negative 100) to + 1100 degrees F. The R-squared values for the equations used are greater than 0.999 and the graphs fit quite well (i.e., there is no statistical "lack of fit").

Note that these calculations are to be used as a general guideline and not a final determination of the actual stresses in the pipe. A formal stress analysis is required to determine the actual stresses in the pipe (and this app does not do that for clarity sake). This is a shortcut tool and should be used as such. For allowable hot stresses, see code stresses for more accurate allowable stress. 15,000 psi (as defaulted in the app) is a good starting point only.

更新履歴
Update the leg sizing app so that for low temperatures, it doesn't give you an error.