Quck answer
To calculate the length of a pipe, follow these steps:
1. Measure the diameter of the pipe using a tape measure or calipers.
2. Measure the distance between the two ends of the pipe.
3. Convert the diameter to the appropriate units if necessary (e.g., from inches to centimeters).
4. Use the formula: Length = π x diameter x number of turns + distance between ends.
5. Plug in the values and calculate the length of the pipe.
Remember to use the same unit of measurement throughout the calculation.
There are situations where measuring the length of a pipe with a ruler or tape measure is not possible. This could be because the pipe is buried, submerged, or inaccessible. In such cases, it is possible to calculate the pipe length using other related measurements.
Method 1: Internal Volume
Step 1
Identify the specific pipe line. For example, let’s consider a 1-inch Schedule 40 steel water pipeline in an industrial facility. The length of this pipeline is unknown. However, if it requires 9.24 gallons of water to fill the pipeline completely, we can calculate its length.
Step 2
Calculate the volume of one foot of 1-inch Schedule 40 steel pipe. The published data indicates that the internal diameter is 1.05 inches. Using the volume formula for cylinders, V = (diameter/2)^2 x pi x length x 7.48 gallons/cubic foot. By substituting the values, we get V = (1.05/2)^2 x 3.1416 x 12 = 0.0449788 gallons/foot of pipe.
Step 3
Determine the length of the pipe by dividing the internal volume (9.24 gallons) by the volume per foot of pipe (0.0449788 gallons/foot). The result is 205.43 feet. Considering that the pipe is butt-welded from the outside and has no fittings or intrusions, this length is accurate.
Method 2: Flow Head-Loss
Step 1
Identify the specific pipe line. Using the same example as in Method 1, let’s consider a 1-inch Schedule 40 steel water pipeline in an industrial facility. When a precise flow of 10 gallons per minute (gpm) is metered through the pipe, the entry flow pressure of 60 pounds per square inch (psi) drops by 5.91 psi. We can calculate the length of the pipe based on this information.
Step 2
Refer to the pressure-loss data for 1-inch Schedule 40 steel pipe. The data shows that at a flow rate of 9.5 gpm, water loses 2.6 psi per 100 feet of pipe.
Step 3
Adjust the published data according to your measured example. Since the flow increases proportionally with the square root of the pressure difference, we can use the formula (10 gpm/9.5 gpm)^2 = 1.108 to calculate the proportionally greater pressure loss for your length of pipe due to the increased flow. Multiplying 2.6 psi by 1.108 gives a calculated loss of 2.881 psi for 100 feet of your pipe at 10 gpm.
Step 4
Determine the actual length of your pipe by dividing the measured pressure drop of 5.91 psi by the pressure loss per 100 feet of pipe (2.881 psi/100 feet). The result is 205.14 feet of pipe based on pressure drop. This is reasonably close to the calculated length of 205.43 feet from Method 1.
