Category: Pipe Diameter Tapes

News about Pipes and Drilling

What Is A Diameter Tape Measure?

Diameter Tape Measure
Diameter Tape Measure

Good question, because most people don’t have any use for one. A diameter tape measure is a measuring tape whose scale is stretched out by a factor of pi. This allows you to wrap it around a round object, such as a pipeline or tree trunk, and read its diameter directly on the scale. You don’t need to divide by 3.14159.

Here are some other names that people call these tapes:

  • pi tapes
  • circumference tapes (a misnomer)
  • pipe tapes
  • Lufkin pi tapes
  • OD tapes
  • outside diameter tapes
  • pi-Cobra tapes
  • pie tapes

The Most Essential Tool That Our Foresters Need is a Diameter Tape Measure

Diameter Tape Measures for Foresters
Diameter Tape Measures for Foresters

When you think of a logger or forester, what is the first tool that comes to mind? Probably a chainsaw, right? Well the other tool that they use on a daily basis is a diameter tape measure. What exactly do they use this specialized tape measure for?

  • To wrap about tree branches, logs, and trunks to determine their diameter without cutting them
  • To help estimate the age of the tree
  • To determine the value of the tree if it’s being logged
  • For landscapers, it also helps calculate the amount of fertilizer needed

To be consistent, all loggers measure standing trees with their diameter tape measures at Diameter Breast Height (DBH), which is 4.5’ above ground.

Lufkin Diameter Tape Measure
Lufkin Diameter Tape Measure

How Would You Survive Without Your Pipe Diameter Tape Measure?

A New Use for a Pipe Diameter Tape Measure
A New Use for a Pipe Diameter Tape Measure

Your pipe diameter tape measure is probably the most valuable and simplest tool in your toolbox. It will tell you the outside diameter of a pipeline (or your arm) when you wrap it around the circumference. What if you lost your pipe tape? How would you measure the diameter of a pipe or any round object?

  • Use a regular tape measure, if it is flexible enough to wrap around the pipe. A carpenter’s tape is made to stay stiff, so it won’t work in this case. Since the end hook won’t let you lay the zero mark against the pipe, you would have to start at the 1 or 2 inch mark. Read the circumference and divide by 3.14159. That’s a lot of trouble.
  • Use an expensive caliper, transfer the reading to a measuring tape, perhaps, then divide by pi. That’s a clumsy way of doing it.
  • Get a real expensive micrometer. Since they have a narrow range of measuring (1 inch), it would have to be a certain size to begin with. Then measure the diameter directly. Reading the markings on a micrometer is not the easiest thing to do. You have to read the shaft measurement, then add the tumbler measurement to it.

So, hang on to your pipe diameter tape measure and it will save you a lot of trouble.

3 Mysteries of the Diameter Tape Measure

Mysteries of the Diameter Tape Measure
Mysteries of the Diameter Tape Measure

The diameter tape measure easily figures the diameter of a pipe or pipeline. All you have to do is wrap it around the pipe, and read off the diameter. Here are its mysteries..

    1. Why is the “zero” mark not at the beginning of the tape? It is a couple inches away from the beginning of the tape.
    2. Why does the end of the tape have a “loop” instead of a “hook”?
    3. Why are some calibrated in 100ths of an inch, and some in 64ths of an inch, and some in millimeters?

     

ANSWERS:

  1. By having the zero mark away from the beginning of the tape, you can easily line up the other part of the tape to the zero mark.
  2. Since zero is not at the end of the tape, there is no need to have a hook there. What is helpful, is to have a metal loop to hold onto, when wrapping the tape around the pipe.
  3. Different strokes for different folks. Automotive repair people prefer the 64ths of an inch calibration. Oilfield people prefer the 100ths of an inch version. And of course, some people use the metric system of measurement.

 

How Would Your Customer Use A Diameter Tape Measure?

Let me count the ways…

  1. His car heater hose needs replaced. He uses your diameter tape measure to find what size to buy, before he actually removes the old hose.
  2. Your customer is a plumber, and needs to know the outside diameter of a pipe, so he can get a new pipe before he disconnects the old one.
  3. Your customer is an HVAC installer, and needs to know the diameter of a galvanized pipe so he can buy more, to finish the job.
  4. He has a boat, and needs to buy a new bilge hose before he removes the old one.

    Want To Know The Diameter of Your Arm?
    Want To Know The Diameter of Your Arm?
  5. Your customer sells trees from his nursery. He wants to pick out the trees that are at least 2 inches in diameter, so he can dig them and offer them for sale as 2″ trees.
  6. Your customer wants to keep track of the diameter of her biceps, as she is in a fitness program.

So, to advertise your company logo on a gift item, try a diameter tape measure.

A Big Secret About the Diameter Tape Measure

The Diameter Tape Secret
The Diameter Tape Measure Secret

Diameter tape measures are made for wrapping around pipes and poles, to find the diameter. That’s a good enough reason to keep one in your tool box, garage, and vehicle. But there’s one feature that no one talks about, until now….

The other side of the diameter tape measure is a regular tape measure, in inches or centimeters. It measures length, not diameter. So, even though it is a special tape, it is also a handy every day tape, too. Lufkin, and the other manufacturers, thought of everything when they designed these handy pocket tapes. Everyone should have one or two.

Lufkin Y906PD pipe diameter tape measure, not Barlow W906PD Lufkin Diameter Tape

 

What Will Pipe Diameter Tape Measures look like in 2030?

Measuring Techniques
Measuring Techniques

There are distance measuring apps out there, but measuring the diameter of a pipe presents a unique measuring situation.

  • Calibration. There will need to be some way of checking to see if the app is working correctly. You will need to measure a known standard to see if the app is measuring right. If not, there needs to be some way of calibrating or adjusting the reading, to make it accurate. In other words, if you measure a 2 inch pipe, and the app says 2.1 inches, you need a way to adjust the setting to read 2.0 inches. Otherwise, when you measure a 3 inch pipe or any size pipe, the measurement would be off.
  • Calibration should be done with different sizes of pipe, to make sure you will get an accurate reading at any of those sizes.
  • The curvature of the pipe needs to be considered. You aren’t taking a picture of a 2D object. The pipe is 3D, so your camera may not see the top and bottom of the pipe as being 180 degrees away from each other. If you are too close to the pipe, you wouldn’t see the full 180 degrees. So your measurement would be too small.
  • Resolution of measuring. A pipe diameter tape measure normally has a resolution of 100th of an inch diameter. Can a smart phone app be that accurate?
  • The nearness of the object. For calibration, we would need some standard distance from the cell phone. Maybe this could be accomplished by using an object like a 12″ ruler, placed between the pipe and the phone. Hopefully, a less mechanical method will pop up.

If you know of an app that can accurately measure pipe diameter, please let me know. If one does not exist, I’m sure it will be invented in the near future.

Who Makes Diameter Tape Measures?

Lufkin Pipe Diameter Measuring Tape
Lufkin Pipe Diameter Measuring Tape

There are 4 main manufacturers of diameter tape measures.

  1. Lufkin® has a world-wide reputation for making high quality tape measures. They used to make them in the USA, but they have shifted the production facilities to Mexico. Some of the tapes are made out of a cast case, which is highly polished and chrome plated, like the w906pd. Others, like the w606pd have a stamped case, which is shiny and chrome plated.  A third type of case is black plastic, like the asw616pd. However, the tape blade inside is the same in all 3 types of cases. It is capable of measuring diameters up to 23 inches.
  2. Pi-Cobra is a brand name for diameter tapes made with

    Pi-Cobra Diameter Tape, Metric Pi-Cobra Diameter Tape, Metric

    a cast case which is chrome plated. It can hold a longer tape blade, capable of measuring diameters up to 38 inches. The case is very durable. These are manufactured in China.

  3. 24inch-od-tape
    24inch-od-tape

    Various other Chinese manufacturers make versatile OD tapes like the 416-04-024-P. The back side of the tape measures diameter up to 24″ in 100ths of an inch or 610 mm. The case is plastic, and has a key ring attached to it.

  4. The UT-56675 is made in the USA. It is capable of
    diameter-tapes-com
    diameter-tapes-com UT-56675

    measuring pipes up to 45 inches in diameter. This is a belt tape, not a pocket tape. The calibrations are in tenths of an inch diameter.