The United States never did switch over to the metric system, as it was planned in the 1960’s and 1970’s. Yes, metric went over like a lead balloon. Americans are happy with inches, feet, gallons, and yards. The centimeter, liter and meter were mostly rejected. Both systems are used today in 2021 in labeling food products and liquids, but we Americans have learned to skim over those parts of the label that don’t fit into our familiar system.
The scientific community is firmly based on the MKS and CGS systems (meter, kilogram, second) and (centimeter, gram, second). The biggest part of the world is metric-based also.
Fortunately, pipe diameter tape measures are made for both systems, separately, and there is even one that is made with the inch and metric system together. The front side of the tape is in diameter inches (up to 38). The back side is in diameter millimeters (up to 955). This is a rare tool, but some companies need both measurements to satisfy their requirements.
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.
Pi-Cobra is a brand name for diameter tapes made with
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.
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.
The UT-56675 is made in the USA. It is capable of
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.
The popular Barlow Chrome Tape Measure number 20217. Why this product? The Barlow tape is a household word in many USA homes. The Barlow brand has a proud history of quality. Simplicity in design makes for a long lasting product life. The dual scale, metric and inch, make it popular in any country. The smooth compact design makes it a great tape to keep in your pocket. Your company logo can easily be laser engraved on the front and back.
64ths or 100ths? This question applies only if you need the Inch version of a pipe diameter tape. If you are in the oil and gas industry, you probably prefer the 100ths calibration. If you are in the boat or automotive industries in the USA, you would probably prefer the 64ths of an inch calibration. If the SKU number has a “d” in it, this means it is calibrated in 100ths of an inch.
Size. The Lufkin models of the pocket diameter tapes will measure pipe diameters up to 23 inches. The Pi-Cobra models will measure pipe diameters up to 38 inches.
Lufkin is a name you can trust. They know how to make an accurate pocket tape measure. An when it comes down to a detail, like putting a wider space between the zero mark and the next mark, they do it right. That extra space accounts for the thickness of the tape. The resolution is 100th of an inch diameter. It comes in a durable chrome-plated metal case. A company logo is imprinted on the front, and protected by a clear overlay. This is the best choice for a pipe diameter tape measure.