Tiêu đề CEP233 - M4 - The Taping Party.pdf ✅

4 of 12 CEP233 | FUNDAMENTALS OF SURVEYING meters long to make a figure 8. Steel tapes are designed for most conventional measurements in surveying and engineering work. 2. Metallic Tape Metallic tapes are sometimes called woven tapes. They are made of water- proof linen fabric into which are woven longitudinally small brass, copper, or bronze wires to increase its strength and reduce stretching. Metallic tapes are usually 30 or 50 meters long, 10 to 15 mm wide, and come in enclosed reels. It is used principally for measuring short distances in locating details for maps, earthwork cross sectioning, and for other measurements where a light and flexible tape is desirable. This type of tape is unsuitable for precise measurements and should not be used around electrical installations. 3. Non-Metallic Tape Non-Metallic Tape is a type of tape woven from selected synthetic materials with strong dimensional stability. The tape is in turn coated with a plastic material to reduce the effects of moisture, humidity, and abrasion. Non- metallic tapes are safe to use when working around electrical installations or for any type of work where a metallic tape would be suitable. 4. Invar Tape A special tape made of an alloy of nickel (35%) and steel (65%) with a very low coefficient of thermal expansion (1/30 to 1/60 that of a steel tape). Its name was derived from the word “invariable” since it is less affected by temperature changes than in a steel tape. Invar tapes are used only for precise measurements in geodetic work and for checking the length of other kinds of tape. They are about ten times as expensive as ordinary steel tapes. The use of invar tapes will require very careful handling since the alloy is soft and somewhat unstable. It is a kind of tape which gets easily bent and damaged. 5. Lovar Tape The newer type of measuring tape which has properties and costs somewhere between those of conventional steel tapes and the invar tape. 6. Fiberglass Tape This tape is made by weaving fiberglass in a longitudinal and transverse pattern. They are strong and flexible and will not shrink or stretch appreciably with changes in temperature and humidity. A fiberglass tape is best suited for use in the vicinity of electrical equipment. 7. Wires Before thin flat steel tapes were produced, wires were utilized in measuring lengths. They are still practical to use in special cases as in hydrographic surveys. 8. Builder’s Tape Are tapes having smaller cross sections and are lighter in weight than the engineer’s tape. Such tapes are graduated to suit commonly used dimensions in building construction. 9. Phosphor-Bronze Tape A rust-proof tape designed for use in the vicinity of salt water. 10. Nylon-coated Steel Tape Is a flexible crack-resistant steel core tape with a coating of permanently bonded non-conducting nylon. It is designed to be resistant to corrosion and is immune to rust. 4.5 Taping Accessories