Aquaculture Engineering

Types of Tapes - Steel Tape & Invar tape

Unit 1- Surveying

Chaining: Instruments used for chaining

Types of tapes:

Steel tape
Steel tapes vary in quality and accuracy of graduation, but even a poor steel tape is generally superior to a cloth or metallic tape for most of the linear measurements that are made in surveying. A steel tape consists of a light strip of width 6 to 10 mm and is more accurately graduated. Steel tapes are available in lengths of 1, 2, 10, 20, 30 and 50 m.

Invar tape
Invar tapes are used mainly for linear measurements of a very high degree of precision, such as measurement of base lines. The invar tape is made of alloy of nickel and steel, and has very low co-efficient of thermal expansion. Invar tapes and bands are more expensive. Invar tapes are normally 6 mm wide and are available in lengths of 20, 30 and 100 m.