For example, to inspect new oil or gas pipelines, special film is taped over the weld around the outside of the pipe.A machine called a 'pipe crawler' carries a shielded radioactive source down the inside of the pipe to the position of the weld.The IAEA estimates that several hundred thousand such gauges are operating in industry worldwide.They measure the amount of radiation from a source which has been absorbed in materials.Radiotracers are also used in the oil and gas industry to help determine the extent of oil fields.Radioactive materials are used to inspect metal parts and the integrity of welds across a range of industries.
X-ray sets can be used when electric power is available and the object to be scanned can be taken to the X-ray source and radiographed.
Nucleonic gauges are also used in the coal industry.
The height of the coal in a hopper can be determined by placing high energy gamma sources at various heights along one side with focusing collimators directing beams across the load.
Density gauges are used where automatic control of a liquid, powder, or solid is important, for example as in detergent manufacture.
Radioisotope instruments have three advantages: There are two broad types of nucleonic gauges used in industry: fixed and portable.