This standard has been prepared under the direction of the Welding Standards Committee and is a revision of BS 2910 : 1973 which is withdrawn.
It is essential to quote the technique number in addition to the BS number whenever this standard is used.
Contrary to the 1973 edition, no distinction in technique is now made between ultra-fine-grain and fine-grain film and the two types of film have been combined using the technique number of the ultra-fine-grain film but descriptively 'ultra' Is no longer used. Although this has resulted in a reduced number of techniques, the original technique numbers have been retained.
The methods described in this standard are suitable for all types of application but no requirement is given as to when a particular technique should be used although guidance is given in a new appendix B. As so many factors affect the exposure time, minimum values have not been specified but are included as guidance. The extent of radiographic examination that should be applied and standards of acceptance are not specified as both of these aspects should be covered in the appropriate application standard or be agreed between the contracting parties.
This revision introduces ytterbium-169 and thulium-170 for the first time as gamma-ray sources, thus reducing the lower limit of thickness range covered by the standard to 2 mm for both X-rays and gamma-rays.
The explanatory information in appendix A has been retained to amplify and in some Instances to give the reasons underlying what is stated in the standard. Some principles and background to flaw sensitivity have been Introduced in a new appendix E.
Welds in some. pipe thicknesses can be examined with X-ray television fluoroscopic systems and although it has not yet seemed appropriate to produce a detailed standard for these new methods, this revised standard is not intended to preclude the use of such methods if the attainable sensitivity values are acceptable to the contracting parties.
It has been assumed in the drafting of this British Standard that the execution of its provisions is entrusted to appropriately qualified and experienced people.
