What is the selection criteria when choosing between Class 1 and Class 3

[razana74]

Hello members,
What governs the selection between Class 1 and Class 2 RT film? I've looked into ASME V and it only specify that industrial radiography film be used. It also specifies the density requirements etc. How do we choose between these two film classes and determine whether its suitable for our project? (Usage : Hydrocarbon column for petrocemical plant)

 

[Goahead]

In the classic Kodak's "Radiography in Modern Industry",
downloadable from

http://www.kodak.com/eknec/documents/87/0900688a802b3c87/Radiography-in-Modern-Industry.pdf

Class 1 and Class 2 RT films were not found.

Another Document:
Radiographic Testing - A comparison of Standards for Classical and Digital Industrial Radiology

http://www.ndt.net/article/wcndt00/papers/idn324/idn324.htm

mentions:
The radiographic techniques are subdivided in Europe into two classes:

Class A: basic technique;
Class B: improved technique.



Regards,

http://www.welding-advisers.com/

 

[doct9960]

razana74,

Reading the Appendix in ASTM E 1815 (Standard Test Method for Classification of Film Systems for Industrial Radiography), it says there that Class/Types 1, 2 or 3 were film types based on a version of ASTM E 94 dated before 1984. In ASTM E 94-83, films were classified (in a SUBJECTIVE way) in order of increasing speed and decreasing image quality (contrast & graininess)...
Film Type 1: low speed; very high contrast; very low graininess
Film Type 2: medium speed; high contrast; low graininess
Film Type 3: high speed; medium contrast; high graininess

ASTM E 1815, on the otherhand, classifies films based on image quality performance based on four MEASURABLE image quality parameters. Speed is not a classification parameter.

I suggest you read ASTM E 1815 for more information.