Customer Specifications - X-Ray over Gamma Ray Sources & AUT

Date 03-12-2010 13:41

What is your experience (or opinions) regarding the increase in customer specs for radiography requiring x-rays instead of gamma ray sources, as well as specifications requesting AUT? These subjects have been coming up more often in discussions with my colleagues in the pressure vessel industries. I'm certainly not narrow minded when it comes to things like AUT, but is the door really closing on gamma radiography? Do you think that conventional UT will soon be replaced by AUT?

~thirdeye~

By G.S.Crisi (****)

Date 03-12-2010 18:22

Back in my days of erector engineer, I was in charge of the construction of a natural gas compressing station in a remote location in Argentina, South America. Nearest civilization was 75 miles away. We had a 50 kW diesel generator to supply our electric power needs. If it failed, there wasn't another one as standby. After quitting hour the diesel generator was turned off, in order not to run it if not absolutely necessary.
There were two things that needed energy at night: the electrode storage oven and the welds ray inspection. For the first one, we made an oven heated with LPG (liquefied petroleum gas) which turned out to be a Practical Idea published on Power magazine.
The welds ray inspection was carried out at night so as not to interphere with the welding job. X ray inspection was unthinkable, for it required external electric power that wasn't avaliable at night. Only solution was to use gamma rays, that are energy self sufficient. The gamma rays equipment operator needed light, of course, and it was supplied by battery operated lanterns.
So you see, thirdeye, that there are circumstances where gamma rays are mandatory, whether someone likes it or not.
By the way, what does AUT mean?
Giovanni S. Crisi
Sao Paulo - Brazil

By fbrieden (***)

Date 03-12-2010 18:29

Automated Ultrasonic Testing

By thirdeye (***)

Date 03-13-2010 16:41

I wasn't actually thinking of this from a "practical use" point of view, in selecting one method over another.... I was wondering if there is a lack of confidence stirring with regards to gamma radiography.

This is my 35th year in the inspection industry, and like a lot of others I started with pipeline radiograhpy. We used both x-ray and gamma ray devices, both of which have definite advantages and disadvantages. I'll be the first to agree about the differences in quality of gamma ray negatives, especially with heavy wall thickness or cobalt sources verses iridium sources, but each technique's sensitivity is still monitored and the reliability of gamma radiogrphy has certainly been proven for many years.

~thirdeye~