A few days back, I attended a certification training in Industrial radiography along with some of my colleagues . Its somewhat similiar to clinical radiography. Doctors check for cracks in bones and position of internal organs, we check for defects like cracks, porosities, slag inclusions etc in welds. Both the parties need to interpret the radiographs, arrive at conclusions and take remedies. On both the cases, the equipments will be handled by trained technicians. One of the major differences in clinical and industrial radiography is that - apart from X rays, Gamma rays are also used for industrial purposes.
During our training, I asked the facilitators whether we can see the equipment if they have got one with them. They said no and gave a list of reasons like-its bulky, we dont have it here etc.. It never bothered me. The only practicals we need to do was the interpretation of radiographs and moreover I have seen the X-ray equipment during my final year B-tech project. There the radiography took place inside a darkroom which had thick lead and concrete walls and the controls were outside the room. It was ensured that no X-rays came out of the room by putting detectors outside.
The next day after my demand, the tutor came shouting " hey guys, equipment and operators have come , they will demonstrate". All of us went to the backyard to see it. There was a Maruti Omni parked and two men were standing near it. Both of them had similiar physical features, they looked somewhat tired,had sunken eyes and brown hair. They opened the back door of Omni and took out some equipments. " Hey this doesn't seem X-ray equipment" I told Ramzi. " It has got long tubes" he replied. "F**k man , its the Gamma ray source, stay out of it, come on we ll move" I said and we virtually dragged each other out of the place. I was shocked! The Gamma ray equipment never came even in my weirdest thoughts. I thought they brought the Xray equipment for demonstarating how the operators setup the current and voltage parameters.
Why did I run? There wasn't any danger unless they switched it on by cranking. The capsule was enclosed in a lead box which prevented the radiation from leaking. One of the operators had a detector to find out radiation leakage.But I know well that the Gamma ray sources are unpredictable and the radiation is invisible.The monsterous trefoil symbol (radiation warning symbol) on the equipment really frightened me.
Radiography using gamma rays is done usually in the night, when no other people are working nearby. But in fast track projects like the one which I worked last, it was even done during daytime, evacuating all the personnel working over there. We used to go to a base camp which was 2 km away from the site to avoid getting exposed. Though gamma ray radiography was used in our project, I never saw the equipment, infact I have seen it only in pictures.
But what about those guys who operate the equipment? Aren't they humans? Don't they have the right to live in this world without getting exposed to harmful radiations?
They do it for money. They get 5000-10000 Rs per month. Most of them are illiterate and are from financially poor background. They are mostly ignorant about the ill effects of radiation poisoning. There are standard safe practises which need to be followed, they should even use a protective apron and dosimeter, but in industry they neglect it.We had a chat with the operators about their experience with handling the equipment and its ill effects. They often get radioactive doses. Only after prolonged exposure, they will come to know that they got exposed. They feel dizziness,itching ,tendency to vomit etc. They either go to a physician and take some medicines(wont be of much use) or take refuge in alcohol . But knowingly or unknowingly they are killing themselves. On the other hand,they virtually save lots of lives-if they find cracks and defects present in the welds of pipelines and pressure vessels which would have caused gas or steam to leak and lead to explosion that would take 100s of lives.
Shouldn't the use of gamma rays be stopped ? It is a kind of non-destructive testing (NDT), but it is a destructive test as far as our mother nature is concerned. NDT techniques like ultrasonic testing can be supplemented to find the weld defects, I say much effectively using methods techniques like pulse echo method and TOFD (time of flight diffraction) method. This technique is being effectively implemented in offshore pipelay vessels(ships or barges that lay subsea pipelines ). Some of the codes and standards insist to go for 100% radiography for certain welds. The guys who write them never get exposed to harmful radiations and it will be the poor operators who will suffer. The codes and standards should be modified and the usage of gamma ray radiography should be stopped. Why should we still bank on a century old technique with hazardous effects when new techniques are available?
rather than stopping it ,if they have got some better clothes may be something resembles like an astranauts which prevents them from radiation. anyway if u check in foriegn countries they might be using it(there also it will happen naa).
ReplyDeletewhen the people who created standard say 100% test they might be thinking of 100s of lives in danger,if the weld fails. so no matter how it is ,factor of safety should be high
but if you have a better option for testing i will agree with you in changing the standards...
There are such clothes, infact Aprons and gloves.. but in our country, the operators never use.
ReplyDeleteIf you take the case of any code or standard used in the industry, it has almost remained the same for over 50 years. Somebody made it, then some others modify it lil bit, some addendums etc. But nobody dared to change the essence of them. Lots of new techniques has developed which can replace this technique.
for eg, let me elaborate the case of offshore pipelines. Hundreds of kms of pipeline have been laid under the sea.Each pipeline is made by joining individual 'line pipes'(usually 12.2m in length pipes). The vessels or ships used for pipelay lay around 3km of pipe per day on an average. That means 246 linepipes are joined by welding. Here in this case it is impossible to do radiography for all the 246 joints.A soon as the pipes are welded, the pipestring is laid into the sea. Here to ensure the quality of welds, we use ultrasonic testing. If the same code says RT is not required for offshore pipelay and 100% RT is required for some other jobs,does it make sense?
Now a days ultrasonic test is using world wide ..this Radiography test has been banned in all foreign countries.In reliance we have purchased ultrasonic equipments for testing. it has been widely used in our refinery Project. In our training session also we have raised the query 'Why ultrasonic testing is not using widely in india'.But they are saying in radiography minute cracks also can be identified and it can be repaired .
ReplyDeleteIn radiography, we can pick up even minute cracks, but cannot find the depth at which the defect lies.Whereas in the case of UT, we get the location as well as depth at which the defect occurs.
ReplyDelete