Dear Raghuram and CK, usage of Copper screens will further double the exposure time since the intensification factor of Cu is less. Coming to composite screens, it depends on the Code based on which the RT is being done. ASME allows only metallic screens to be used. There are no accelerators for development of films. Yes, there are linear accelerators and betatrons which produce high energy radiation interms of 4 to 12 MeV energy thus the exposure time being very less. As suggested, you may want to use Automatic film processor with developer temperature set at 28 to 30Deg.Celcius sothat the over all exposure time is reduced by 10 to 15%. In case of panoramic exposures of Circ.seams where the source is being kept at the centre of the shell section, pl.note that the shell thickness of 100mm also need to be considered as shielding for calculating cordon off distances thus the optimisation can be achieved in barricading the vicinity of radiation zone. I can suggest that during the circ.seam RT by panoramic technique, try to cover the adjacent long seams of either shells also thus in one exposure you are covering maximum weld. Do not forget to keep the IQIs at required positions as per the code requirements. thanks and regards, RPE
--- On Fri, 10/17/08, CKPurohit <ck@knm-group.com> wrote:
From: CKPurohit <ck@knm-group.com>
Subject: [MW:1218] RE: 1216] Re: How to reduce the exposure time for RT
To: materials-welding@googlegroups.com
Date: Friday, October 17, 2008, 5:34 PM
We are using 75 Ci source Co-60. Another thing is vessel can not kept in enclosure and barricading area will be too large if we combine the source. We are using the fast films. I want to know on this accelerators for developing…. If somebody have some info pl come up… Regards. CK From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of raghavendra pemmaraju
Sent: Khamis, 16 Okt 08 11:35 pm
To: materials-welding@googlegroups.com
Subject: [MW:1216] Re: How to reduce the exposure time for RT you can use combination of two sources together ( unsharpness is not an issue since the thickness is 100mm and SFD 2m) this will increase the Curie strength of the source. Also while developing you may increase the Temperature of the developer to 2 deg.C sothat an imporvement of 0.2 H&D of optical density can be had, proportionately you can reduce the exposure time. When you use Combination of films ( double film with minimum optical density of 1.3H&D per film), you are in tern effectively reducing the exposure time by 40% when compared to that of a single film with 2.0H&D optical density. you can even try to use high speed films such as AGFA D8 provided you are achieving the required sensitivity. This will reduce further 30% of exposure time. Try the above remedies, all the best ! RPE
--- On Thu, 10/16/08, CKPurohit <ck@knm-group.com> wrote: From: CKPurohit <ck@knm-group.com>
Subject: [MW:1215] How to reduce the exposure time for RT
To: materials-welding@googlegroups.com
Date: Thursday, October 16, 2008, 7:04 PM I need help to find out how to reduce the exposure time for heavy wall thickness RT (above 4" thickness and ID of vessels 4 meter) . Composite film is one of the option. Any other idea ? I heard from my client that there are accelerators available which can be used for developing the film to compensate the reduce time of exposure. We are using Co-60. Regards. CK
***DISCLAIMER NOTICE ***
"This e-mail and any files transmitted with it is confidential and is intended only for the use of the recepient(s) named above.
If you are not the intended recipient, any review, retransmission, dissemination, distribution, printing, copying or use the information contained in this message or any part thereof in other manner is strictly prohibited.
If you receive this e-mail in error, please notify the sender immediately by return e-mail and delete the e-mail and any of its attachments.
Any personal views or opinions expressed by the sender shall be understood as neither given nor endorsed by KNM or any of the companies within the Group."
|
***DISCLAIMER NOTICE ***
"This e-mail and any files transmitted with it is confidential and is intended only for the use of the recepient(s) named above.
If you are not the intended recipient, any review, retransmission, dissemination, distribution, printing, copying or use the information contained in this message or any part thereof in other manner is strictly prohibited.
If you receive this e-mail in error, please notify the sender immediately by return e-mail and delete the e-mail and any of its attachments.
Any personal views or opinions expressed by the sender shall be understood as neither given nor endorsed by KNM or any of the companies within the Group."
|
__________________________________________________
Do You Yahoo!?
Tired of spam? Yahoo! Mail has the best spam protection around
http://mail.yahoo.com
--~--~---------~--~----~------------~-------~--~----~
To post to this group, send email to materials-welding@googlegroups.com
To unsubscribe from this group, send email to materials-welding-unsubscribe@googlegroups.com
For more options, visit this group's bolg at http://materials-welding.blogspot.com/
The views expressed/exchnaged in this group are members personel views and meant for educational purposes only, Users must take their own decisions w.r.t. applicable code/standard/contract documents.
-~----------~----~----~----~------~----~------~--~---
No comments:
Post a Comment