By CWI555 
Date 08-21-2007 05:36
Edited 08-22-2007 03:39
( I don't know the specific specification of the pipe your using so I'll speak in general terms, please ignore this information if you already know it ).
Piping specs usually consist of a specific specification with data that only applies to that specification such as ASTM 312, and then a general specification such as ASTM A999.
Specifics on the pipe would be needed to pin down the answer in regards to out of round tolerance.
Usually the requirements for ovality will be found in the referenced general spec. However; when that pipe comes out of the manufacture, they typically only measure the ends for ovality as it's not very practical to do so for the entire length. It's also very hard to sell ovality concerns after you've cut it. If your going to push that issue, then you will likely have to do it before you make any cuts.
As for reading the film:
B31.1 (only have 99 version so please verify current status) will kick back to section V, 04:Section V article 2 and the referenced documents therein will tell you the following:
T233.1 image quality indicator design/SE 1025 hole type and SE 747 wire type
T282.1 and .2 define density requirements. This has specific application to your needs. Some RT companies screw up this part as they miss this particular requirement.
T282.1 gives the general density requirements dependant on a few variables its typically between 2.0 and 4.0 transmitted.
T282.2 states +15 or - 30 percent variation. Herein is the typical screw up if there is one. This percentage not only applies to hole type IQI but also the wire type.
For the wire type, density is as measure adjacent to the required wire.
Depending on the temperature service reinforcement is allowed up to 3/16" for nominal wall thickness .438" (for 14" sch 40).
This becomes important as using a little reinforcement kicks you up to a B set and a required wire 7. The little bit of difference isn't going to mean a hell of a lot for shot time or anything else. (Use fastest film you can and still see the required wire. This also is another reason for a 6 vs a 7 wire., it gives you a little more latitude which is needed with hilo.)
Putting that together, the wire will be source side over the weld, and when you run into the varying densities inherent in hi lo, the wire will cover all density ranges
(assuming within 2.0 and 4.0).
Having the film quality meeting the code you go to interpretation. Assuming the weld is within code otherwise, the hilo can be read. the biggest problem there can be found in inexperienced interpreters. The sharp transition in density's can make a line appear where there is none. (slang term; Mock banding)
For hi lo conditions this is often misinterpreted as either root LOF or Lack of pen. To assess whether or not it's real, simply laying an opaque object such as a blacked piece of scrap film with a straight line just under the perceived line will make it go away. If it is real it will remain. Many, many moons ago (20 years) when the ink wasn't dry on the new LII cert, I feel into that trap and was shown the errors of my ways. After that, it's been no problem. It comes down to experience. For me, as well as any experienced interpreter, reading that film should be no problem, therefore bad RT's should never come into the picture unless its an actual flaw created by welding.
Regards,
Gerald
not selling or advocating just showing an example- backing rings are the same as backin plate for groove weld in pipe and tubing applications -not good in all place like if you have concerns of impeding flow they might be objectionable but the are usefull for alignment and some have tab for root spacers on'em.
