xray limitations

By swsweld (****)

Date 11-03-2009 03:14

The RT techs that shot our pipe required at least 12" of radial clearance to make the shot. Most of the pipe was about 5' deep so the trench walls and the spoils created the radiation boundaries with proper oversight. They placed cones in the ditch and we cleared out beyond the cones when the source was exposed. Schedule 40 shots were less than 10 seconds each if memory is correct so not too much down time due to xray's. Two to three shots per pipe. 2 1/2"-14" were typical sizes.

Just last week we were informed that we did not get a 3 Million dollar underground job in our back yard. Maybe it should have been 2.5 million. haha
In this recession contractors are bidding work to break even...at best.

Good luck with the bid. Hope you get it.

By PipeIt

Date 11-03-2009 11:52

Thanks

Did they drag the pill down the pipe and how far did they drag it?

I have never really seen them shoot our spools but I thought they need something inside the pipe to get the proper shot and I think they call the inside portion the pill.

By swsweld (****)

Date 11-04-2009 03:48

We were only required to shoot 10% so the pill box was carried from weld to weld (welds picked randomly by the Army Corp of Eng.)

There is no need for an RT port on the pipes. They shot thru wall and elliptical shots on the smaller pipe sizes. The film was wrapped on the O D of the weld (bungee cord) and the source is located adjacent to the weld. It is on the outside of the pipe.

On some pipes and spools they install a RT port near the weld and the source will inter the ID of the pipe and expose all of the film that is located on the OD of the pipe weld, in one shot. This is not mandatory but it is a common technique. I better shut up now. I've probably used wrong terminology and wrong descriptions as I have never shot welds just been around it a little. There are experts in here that can give better descriptions.

By CWI555

Date 11-05-2009 12:37

By PipeIt

Date 11-05-2009 13:01

Nice detail the optional source would most likely apply to long runs of underground pipe where its not practical to have the film or source inside due to the long runs?

By CWI555

Date 11-05-2009 16:58

You can shoot it through wall if your total double wall T is less than the effective range of the source. (source outside, film opposite and outside)
You keep mentioning underground pipe, by underground pipe you don't mean buried do you?

By PipeIt

Date 11-06-2009 12:22

Yes buried, the carrier pipe is carrying diesel and then there will be a casement pipe around the carrier pipe.

We would only be required to X ray the carrier pipe schedule 40, 304 stainless.

Thanks

By CWI555

Date 11-06-2009 16:09

You have to have access to this pipe to get it shot. I would also advise the following:

*That you look closely at the governing codes being that it's diesel.

*Pay attention to your spec, and looking into the grade of material being used.

*Look into the need for bitumen protection, this should be in conjunction with the assessment of the concrete encasement as well. In short, you need a corrosion analysis. I suspect you'll find this is a big one. If your specs don't have it covered, I suggest you get it covered as you don't want to be digging this up in 5 years on your dime.

Getting it radiographed before it goes into the ground will be the easy part.

Regards,
Gerald

By PipeIt

Date 11-06-2009 20:06

Wow thanks for the heads up.