TML
TML
(OP)
Recently an inspector (API 570 certified) told me that there's no need to place a tmL on the inside of radii of elbows. According to his opinion tml should only be placed on outdide radii of elbows.
He also mentioned that this criteria comes from a software that he's using.
any thoughts?
He also mentioned that this criteria comes from a software that he's using.
any thoughts?





RE: TML
What software is he using? what is his corrosion background?
I would stick to measuring both where you have access.
Good Luck
RE: TML
software I think is ultrapipe. I just finished reading API 570 and in 5.3.6.d) At any point of flow direction change, such as the inside and outside radii of elbows.
This is recommended where erosion/corrosion is expected.
His particular inspection plan does not include any tml on inside radii of elbows, only on outside.
Is it common practice just to UT outside radii of elbows?
RE: TML
Steve Jones
Materials & Corrosion Engineer
http://www.linkedin.com/pub/8/83b/b04
RE: TML
As Sjones puts it, if the damage expected is erosion (particulate's) go with the OD. I have seen corrosion on or just downstram of elbows on the inside radius of amine, steam condensate, produced water, and various others.
For a good monitoring program you should first define the damage expected. Treat each commodity / service as unique corrosion circuits / loops and assess the type(s) of damage expected.
From there you can build sound inspection plans.
Good Luck
RE: TML
During the initial data collection phase, we take readings completely around the pipe typically on 4 quadrants. After a corrosion rate is established, then we evaluate the revelance of the inside radius readings and through an RBI analysis, elect to maintain or delete this data recording point. Many different schools of thought out there on this one, but typically, the OD is thinner by nature of manufacturing. Bent pipe and other weird critters have as much as 18% thinning in the outside radius while the ID stays fairly constant. When in doubt, shoot a profile radiograph looking for sublte density changes in both planes.
The APIGUY....