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Non destructive testing selection for different damage mechanisms

Non destructive testing selection for different damage mechanisms

Non destructive testing selection for different damage mechanisms

Hello all,

I work as an inspection engineer on a very large LNG facility where a risk based inspection exercise has been partially completed. We have circuitized the facility, identified the damage mechanisms and determined inspection intervals. Unfortunately the writing of inspection workscopes and placement of CML's was bypassed and now we are 2-years into operation with only single line work orders in a CMMS to instruct us that an inspection is due.

I am severely resource constrained but have now been granted approval to hire some inspection engineers to execute the workscoping activities. For consistency I want to develop a procedure which outlines the NDT techniques that should be specified for different damage mechanisms identified in the RBI. For example, bottom of line CO2 corrosion use a UT scan or profile RT depending on the pipe diameter.

I have seen basic guidance in API 577 on NDT detection technique for weld defects and there is some low level guidance in the book Practical Non-destructive testing but nothing solid that I would reference in my procedure.

Basically I need a guide which lists the potential damage mechanisms in O&G and gives the suitable NDT technique
Chloride SCC (SS)
Chloride Pitting (SS)
Deaerator Cracking

RE: Non destructive testing selection for different damage mechanisms

You need to translate the mechanism (ie pitting) into a indication that you would be looking for (localized wall perforation). Then you can start matching up techniques.
Since many will be size and alloy dependent you are going to have a large matrix to work through.
I have read an ASME document that rates NDT methods vs indication types, I'll look for it for you.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

RE: Non destructive testing selection for different damage mechanisms

I'm not aware of any publicly available document that marries the two requirements together, not least because of the myriad services and equipment configurations. API RP 571 will give you the damage mechanisms. If it is an upstream facility, you can supplement the API document with http://publishing.energyinst.org/topics/asset-inte.... For vessels and static equipment, DNV-RP-G103 provides some useful inspection guidance. Essentially, you have to give your Level 3 a grounding in corrosion morphology, identify the specific inspection locations for them (determined by your RBI exercise), and let them write the necessary specific NDT procedures.

Steve Jones
Corrosion Management Consultant


All answers are personal opinions only and are in no way connected with any employer.

RE: Non destructive testing selection for different damage mechanisms

@EdStainless thanks for your reply let me know if you find that document

@SJones thanks also for your reply, im aware of API 571 and could use it for building a document from scratch, along with several other documents that are out there, but it doesn't summarise NDT/damage which im after to save time. The linked document requires an energy institute account which I don't have unfortunately. I have seen the DNC document before, it is very nice, particularly table A-1 and A-2 which I will use.

Any other ideas please let me know... a good high quality document like the one im planning takes a solid 1-2 months to complete so any summarised info I can use will help to reduce this

RE: Non destructive testing selection for different damage mechanisms

I'd take a peek at Annex 2.C in API 581. Inspection Effectiveness Tables for Risk Based Inspection...

Gives you tables listing (for instance)

Inspection Category~~~~~~Intrusive~~~~~~~~~~~~~~~~~Non-Intrusive
Highly effective:~~~~~~~~100% PT w/ UT follow-up~~~~~~N/A
Usually effective:~~~~~~~65% PT w/ UT follow-up~~~~~~~100% AUT OR ...

Similar tables exist for many damage mechanisms and damage morphologies. Should be a good jumping off point.

Nathan Brink

RE: Non destructive testing selection for different damage mechanisms

Ok, I had to register on this site to see if I could assist you. Actually saw the link on linkedin

1. Have you seen API 574 for piping?
2. Can you outline the Corrosion loops/circuits that were developed during the RBI studies? or You can email me austine.isodje@gmail.com for further discussions.

RE: Non destructive testing selection for different damage mechanisms

I do this frequently. You also have to have some experience with ndt techniques and their limitations. Some techniques don't find certain types of damage well so we would use something else, let me know if you have not solved this issue.


RE: Non destructive testing selection for different damage mechanisms

Might find this useful...

ASTM has tried to automate the process of determining/monitoring stress-critical areas in boilers and piping systems…

Introducing easy and seamless online access to critical stress tables in Section II, Part D of ASME Boiler and Pressure Vessel Code.

For engineers involved in the design, construction and operation of boilers, pressure vessels and related equipment, the stress tables in Section II, Part D of the ASME Boiler and Pressure Vessel Code are a critical technical reference. These engineers rely on the stress tables to help them select the appropriate grades of materials to meet the code’s specific requirements for material strength and temperature limits.

Traditionally engineers have relied on hard copies of the Code, referencing the stress tables spread across hundreds of pages within the voluminous Section II-D. However, using the paper-based tables is tedious, time-consuming and fraught with the potential for transcription errors or misread figures –creating additional costs and risks for companies that rely on the Boiler Code.

Now engineers have a fast, easy way to access this essential resource through the ASME BPVC Electronic Stress Tables powered by IHS.
… …

Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

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