NDT of fillet and butt welds on structural steel

By Bioman Date 02-28-2018 13:36

I do not have all the details yet so I have to be carfeul with what I say. No one is blaming anyone either.

I am inheriting a mess created by inadequate project supervision and inadequate QA on a project which has already been in process for 3 years.

The previous QA never asked for or reviewed any qualifications (for welders and procedures) - I've requested them now. The project specs do require the subcontractor to work according to AISC A360 and AWS D1.1.

The entire issue started with the owner noticing really ugly welds that were made on HDG steel without removal of the zinc. We had issues where the pipe support slide and guide limiters welded to the structural steel broke off during pressure testing (weak welds were thought to be a contributing factor)

The grades of steel are European S235JR and S355JR, 10mm and up.

I will post more concise info as I receive it. We also have issues with incorrect high strength bolts and anchor bolts to concrete.

By 803056

Date 02-28-2018 15:14

Talk about a can of worms.

You are on the right track, asking for the welding documentation, i.e., WPSs and welder qualifications.

You can also ask for the contactor's QC reports. Without a doubt, they do not exist, but the contractor is responsible for their own QC. If there is evidence they have no QC program in place, it provides you with more latitude to take the steps necessary to ensure the work completed meets the requirements of the project specifications.

The best case for you is if the contractor cannot produce welding documentation that is correct or better yet, if not welding documents are produced. Again, it provides you with an opportunity to perform any necessary testing to ensure the work product of the contractor is up to standard.

A 25% reject rate on UT is very high, especially for connections deemed to be statically loaded. There are a couple of things you need to verify. First, is the person performing UT properly qualified and certified? What evidence is there that the person performing the UT is doing it correctly and he is evaluating the UT correctly? In short, make sure you have all your ducks in a row before pulling the trigger.

Best regards - Al

By Bioman Date 02-28-2018 15:46

Thanks for the reply Al.

The agency doing all the NDT- UT, MT, RT is government accredited, annually inspected and has the required qualifications for all personnel for all the requirements set forth in AWS D1.1, ASME PBVC IX & V and many others (as well as a good reputation in the industry). I am confident in their abilities and expertise.

The strucutral steel subcontractor has a QC program on paper - but its just on paper. I have not seen their CWI on site once - so how are the welds getting signed off......
The few WPS, PQR and WPQ's I have received thus far are a mess - they do not coincide, some qualifications were perfomed per ASME, etc.

I have asked the EOR to decide how much extra NDT they want since there is no guidance provided in code. They may ask for all field welds to be RT/UT'd - but its problematic because in the project doc's they never specified a figure for NDT, they were lazy and wrote "shall be per AWS D1.1".

By Maggs47 (**)

Date 02-28-2018 16:46

Bioman,

It sounds like you already know the answer to all your issues here. Just look at the tag line at the bottom of each of your posts. :wink:

By Lawrence (*****)

Date 03-03-2018 11:10 Edited 03-03-2018 11:18

As Brent mentioned AISC 360 Chapter N provides the amount of required UT based on two factors.

Factor 1 is sisemic catagory

Factor 2 is individual welder performance. Meaning; if any individual welder is performing at a 1st pass yield rate below 95%, it is required that 100% of their welds shall be UT tested until they teach a yield of 95% or better.

Factor 2 applies any time UT is required.

If you are in a sisemic catagory that required UT, a 75% agrigate pass rate I think would demand the welders receive 100% scrutiny until their performance improves.

You must consult AISC 360 Chapter N and verify via contracts, EOR and jurisdictional authority how Chapter N shall be applied to your project.

By Bioman Date 03-04-2018 20:15

Lawrence you are a genious, THANK YOU!!! :cool:

Found it in AISC A360 N5f - just as you said!

"Increase in Ultrasonic Testing Rate
For risk category II, where 10% of CJP groove welds loaded in transverse tension are tested, an increase in the rate of UT is required for individual welders who have failed to demonstrate a high level of skill, established as a failure rate of more than 5%, after a sufficient number of their welds have been tested. To implement this effectively, and not necessitate the retesting of welds previously deposited by a welder who has a high reject rate established after the 20 welds have been tested, it is suggested that at the start of the work, a higher rate of UT be performed on each welder’s completed welds."

We have no official identification of welders so as a first step we will mutiply the number of welders working by 20 and UT those to investigate the overall quality of all welds.

In parallel, the current structural and mechanical contractors are getting replaced and we are re-writting project specs and contract documents to ensure welders are qualified, consumables verified and all materials verified.

Once the repalcement contractors have been correctly vetted they will go back and repair the failed welds of the previous contractor.

Attachment: 20180228_120156.jpg (92k)