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Up Topic Welding Industry / General Welding Discussion / Is there a standard procedure for grinding welds flush?
- - By OldMan Date 11-21-2019 21:45
Hello, is there a standard procedure for grinding butt welds ground flush that is specified for girder fabrication? I know the general rule is to grind in the direction of applied stress and usually ground flush is a requirement in the tension side of the web or flange welds but I cannot seem to find a procedure in terms of what type of grinder or discs are used and whether there are any specific requirements for surface roughness? Do large fabricators have an automatic grinding machine or do they usually do it by hand?
Parent - - By jwright650 (*****) Date 11-21-2019 22:49
I think it is in the code of standard practice. They give a roughness specification.
Parent - - By OldMan Date 11-22-2019 17:46
Thank you! I must have missed it; Section 6.2.2 of the AISC 303 talks about surfaces that are specified as "finished", roughness height (Rp - max peak height value?) should be less than or equal to 0.5 mils (12.7 microns) and it also mentions use any fabrication technique to achieve this. Therefore, using a regular old grinder with various discs that will give me a smooth texture should be permitted.

Anyone else that has been around large girder fabricators know if they just use a regular grinder or if they have some sort of automatic robot grinder for deburring and ground flushing accessible welds?
Parent - - By jwright650 (*****) Date 11-22-2019 22:05
I was the QC at a fabricator for just shy of 30 years and we always ground the reinforcement down flush with a regular grinding wheel and the used a flap disc if we needed it smooth due to shiny paint or AESS situations.
Parent - - By 803056 (*****) Date 11-23-2019 00:12
I think NACE has a standard and plastic weld replica of different levels of finish in preparation for coating.

Al
Parent - - By jwright650 (*****) Date 11-23-2019 12:34
Yes Al, NACE does....they were quite expensive.  Surface roughness comparator,  they also have surface preparation pictorials for the different levels of surface preparation prior to applying a coating. SP2,SP3, SP6, SP7,&SP10 were the common ones that we used.
Parent - - By 803056 (*****) Date 11-23-2019 15:09
I think we might be thinking of two different standards. The one I'm think of was a plastic replica with welds in the "as welded" condition, "as ground", "as sanded", to almost polished. It was different that the standard that deals with cleans from a quick "brooming" to various levels of grit blasting of cleaning for the purpose of painting.

If I get a chance, I'll see if I can still find it.

Al
Parent - - By jwright650 (*****) Date 11-24-2019 02:29
Yes, two standards. One came with an optical comparator that looked like a flashlight with a magnifying glass and a series of standard finishes that you could compare to your material.  The other as you stated, was for comparing the cleaning and blasting profiles.
Parent - - By 803056 (*****) Date 11-24-2019 15:03
No, we're still talking two different things. The sample I'm talking about was a series of welds finished to different degrees of grinding and finishing. It had nothing to do with grit blasting.

Al
Parent - - By jwright650 (*****) Date 11-24-2019 22:54
The cleaning or blasting samples are different.  We also had samples with different roughness finishes by several methods of finishing. Ie. Grinding, milling, gouging, cutting,  etc. They weren't welds perse', but blank pieces with different roughness finishes in each method of removing material.
Parent - By 803056 (*****) Date 11-24-2019 23:26
I've got a sample like the one you described, it shows different surface produced by different machining methods. They are available from several sources. I may have purchased mine from Grainger or MSC.

Al
Up Topic Welding Industry / General Welding Discussion / Is there a standard procedure for grinding welds flush?

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