Quantify Defects For WPT IAW QW-453

[tc7]

For welder performance qualification on "hard-facing overlay", QW-453 Note(8)(page 145 of Section IX 2007 edition) requires sectioning, macroetch and 5x visual examination of both surfaces. Inspection is for " cracks in base metal and HAZ, lack of fusion, or other linear defects"

How/where can I get a better definition of "other linear defects"? What about porosities? There must be a other guidelines that quantify linear indication size or clusters and other pass/fial criteria.

I'd also like to perfrom a cursory hardness checks on the welders test plates. QW-453 Note (7) says to take three hardness readings from locations shown in QW-462.5(e)(page 165 of Section IX 2007 edition) for plate coupons, but this figure is not revealing any location information. Can anyone clarify this please?

Thansk for any help.

 

[weldtek]

tc7,
Bear in mind that the requirements in Sec IX are minimum. You, or your customer, may have more stringent criteria that must be met in order to qualify. Note the reference in both notes 8 & 10 to the 'requirements specified in the WPS'.
As to hardness tests, you take these where you want, but, they become your qualified thickness. In other words, let's say you need 37 Rc min. You take the hardness at 3/16" from the interface and you get 39 Rc, which is ok. Based on theses tests, your minimum qualified finished deposit thickness is 3/16". If you decide you'd rather put 1/8" deposit down, you need to retest. Makes sense don't you think?

 

[tc7]

Thanks weldtek-
WPS' don't usually address allowable defects or any defect criteria or chemical composition (except by reference to the steel specifications or the filler specifications).

Our typical steam valve production hardfacing application varies between .050 -.070" thick (final finished thickness), depending on the particular valve. So should hardness measurements be taken in that thickness range? we have been requiring the welders to apply two layers at 1/8" each and then taking hardness measurements after milling the double layer down to about 3/8"?
Also have been requiring the production base metal to be used for WPT's because this will affect the hardness measurements. Is this required?

 

[weldtek]

tc7,
I must apologize because in my previous post I mixed up rules for procedure qualification with those for performance qualification.
Actually hardness tests are not required as part of operator performance qualification per Sec IX. My previous comment regarding hardness testing applies only to procedure qualification. If you review the requirements outlined in QW 453, only notes 8 & 10 apply to performance qualification.
Like you, I don't normally specify acceptance criteria in the WPS. I do however, stipulate the minimum required deposit thickness for both CRWMO and HFWMO.
Your practice of using production base metal for testing isn't a bad one but Sec IX does allow for materials of the same P #.
It sounds as though you are being more conservative than Code mandates, but, that isn't necessarily a bad thing.
My opinion.