QW-403.6 1

[tekari123]

Dear All,

What is the difference between QW-403.6 (T Limits) & QW-403.8 (Change in T qualified)..? How is both different from each other

KiNdly help.

Alok

 

[SectionIX]

Alok

QW 403.8 is the standard thick range shown in Table 451.1.

QW 403.6 only applies if supplementary essential variables apply. When this is the case, the minimum qualified thickness alone is at issue:

For example, if you qualify on 3/4" plate, your WPS qualification range would be 3/16" to 1.5" provided supplemental essential variables do not apply.

Using the same example, and if supplemental essential variables do apply, your WPS range would be 5/8" to 1.5".


QW 401.3
When essential variables are qualified by one or more PQRs and supplementary essential variables are qualified
by other PQRs, the ranges of essential variables established by the former PQRs are only affected by the latter
to the extent specified in the applicable supplementary essential variable (e.g., essential variable QW-403.8 governs
the minimum and maximum thickness of base metal qualified. When supplementary essential variable QW-403.6
applies, it modifies only the minimum thickness qualified, not the maximum).

QW 403.6
The minimum base metal thickness qualified is the thickness of the test coupon T or 5/8 in. (16 mm), whichever is less. However, where T is less than 1/4 in. (6 mm), the minimum thickness qualified is 1/2T. This variable does not apply when a WPS is qualified with a PWHT above the upper transformation temperature or when an austenitic or P-No. 10H material is solution annealed after welding.

 

[jwhit]

I've just gone through this, and in fact queried some of the requirement on this forum. Section IX is correct in what he is telling you.
Pay particular attention to the "less than" statement regarding 1/4"T. I couldn't seem to wrap my head around that limitation until a couple of forum members straightened me out. As a result I am qualifying plates at 3/16", 3/8" and 1.5" to cover all the thicknesses encountered in production. Some of my "superiors" aren't happy about the number of PQR's it will take to have legit procedures, but, for the first time ever, our procedures will be per the code. The point is, that there are some very knowledgeable people here who will gladly point you in the right direction.