Welding Position Qualified AWS D1.1, Table 4.1 vs Table 4.6

[laurudolphy]

Dear friends,

Table 4.6 point 6
A change in position to vertical up. A 3G vertical up test qualifies for all positions and vertical down.

The above point mentions that 3G Vertical up qualifies for all positions, when CVN requirements are called for when qualifying a WPS.

Table 4.1
When test is conducted on a 3G position, the position qualified is only VERTICAL and not ALL or even Flat or Horizontal, as per 4.6 point 6 above.

May I request to know, why this difference is position qualified between Table 4.1 and 4.6,

Thanks in advance

[wefel]

Table 4.6 is not a standalone list of variables. Even when qualifying WPS for CVN (charpy v-notch) testing applications you must take into consideration the par. 4.36.3 that states that the WPS shall conform to the limits of table 4.1 (positions qualified), 4.2 (diameter/thickness range qualified) and 4.5 (PQR essential variables) plus those supplementary essential variables applicable only to CVN testing (table 4.6).

Being more specific, even though Table 4.1 specifies that welding on 3G position qualifies vertical position, by the Table 4.5, point 30, it is made clear that a change in vertical welding is an essential variable and thus (as clarified by the code) a WPS qualified in the vertical uphill direction is not qualified for vertical downhill direction and vice versa.

Table 4.6 includes additional requirements that supplement the essential variables listed in table 4.5. As far as the point 6 of Table 4.6 is concerned, it doesn't mean that the WPS qualified on vertical-up position qualifies for vertical-down position (table 4.5, point 30), instead it means that a WPS qualified on vertical-up position qualifies for vertical-down position and for all other positions only with respect to CVN testing requirements (e.g. if a manufacturer requires to qualify two procedures that, with respect to the essential variables, vary only to position, one using vertical-up position and another one using vertical-down position, CVN testing shall be performed only for the procedure qualified using vertical-up position).

Please have a look at AWS D1.1, Commentary on Structural Welding Code-Steel, par. C-4.8 that clarifies this issue.

From a metallurgical point of view, downhill progression needs high travel speed to stay ahead of the molten weld puddle as well as it employs string beads, instead the uphill progression employs slower travel speed and may use a wide bead technique. Assuming all other variables are held constant, the lower speed of uphill progression produces higher heat input that results in grain coarsening and thus worse notch toughness. So, a procedure successfully qualified using uphill progression would provide better notch toughness using downhill progression.

[laurudolphy]

Thanks Wefel,

From what I understand from your comments,
Material, thickness remaining constant,
If I qualify a procedure for 3 g position, the position qualified would still be Vertical only.
and in order to weld in 1 G position I have to qualify another test piece.

But if there is a CVN requirement, then I do not have to do CVN testing on the 3G coupon as well as the 1G coupon, instead doing CVN Test on the 3G coupon would suffice and this report can be used on both the WPS (1G and 3G), provided that the 3G coupon was welded in vertical-up progression. Am I understood your reply well?

Thanks mate.

Would you mind looking at another post of mine regarding welding of ST 52 / S355J2H pipe to EH36

[wefel]

But if there is a CVN requirement, then I do not have to do CVN testing on the 3G coupon as well as the 1G coupon, instead doing CVN Test on the 3G coupon would suffice and this report can be used on both the WPS (1G and 3G), provided that the 3G coupon was welded in vertical-up progression

I don't agree with this statement since it doesn't clarify what about the PQR, essential variables, etc.

Lets give an example so as this issue to be more clear:
Consider that you have a PQR qualified for all positions and based on this PQR you need to prepare three different WPS for welding in three different positions, flat, vertical-up and vertical-down with equal CVN testing requirements for all these three weldings. In such a case, you don't need to prepare three test specimens for the performance of impact test, instead you need to prepare only one test specimen using vertical-up position.

[Ballbearing]

wefel,
That is exactly what he has said - it appears english may not be the first language of laurudolphy but I understood what he was saying.
Cheers,
BB

[laurudolphy]

Thanks Wefel and Ballbearing.

Thanks for making an effort to understand what I was saying or asking.

To clarify what Wefel has said,

Consider that you have a PQR qualified for all positions and based on this PQR you need to prepare three different WPS for welding in three different positions, flat, vertical-up and vertical-down with equal CVN testing requirements for all these three weldings. In such a case, you don't need to prepare three test specimens for the performance of impact test, instead you need to prepare only one test specimen using vertical-up position

How can I have a PQR for all positions? Is it possible to have such a PQR unless it is a pipe coupon welded on 6G position.
I am of the understanding that due to the position restrictions, and to generate a WPS for all position for plate, (including downward progression), I would have to create 4 coupons, 1G, 2G, 3G Vertical up and 3G Vertical Down maintaining all other essential variables.
Clubbing all these 4 PQR's I would generate 1 WPS which would qualify me to weld a plate in ALL Positions. And to qualify this WPS with CVN, i will do a test only on the 3G vertical position coupon. And this would qualify me to use this WPS for ALL Positions where the owner asks for CVN requirement.

Have I understood or misunderstood.
Thanks mate for bearing with me with my english.

[Ballbearing]

Rudolf,
You were pretty close.
You do not have to do a 1G if you perform the 2G - you get the 1G for free. LOL !
2G, 3G VU and 4G will give you three x PQRs.
Perform impacts on the 3G VU coupon and then you can write two x WPS - 1 x all positional welding with impacts and 1 x all positional welding without impacts.
Hope that helps
Regards,
BB

[laurudolphy]

Thanks Ballbearing for the confirmation.
Regards
Rudolf