QW453 3

[mirhosseini]

In ASME Sec IX, QW 453, note 1, we read:
"for processe depositing a weld bead width greater than 1/2 in. wide, the weld overlay shall consist of a minimum of three weld beads in the first layer"

My questions:
1-How many layers shall be welded in corrosion resistance overlay? for example it can be welded 2,3 or more layers?

2-We can find 'T' or qualified range of thickness of test coupon but there is nothing about 't' or qualified range of diposite weld metal. it means that qualified range of diposite weld metal is according to QW 451?

Regards
H.Mirhosseini

 

[metengr]

The following are answers to your questions, based on my interpretation of QW-453 using the 2001 Edition/2003 Addendum of the ASME B&PV code - Section IX;

1. To qualify a procedure for corrosion resistant weld overlay, the welder must deposit a minimum 1.5" wide X 6" long pad of weld overlay on a test coupon using the guidelines/notes in QW-453. For performance testing, the welder must deposit a minimum 1/2" wide weld overlay consisting of a minimum of 3 weld beads in the first layer. This is done to achieve the necessary dilution with the base metal. There is no limit on the maximum number of layers for the weld overlay (see below).

2. No. Corrosion resistant weld overlay is considered a special process, as described in QW-381. As such, in paragraph c)of QW-381 there is no limit on maximum thickness of the weld overlay deposit used in production. Other essential variables - base metal thickness, position and diameter must be followed.

 

[GRoberts]

Since the required overlay for welder qualification is 1 1/2" wide minimum, the note is requiring that at least 3 passes be deposited even if the 1 1/2" minimum width can be achieved with less passes. This is so the welder has to demonstrate that they can adequately tie into other passes instead of depositing a 1 1/2" wide singe bead on plate.

For thickness of overlay qualified, See QW-381(c). Basically, for welder qualification, a minimum of three passes on the first layer is all that is required for unlimited thickness overlay qualification.

 

[sayee1]

As usual to the point replies by GRoberts and Metengr(a star each for yr replies). To add to what GROberts said, consider a SAW overlay using a 3.2 mm dia with a weld pass width varying from 15mm to 25mm, or a ESW(strip cladding) with a weld bead typically of widths in excess of 35mm (using a 30 * 0.5 mm strip). To satisfactorily demonstrate that the welder(s)/Welding Operator can adequately tie into other passes instead of depositing a 1 1/2" wide singe bead on plate. Note that as per QW 381(c), the essential variables listed in QW 350/QW 360 shall apply, except as pointed out by Metengr, There is no limit onthe maximum thickness of corrosion resistant overla that may be applied in production. The point is that you may have a two layer PQR/WPS with 309 type consumable for first layer and 308 type consumable for the second layer. For qualifying a welder/operator however, only one layer with 309 type consumables and with three passes and minimum width of the layer 1 1/2" should suffice (as explained by GRoberts).

Thanks and regards
Sayee Prasad R
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If it moves, train it...if it doesn't move, calibrate it...if it isn't written down, it never happened!

 

[mirhosseini]

Thanks for your good answers.
But I have a problem yet
I want write a WPS for overlay for 2 different layers,can i have a PQR with any thickness of the weld overlay deposit? there is no any limit on maximum or minimum thickness of the weld overlay deposite in my WPS?

Regards
H.Mirhosseini