As per ASME Sec-IX, QW-253 & QW405.3 (i.e welding progression is a 'Non essential Variable (NEV)') since uphill/down hill progression is NEV, a PQR with uphill can be used for both uphill & downhill and vice versa. But it is a EV (essential variable) for Welder qualification as per QW-353.
E7018 is not suitable for vertical down welding, the contractor can revise the WPS with suitable electrode (E7048) (refer SFA 5.1 table-1), with the same PQR qualified with E7018.
As per code it is legal to weld 'up to down' and vice versa, but quality point of view, I feel vertical down welding will have some quality issues for tank welding (may be practical problems). But we cannot argue since code permits this!
Please check your client spec, permits this deviation (vertical down welding) in tank welding?
But in WQT be strict, the welders shall qualify in vertical down welding only.
I was read API 650 also, I couldn't able to find any clause to object 'V down' welding?
Hope this clarifies,
cheers,
Raj
Dear Gents,--
The objective of writing this post is seeking your precious help in solving a problem regarding Welding Procedure Qualification
It is required to qualify a Welding Procedure specification for welding the bottom shell plates of an Oil storage tank.
Is it possible to use ESAB ATOM ARC 7018 electrode for Vertical down welding of the shell plates?
As per the AWS 5.1 -2004 Table-1 Electrode Classification, this electrode cannot be used for Vertical down welding and only E7048 can be used for vertical down welding.
According to ASME SEC IX, ( WELDING VARIABLES PROCEDURE SPECIFICATIONS (WPS) Shielded Metal-Arc Welding (SMAW) ) QW-253 the Position QW- 405 is a supplementary essential variable only.
Now the contractor has successfully completed the Welding Procedure Qualification Test using ESAB ATOM ARC 7018 in the vertical down position and submitted for approval.
Kindly advise, is it fair to accept it? Will there be any quality related problems in using this WPS and the ESAB ATOM ARC 7018 for welding Oil storage tanks as per API 650 standards?
The relevant portion of the ASME SEC IX extract, the brochure of ESAB ATOM ARC 7018 and the AWS 5.1-2004 are attached along with this.
Thanking You
Regards
Best Regards,Suresh.
QW-253WELDING VARIABLES PROCEDURE SPECIFICATIONS (WPS) Shielded Metal-Arc Weldi
QW-410
Technique
Paragraph
Brief of Variables
Essential
Supplementary
Essential
Nonessential
QW-402
Joints
.1
Groove design
X
.4
− Backing
X
.10
Root spacing
X
.11
± Retainers
X
QW-403
Base
Metals
.5
Group Number
X
.6
T Limits impact
X
.8
T Qualified
X
.9
t Pass > 1⁄2 in. (13 mm)
X
.11
P-No. qualified
X
QW-404
Filler
Metals
.4
F-Number
X
.5
A-Number
X
.6
Diameter
X
.7
Diameter > 1⁄4 in. (6 mm)
X
.12
Classification
X
.30
t
X
.33
Classification
X
QW-405
Positions
.1
+ Position
X
.2
Position
X
.3
¯ Vertical welding
X
QW-406
Preheat
.1
Decrease > 100°F (55°C)
X
.2
Preheat maint.
X
.3
Increase > 100°F (55°C) (IP)
X
QW-407
PWHT
.1
PWHT
X
.2
PWHT (T & T range)
X
.4
T Limits
X
QW-409
Electrical
Characteristics
.1
> Heat input
X
.4
Current or polarity
X
X
.8
I & E range
X
.1
String/weave
X
.5
Method cleaning
X
.6
Method back gouge
X
.9
Multiple to single pass/side
X
X
.25
Manual or automatic
X
.26
± Peening
X
.64
Use of thermal processes
X
Legend:
+ Addition
> Increase/greater than
Uphill
¬ Forehand
Change
− Deletion
< Decrease/less than
¯ Downhill
® Backhand
22
QW-253.1
WELDING VARIABLES PROCEDURE SPECIFICATIONS (WPS) Shielded Metal-Arc Welding (SMAW)
Special Process Variables
QW-403
Paragraph
Essential Variables
Nonessential
Variables for HFO
and CRO
Hard-Facing
Overlay (HFO)
(QW-216)
Corrosion-Resistant
Overlay (CRO)
(QW-214)
QW-402
Joints
.16
< Finished t
< Finished t
.20
P-Number
P-Number
.23
T Qualified
T Qualified
Base
Metals
QW-404
Filler
Metals
.12
Classification
.37
A-Number
.38
Diameter (1st layer)
QW-405 .4 + Position + Position
Positions
QW-406 .4
Dec. > 100°F (55°C) preheat Dec. > 100°F (55°C) preheat
Preheat > Interpass > Interpass
QW-407
PWHT
.6
PWHT
.9
PWHT
QW-409
Electrical
Characteristics
.4
Current or polarity
Current or polarity
.22
Inc. > 10% 1st layer
Inc. > 10% 1st layer
QW-410
Technique
.1
String/weave
.5
Method of cleaning
.26
± Peening
.38
Multiple to single layer
Multiple to single layer
Legend:
+ Addition
> Increase/greater than
Uphill
¬ Forehand
Change
− Deletion
< Decrease/less than
¯ Downhill
® Backhand
To post to this group, send email to materials-welding@googlegroups.com
To unsubscribe from this group, send email to materials-welding+unsubscribe@googlegroups.com
For more options, visit this group's bolg at http://materials-welding.blogspot.com/
The views expressed/exchnaged in this group are members personel views and meant for educational purposes only, Users must take their own decisions w.r.t. applicable code/standard/contract documents.
To post to this group, send email to materials-welding@googlegroups.com
To unsubscribe from this group, send email to materials-welding+unsubscribe@googlegroups.com
For more options, visit this group's bolg at http://materials-welding.blogspot.com/
The views expressed/exchnaged in this group are members personel views and meant for educational purposes only, Users must take their own decisions w.r.t. applicable code/standard/contract documents.
No comments:
Post a Comment