SECTION 5 QUALIFICATION OF A WELDING PROCEDURE
5.12 IDENTIFICATION OF THE TEST WELD
Each qualified welding procedure and each welder or operator shall be uniquely identified.
This identification shall be clearly marked on the test piece adjacent to the weld.
TABLE 5.4.2(A)
ITEMS FOR QUALIFIED PROCEDURES
Item (see Note 1) Remarks
PIPE
1 (a) Material specification Pipe and components complying with the AS 2885 set of Standards, another relevant Australian Standard, or another Approved Standard
(b) Material manufacturer Where material grade ≥X70 (c) Material carbon equivalent (CE)
15
2 Wall thickness Nominal wall thickness of each component of the joint 3 Diameter group Applicable to the diameter of each pipe, branch pipe or
component
PROCESS
4 Welding process The arc welding process (e.g., MMAW, automatic GMAW, GTAW, or a nominated combination)
DESIGN
5 Preparation Joint preparation e.g., type and details of bevel, root face, and gap, and the dimensional tolerances upon the preparation. For high-low limits refer to Clause 15.4.3 6 Weld shape and size Shape and size of welds
7 Backing Type of backing or consumable insert (if used)
8 Passes Number and sequence of passes (including stripper passes) 9 Position Positions shown in Table 4.2(A)
10 Direction of welding Vertical up or vertical down
FILLER
11 Filler metal Size and classification of electrode or welding wire for each pass
SHIELDING
12 Shielding gas (a) Type and composition of gas or gas mixture used for shielding or backing
(b) Nozzle or cup size
(c) Type and flow rate for shielding or backing gases 13 Shielding flux Type, size, classification, make, and brand of flux ELECTRICAL
14 Electrical characteristics Arc type, current, polarity and voltage for each size of electrode.
PROCEDURE
15 Number of welders Minimum number of root and hot pass welders 16 Removal of line-up clamp, and/or type
of lift (see Note 4)
Minimum percentage of root pass completed before release of clamp. Where less than 100% the location of the
completed proportion shall be specified (see Notes 5 and 6).
The type of lift shall also be specified 17 Tack welding (if used) Number and size of tacks employed
(continued)
Accessed by GHD PTY LTD on 05 Aug 2009
Item (see Note 1) Remarks
18 Maximum Time lapse between individual time lapse—
passes (see Note 2)
(a) between the start of the root pass and the start of the hot pass; and
(b) between subsequent passes 19 Preheat temperature and interpass
temperature
Heating method, width heated, preheat temperature and interpass temperature
(a) For post-weld heat treatment, the heating method, width heated, minimum and maximum temperature, time at temperature, method of temperature
measurement, and control of maximum and minimum cooling rates
20 Post-weld heat treatment and post-weld cooling
(b) For deliberate accelerated post weld cooling above 100°C, the method and intensity or rate of cooling 21 Heat input or burn-off rate
(see Note 3)
Heat input or burn-off rate for each pass
CLEANING
22 Cleaning Equipment and method used
DEFECT ACCEPTANCE CRITERIA 23 Visual inspection and NDE acceptance
criteria
The tier of acceptance criteria for girth weld discontinuity
NOTE: Item indicates the specification topic.
TABLE 5.4.2(A) (continued)
TABLE 5.4.2(B)
ESSENTIAL VARIABLES FOR QUALIFIED WELDING PROCEDURES
Item (see Note 1) Essential variable
PIPE
1 Material (a) Change of material grade between <X70 and ≥X70 or from X70 to a higher grade
(b) Where material grade ≥X70—Material manufacturer (combinations between different material manufacturers do not require separate qualification, see Clause 5.8(b)) (c) For actual CE values of < 0.35, an increase of carbon
equivalent of > 0.05 above that used for the procedure test weld
(d) For actual CE values of ≥ 0.35, an increase of carbon equivalent of > 0.03 above that used for the procedure test weld (see Clause 5.6.1(b))
2 Wall thickness (see Note 5) Tier 1: Change of material thickness in a component of a joint between <0.5 nominal thickness and >1.2 nominal thickness
Tier 2 and Tier 3: Change of material thickness in joints with the same nominal thickness between <1 nominal thickness and >1.2 nominal thickness
In tapered joints or branch welds the thickness to be
considered shall be the effective thickness on the thicker side of the joint. The effective thickness shall be as defined in WTIA Technical Note 1
3 Diameter group (see Note 4)
Change in nominal outside diameter outside the diameter groups qualified as follows:
(a) D ≤60.3 mm
(b) 60.3 mm < D ≤508 mm
(c) D >508 mm where D is the nominal diameter of the test weld
Or, as an alternative to the diameter groups given above, where there is a change in diameter from a qualified
procedure of more than 50% of the nominal outside diameter PROCESS
4 Welding process (a) A change from one welding process or combination to another
(b) Change from a manual operation to semi-automatic or automatic operation, or vice versa
(c) Change of automatic welding system used DESIGN
5 Preparation (a) Any change to the nominal dimensions of the weld preparation and their tolerances
(b) An increase in the permitted level of high-low beyond the limits of Clause 15.4.3
6 Weld shape and size Change beyond that permitted by joint design (see Clause 10) 7 Backing Deletion or addition or change of a backing material or
consumable insert
(continued)
Accessed by GHD PTY LTD on 05 Aug 2009
TABLE 5.4.2(B) (continued)
Item (see Note 1) Essential variable
8 Passes Not limited unless it is a reduction to less than 4 passes 9 Position Change in position other than as permitted by Table 4.2(A) 10 Direction of welding Change between vertical up and vertical down
FILLER 11 Filler metal (electrodes,
filler wire)
(a) Any change in classification of welding consumables as specified by Table 2.2.1
(b) Change in diameter of electrode, filler wire or rod for the root pass
(c) For single-sided butt welds and fillet welds, any change of root pass electrode brand name
(d) For electrodes of higher strength than E4110, a change in any of the following:
(i) The type or nominal level of alloying elements used in the weld metal
(ii) Manufacturer and factory of origin
(iii) A significant change in the proportion of the thickness welded with different electrode classifications
(e) For GMAW or FCAW electrodes, a change in brand designation, factory of origin or electrode diameter SHIELDING
12 Shielding gas (a) Change between one gas or mixture and another gas or mixture
(b) Decrease in shielding gas flow rate by more than 10% or decrease in the nozzle or cup size
(c) Change of gas backing parameters 13 Shielding flux (a) Change in flux type, size, classification
(b) Change in combination of flux and electrode, which results in a different classification number
ELECTRICAL
14 Electrical characteristics (a) Change of polarity of the electrode
(b) Change of electrical current between a.c. and d.c.
(c) Change of arc type between spray arc, globular arc, pulsed arc, and short-circuiting (dip transfer) arc or between the use of a conventional power source and a controlled waveform power source.
(d) Change of more than 10% in contact tube-to-work distance
(e) Change of current and/or voltage to a value outside the manufacturer’s published recommended range or, when working outside the manufacturer’s recommended range, the qualified range of values of current and/or voltage PROCEDURE
15 Number of welders Decrease in number of welders used on any root pass, or hot pass, in the procedure test weld
(continued)
16 Removal of line-up clamp
(if used) and/or a change in the type of lift
(a) A reduction in the proportion of root pass welded before the line-up clamp is released
(b) A change from normal to extreme lift (see Appendix E)
17 Tack welding (if used) A reduction in the number or size of tack welds or both 18 Time lapse between individual passes
(see Note 2 and Clause 5.10)
Increase in time lapse beyond the qualified range
19 Preheat temperature and interpass temperature
(a) For material grades of less than X70 a decrease in material temperature of more than 25°C below or an increase of more than 75°C above that used in the procedure test weld
(b) For material grades of X70 or higher a decrease in material temperature of more than 10°C below or an increase of more than 75°C above that used in the procedure test weld
Note: Refer to Clause 5.9 which requires the test weld to be made under conditions that simulate the worst case to be encountered in production.
20 Post-weld heat treatment and post- (a) Change in post-weld heat treatment weld cooling
(b) Change in post-weld cooling method and intensity, or rate of cooling (see Clause 3.2)
21 Heat input or burn-off rate (see Note 3)
(a) For mechanized or automatic welding, a change of heat input of more than 15% of the nominated average used in the procedure test weld
(b) For manual metal-arc welding a reduction of heat input or burn-off rate on the root pass of more than 10%, or on the other passes a change of more than 20%
22 Cleaning Equipment and method used
DEFECT ACCEPTANCE CRITERIA 23 Visual examination and NDE
acceptance criteria
An increase in the Tier number
TABLE 5.4.2(B) (continued) TABLE 5.4.2(B) (continued) TABLE 5.4.2(B) (continued)
Accessed by GHD PTY LTD on 05 Aug 2009
NOTES TO TABLE 5.4.2(B)
1 The essential variable specifies the limits outside which re-qualification is required. Changes in non-essential variables require documentation but do not require re-qualification. Non-non-essential variables are those Items in Table 5.4.2(A) which are not listed as essential variables in Table 5.4.2(B).
2 The method of defining time lapse shall be the same for production welds as is used for procedure qualification welds. It is recommended that the time lapse from start of root pass to start of hot pass be the defined method to avoid uncertainties associated with root repairs.
3 Burn-off rate is defined as the ratio of length of electrode consumed to the length of weld pass deposited. WTIA Technical Note 1 provides information relating burn-off rate to heat input.
4 The essential variables in Table 5.4.2(B) primarily address the risk of HACC. This is clearly evident by the latitude extended to the range of thickness (Item 2). Tier 2, however, permits increased defect limits based on demonstrated mechanical properties, i.e., weld metal strength matching and fracture toughness. Although Tier 2 defect limits are proportional to wall thickness, variations in wall thickness can strongly influence defect tolerance. This is principally a consequence of the fact that planar defects are assumed to be one weld pass deep (i.e., 3 mm). Such an assumed defect depth in thin-walled pipe can significantly change the requirement of weld strength matching (despite the proportional decrease in defect limit). For this reason the Tier 2 and Tier 3 lower limit multiplier for thickness range is more restrictive than that for Tier 1.
5 Research work carried out by the CRC for welded structures (CRC-WS) has shown that for normal lifts (see Appendix F) the additional strains, over and above the weld contraction strains, caused by lifting and lowering are small for pipe diameters less than DN 500 It has also shown that providing due attention is paid to the other factors governing the risk of HACC, the removal of the line-up clamp after at least 50% of the root pass is completed, does not by itself cause cracking.
6 The proportion of the root pass that is completed before clamp release shall be ≥50%.
7 Where the proportion of the root pass that is completed before the line-up clamp is released is <100%, then at least 80% of both the top and bottom quadrants shall be completed before clamp release.