Section 7 Consumables for use in one-side welding with temporary backing materials

7.1.1 The requirements for approval of combinations including temporary backing material, for use in one-side welding techniques, are dependent on the technique used and which basic technique it most closely follows. The following are provided for:

1. Technique m — for manual electrode/backing combinations.

2. Technique S — for wire-gas/backing combinations used with semi-automatic multi-run technique.

3. Technique M — for wire-flux or wire-gas in combination with backing material (and maybe supplementary filler materials) used with an automatic multi-run technique.

4. Technique A — as for M but using a procedure with a high heat input rate (large bead size relative to thickness welded). This would apply to welds made by four or less runs in 20 mm thickness, or eight or less runs in 35 mm.

7.1.2 For technique m, S or M, a single butt weld is to be made in plate of 20–25 mm thickness. For technique A, two butt welds are to be made, one in plate of the maximum thickness recommended by the manufacturer, the other in plate of approximately half the thickness of the first. Usually this will involve thicknesses in the region of 35–40 mm and 20–25 mm respectively.

7.1.3 A wire and gas combination approved with an argon/carbon dioxide shielding gas where the carbon dioxide content is between 15-25 per cent is also approved for other combinations of argon/carbon dioxide, provided the carbon dioxide content is within the range 15-25 per cent. The range of approval is limited to ferritic consumables in solid wire, flux cored and coated wire forms and subject to the agreement of the consumable manufacturer and LR.

7.1.4 Any unrecognised techniques or unusual combinations will be considered for approval subject to a test programme to be agreed based on the details of the technique and combination which are to be submitted in advance.

7.1.5 Where low hydrogen approval is required either by Table 11.7.1 Minimum low hydrogen approval requirements for one-side welding with combinations including temporary backing material or by the manufacturer, it should be noted that this will generally be achieved through separate testing of:

1. the backing material, and

2. the welding electrode or combination of wire-flux or wire-gas.

7.1.6 The hydrogen potential of the backing material is to be determined using the modified Gayley-Wooding method which expresses the total hydrogen content as water by weight per cent. The qualifying levels are:

7.1.7 The sampling and approval of the combinations without the backing are to follow the general requirements of Ch 11, 3 Electrodes for manual and gravity welding, Ch 11, 4 Wire-flux combinations for submerged-arc automatic welding or Ch 11, 5 Wires and wire-gas combinations for manual, semi-automatic and automatic welding, as appropriate.

Table 11.7.1 Minimum low hydrogen approval requirements for one-side welding with combinations including temporary backing material

Approval grades		'H' grade for m and S techniques	'H' grade for M technique	'H' grade for A technique
1 (1N), 2 (2N), 3 (3N)		NR	NR	NR
1Y, 2Y, 3Y, 4Y		H15 (see Note 2)	NR	NR
2Y40 to 5Y40		H15	H15	NR
3Y47		H10	H10	H15
3Y42 to 5Y42		H10	H10	H15
3Y46 to 5Y46		H10	H10	H15
3Y50 to 5Y50		H10	H10	H10
3Y55 to 5Y55		H5	H5	H10
3Y62 to 5Y62		H5	H5	H5
3Y69 to 5Y69		H5	H5	H5
3Y89 to 4Y89		H5	H5	H5
3Y96 to 4Y96		H5	H5	H5
1 Ni		H15	H15	NR
2 Ni		H15	H15	NR
3 Ni		H15	H15	NR
5 Ni (see Note 3)		NR	NR	NR
9 Ni (see Note 3)		NR	NR	NR
Note 1. NR – Not required. Approval may be obtained when requested. Note 2. Optional in this case. If low hydrogen approval is not obtained, there is a limitation on the carbon equivalent of the steel which is permitted to be welded. Note 3. Assumes the use of an austenitic, non-transformable, filler material.

7.1.8 Combinations approved with multi-run technique (m, S and M) for normal and higher strength levels up to and including 'Y' are also considered suitable for welding steels in the three strength levels below that for which they have been approved.

7.1.9 Combinations approved with multi-run technique (m, S and M) for strength levels Y40 to Y50, but excluding Y47, are also considered suitable for welding steels in two strength levels below that for which they have been approved.

7.1.10 Combinations approved with multi-run technique (m, S and M) for strength levels Y47, Y55 and above are also considered suitable for welding steels in only one strength level below that for which they have been approved.

7.1.11 Combinations approved with multi-run technique (m, S and M) for strength level Y89 are considered suitable for welding steels in only this strength level.

7.1.12 Combinations approved with multi-run technique (m, S and M) for strength level Y96 are also considered suitable for welding steels in one strength level below that for which they have been approved.

7.1.13 Combinations approved for the 'A' multi-run technique are not considered suitable for welding steels of any other strength level with that technique.

7.2.1 For each position to be approved, one butt weld assembly is to be prepared using plates of 20 — 25 mm thickness as shown in Figure 11.7.1 Butt weld test assembly and specimens for all techniques. The grade of plate used is to be no higher in toughness than that for which approval is required. The strength is to be appropriate to the grade for which welding approval is requested.

7.2.2 The thickness of test assembly may be taken as 50 mm for Y47 base material.

Figure 11.7.1 Butt weld test assembly and specimens for all techniques

7.2.3 The edge preparation and welding conditions are to be in accordance with the recommendations of the manufacturers. For the m and S techniques, the assembly is to be welded using, for the first run wire of the smallest diameter recommended by the manufacturer and, for the remaining runs, wire of the largest diameter to be approved. For the M technique any size wire as recommended by the manufacturer can be used.

7.2.4 Test specimens are to be prepared as shown in Figure 11.7.1 Butt weld test assembly and specimens for all techniques and Figure 11.7.2 Position of Charpy V-notch impact tests for one-side automatic welding:

1. One longitudinal tensile test specimen (from the centre of the weld).

2. Two transverse tensile specimens.

3. Two bend test specimens, one with the face in tension, the other with the root in tension.

4. One macrosection.

5. Two sets of three Charpy impact test specimens positioned and notched in accordance with Figure 11.7.2 Position of Charpy V-notch impact tests for one-side automatic welding.

Figure 11.7.2 Position of Charpy V-notch impact tests for one-side automatic welding

7.2.5 The results of all transverse tensile, bend and impact tests are to comply with the requirements in Table 11.3.3 Requirements for butt weld tests (covered electrodes) for m and S technique, and Table 11.4.3 Requirements for butt weld tests (wire-flux combinations) for M technique. The position of fracture of the transverse tensile test is to be reported. The appearance of the bend test specimens is to be in accordance with Ch 11, 3.3 Butt weld test assemblies 3.3.13.

7.2.6 The results of all longitudinal tensile tests are to comply with the requirements in Table 11.3.2 Requirements for deposited metal tests (covered electrodes).

7.2.7 Low hydrogen approval is required in accordance with Table 11.7.1 Minimum low hydrogen approval requirements for one-side welding with combinations including temporary backing material.

7.2.8 Chemical analyses are to be made and reported from positions corresponding to the weld metal in the upper and lower Charpy specimens of the downhand butt weld. These are to be supplied by the manufacturer and are to include the content of all significant elements. The results of the analysis are not to exceed the limit values specified in the standards or by the manufacturer, the narrower tolerances being applicable in each case.

7.3.1 Two butt weld assemblies are to be prepared, usually one of 35–40 mm thickness, the other 20–25 mm, as shown in Figure 11.7.1 Butt weld test assembly and specimens for all techniques, noting that in the thinner assembly only two sets of Charpy specimens are required. The grade of plates used is to be no higher in toughness than that for which approval is required. The strength is to be appropriate to the grade for which welding approval is requested.

7.3.2 For Y47 grade, the thicker assembly is to be prepared from the maximum thickness for which approval is required, and the thinner assembly is to be prepared from 50 mm thickness. Where approval is required for 50 mm thickness, only one assembly from that thickness is required.

7.3.3 The edge preparation and welding conditions are to be in accordance with the manufacturer's recommendations, and are to be reported to LR. The diameters of wires are to be in accordance with the recommendations of the manufacturer and are to be reported.

7.3.4 Test specimens as follows are to be prepared as shown in Figure 11.7.1 Butt weld test assembly and specimens for all techniques and Figure 11.7.2 Position of Charpy V-notch impact tests for one-side automatic welding:

1. One longitudinal tensile test specimen (from centre of weld).

2. Two transverse tensile test specimens.

3. Two bend test specimens.

4. One macro-section.

5. From assembly 20 to 25 mm thick, two sets of three impact test specimens positioned and notched in accordance with Figure 11.7.2 Position of Charpy V-notch impact tests for one-side automatic welding.

6. From assembly 35 to 40 mm thick, three sets of three impact test specimens positioned and notched in accordance with Figure 11.7.2 Position of Charpy V-notch impact tests for one-side automatic welding.

7. From assembly of thickness 50 mm or more, three sets of three impact test specimens positioned and notched in accordance with Figure 11.7.2 Position of Charpy V-notch impact tests for one-side automatic welding. The second set positioned in the mid-thickness of test assembly.

The bend specimens are to be tested, one with the face in tension, the other with the root in tension.

7.3.5 The results of all transverse tensile, bend and impact tests are to comply with the requirements of Table 11.4.3 Requirements for butt weld tests (wire-flux combinations). The appearance of the bend test specimens is to be in accordance with Ch 11, 3.3 Butt weld test assemblies 3.3.13. The Charpy V-notch impact test requirements are as for the two-run technique in Table 11.4.3 Requirements for butt weld tests (wire-flux combinations).

7.3.6 The results of all longitudinal tensile tests are to comply with the requirements in Table 11.3.2 Requirements for deposited metal tests (covered electrodes), except that for Grades 1Y, 2Y and 3Y the tensile strength is to be not less than 490 N/mm².

7.3.7 Low hydrogen approval is required in accordance with Table 11.7.1 Minimum low hydrogen approval requirements for one-side welding with combinations including temporary backing material.

7.3.8 Chemical analyses are to be made and reported from positions corresponding to the weld metal in the uppermost and lowest Charpy specimens in the thicker plate weld. This is to be supplied by the manufacturer and is to include the content of all significant elements. The results of the analysis are not to exceed the limit values specified in the standards or by the manufacturer, the narrower tolerances being applicable in each case.

7.4.1 Annual tests are to consist of, at least, one butt weld test assembly, for each technique approved, using plates of 20 to 25 mm thickness. For the Y47 grade the thickness of plates may be taken as 50mm.

7.4.2 The assembly is to be prepared and tested in accordance with Ch 11, 7.2 Approval tests for manual (m), semi-automatic (S) and automatic multi-run (M) techniques or Ch 11, 7.3 Approval tests for high heat input automatic (A) techniques , as appropriate, except that only the following tests are required:

1. One longitudinal tensile test (from centre of weld).

2. One transverse tensile test.

3. Two bend tests.

4. One set of three impact tests taken from the root of the weld and the specimens notched in accordance with Figure 11.7.2 Position of Charpy V-notch impact tests for one-side automatic welding.

5. Chemical analysis (one only).

7.4.3 A hydrogen test is required for Y89 and Y96 grades.