BS EN ISO 3690:2001 pdf – Welding and allied processes Ð Determination of hydrogen content in ferritic steel arc weld metal.
1 Scope This International Standard specifies the sampling and analytical procedure for the determination of diffusible and residual hydrogen in ferritic weld metal arising from the welding of ferritic steel using arc welding processes with filler metal. Collection of the hydrogen over mercury is the primary method. Provided that the weld specimen size is maintained within limits dictated by the size of the test block, variations in welding parameters are permissible in order to investigate the effect of such variables on the weld hydrogen content. The techniques described in this International Standard constitute a reference method which should be used in cases of dispute. 2 Normative reference The following normative document contains provisions which, through reference in this text, constitute provisions of this International Standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent edition of the normative document indicated below. For undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards. ISO 1 41 75, Welding consumables — Shielding gases forarc welding andcutting. 3 Test procedures 3.1 Production of weld specimens 3.1.1 Principle The welding process to be tested is used to deposit a single weld bead which is rapidly quenched and subsequently stored at ? 78 °C or lower until required for preparation and analysis. 3.1.2 Welding fixture A copper welding jig for heat inputs up to 2 kJ/mm, which may be water cooled, is shown in Figure 1 . It is designed to promote the proper alignment and clamping of the test piece assembly by means of the single clamping unit which is used with a ring spanner or other suitable means. See 3.1 .4 for evidence of proper alignment and clamping.
All surfaces shall be finished at right angles to ensure good contact between adjacent pieces during the welding operation. Each test piece assembly may be finished with one operation on a surface grinder so as to ensure a uniform width, or closer dimensional control may be exercised to obtain proper clamping. See 3.1 .4 for evidence of proper clamping. Prepare three or more sets of test pieces and number them by engraving or stamping the opposite side to that to be used for welding. Number and degrease each centre test piece in each set. Determine the weight of each centre test piece (m 1 ) to the nearest 0,01 g. Degas the centre test pieces in a vacuum, or dry inert carrier gas, at 650 °C ? 1 0 °C for 1 h and cool in a vacuum or inert carrier gas prior to weighing. It is permissible to degas the steel from which the test piece assembly is made prior to machining operations, in which case it is not necessary to degas the centre piece after machining. It is also permissible to degas in air when this is followed by complete removal of surface oxide by grit blasting with a clean, dry abrasive. In case of dispute, the run-on and run-off pieces shall also be degassed. Certain welding processes, such as submerged arc, or those using high current levels, may produce weld beads incompatible with the dimensions of test piece assembly as shown aligned in Figure 1 . In this case, the test assembly shown in Figure 2 shall be used. The centre test piece is the same for both assemblies: it is rotated 90° about a vertical axis. The run-on and run-off pieces shall be compatible with the new cross-section and the length increased to accommodate the longer weld bead. Those welding processes or parameters which necessitate this alternative test piece assembly are specified in 3.2.