AWS D10.12M – D10.12 pdf free download
AWS D10.12M – D10.12 pdf free download.Guide for Welding Mild Steel Pipe.
3. General
With different welding processes, certain terminology, specifications, preparations, and practices apply. This includes the types of steel, joint preparation, joint alignment, tack welding, and welding positions used.
3.1 Pipe Steels. These procedures are intended to he used for welding piping systems composed of such carbon steels as ASTM A 53, A 106, A 135, A 179, A 524, A 587, and API-5L, Grades A25, A and B. and X42. Pipe sizes to be welded with these procedures are not greater than DN 200 (NPS 8) maximum, with wall thicknesses up to 13 mm (0.5 in.) maximum. If this information is applied to larger diameters, or greater wall thicknesses, consideration should be given to service conditions which may go beyond the scope of this document.
3.2 Cleanliness. Cleanliness is important in all welding. Care should be taken to ensure that both members of the joint are properly cleaned. Each side of a weld joint should be mechanically cleaned of all paint, scale, rust or other hydrocarbon containing materials (i.e., oils) for a distance of approximately 25 mm (1 in.) from the end of the expected toe of the weld. Pipe joints should be cleaned on both the inside and outside surfaces. Grinding and cleaning should be done just prior to joint alignment. Improper or insufficient cleaning can result in discontinuities such as porosity, undercut, incomplete fusion, and cracks.
3.3 Preheating. Preheating is not normally required when welding the pipe, fittings and other components of similar nominal composition to those listed in paragraph 3.1 except when the ambient temperature is below 0°C (32°F) or there is visible moisture on the pipe. In these cases, the pipe should be heated using a fuel gas torch or by other suitable methods to 38°C (100°F) minimum.
Preheating to 107°C (225°F) is recommended. In addition, use of a low-hydrogen welding process or, when E6010 or E601 I is used for root pass welding, use of a low-hydrogen process or electrodes for fill passes is recommended for metals meeting the above conditions.
3.4 Joint Preparation. The joint preparation details and dimensions given in the following procedures are necessary to attain the required quality. Figure 1 shows the proper terminology for describing joint preparation.
3.5 Alignment and Tack Welding. The use of clamps to secure proper alignment is highly recommended. For pipe diameters covered in this document, external lineup clamps are usually employed. A few representative designs have been illustrated in Figure 2.
External clamps with typical cross bars will not allow access for welding around the full circumference of the pipe. For this reason, tack welds should be made in three or four locations between the cross-bars. Tack welds should be of sufficient size to hold the pipe together after the clamp is released and before the root pass is completed. If the shape and size of tack welds arc not conducive to their subsequent inclusion in the root pass without risking areas of incomplete fusion or incomplete joint penetration, they should be ground to a contour that will permit complete fusion and penetration.
3.6 Welding Positions. Pipe can he welded in all positions. Welders may be qualified in one or more of the positions shown in Figure 3. Each position is identified by a “G” number in Figure 3 where “G” stands for groove.
AWS D10.12M – D10.12 pdf download.
