AWS D3.9/D3.9M:2019 pdf free download

AWS D3.9/D3.9M:2019 pdf free download.Specification for the Classification of Weld-Through Paint Primers.
4. Test Assembly Preparation
4.1 Base Material. The base material shall be ASTM A36/A36M, ASTM Al 31/Al 31 M or other steel with a minimum specified yield strength that does not exceed 50 ksi [350 MPaJ.
4.2 Surfaces. All surfaces shall be blast cleaned in accordance with SSPC-SP 1 0/NACE No. 2, Near-White Blast Cleaning with a surface profile of 1.5 to 2.5 mi Is [38 to 64 microns]. The surface profile shall be measured using a profile comparator (ASTM D441 7, Method A), a profile depth gage (ASTM D441 7, Method B) or replica tape (ASTM D441 7, Method C).
4.3 Spray Paint. Following preparation, and attachment of shims (see 4.5), all surfaces shall be spray painted as uniformly as possible with the primer to obtain the required dry film thickness. In order to simulate welding of sections which have the bottom edge of the vertical piece primed, some tests may be carried out with the primer applied at double the required dry film thickness on side C, as shown in Figure 1. Where all tests qualifying a particular primer were performed on assemblies with double the required film thickness on side C, the suffix “—2T’ may be added to the classifications listed in section 62.
4.4 Curing Primer Coated Plates. Prior to weld testing, the primer coated plates shall be allowed to cure in accordance with the manufacturer’s recommendations.
4.5 Steel Shims. Prior to spraying the shop primer, four steel shims shall be attached to each surface, sides A, B and C in Figure 1, in areas which will not interfere with the welding test. The locations shall be equally spaced along the length of each of the three surfaces. Bare substrate readings of the steel shims shall be taken prior to spraying, using a Type 2 electromagnetic induction dry film gage in accordance with SSPC PA 2. The dry film thickness of the paint shall be measured and the difference in the two readings recorded. The coating thickness measurement of each shim shall consist of the average of three individual gage readings within 1 in [25 mm] of each other. A total of 12 measurements per assembly shall be made.
The 12 values shall be recorded on the test report data sheet.
If the dry film thickness of side C has not been doubled as permitted in 4, the average of these twelve readings shall be considered the primer thickness for purposes of qualification, If the dry film thickness of side C has been doubled as permitted in 4, the primer thickness for purposes of qualification shall be calculated as follows:AWS D3.9/D3.9M:2019 pdf free download.