12-28-2015 Council Packet - Laserfiche WebLink

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SP0178-2007 Section 4: Fabrication Practices 4.1 All design practices in Section 3 shall apply to all fabrication. 4.2 All welding shall be continuous. Intermittent or spot welding shall not be allowed. 4.3 Fillets and corners must be accessible for grinding. 4.4 Field tanks fabricated for use with high -heat -cured linings (e.g., unmodified phenol formaldehyde thermosetting linings) should have bottoms suitably insulated and installed on properly drained foundations to facilitate proper cure of the lining on the floor of the tank. Because the sand -filled earthen foundation, concrete pad, or other similar foundation is a poor insulator, some means must be considered prior to the application of the lining either to override the heat sink or to distribute the heat uniformly. This may be accomplished in several ways: (a) with the use of properly sized heaters; (b) by placing the tank on a concrete pad topped with a 100 -mm (4 -in.) layer of vermiculite concrete; (c) by insulating with a high -compressive -strength structural grade insulation between the tank bottom and foundation; (d) by installing an internal temporary false bottom approximately 1.5 m (5.0 ft) above the floor of the tank prior to the final high-temperature bake; or (e) by other suitable means that practically and effectively ensure a properly cured lining on the tank floor. Section 5: Surface Finish Practices 5.1 Sharp edges shall be ground to a smooth radius of at least 3.2 mm (0.13 in.) or as agreed between the tank or vessel fabricator, tank or vessel owner, and lining applicator. 5.2 Tank and vessel internal surfaces to be lined shall not be marred by gouges, handling marks, deep scratches, metal stamp marks, slivered steel, or other surface flaws. Flaws shall be repaired by welding or grinding, as appropriate. 5.2.1 Limits on surface flaw depth and geometry shall be set by agreement between the tank or vessel fabricator, tank or vessel owner, and lining applicator. 5.2.2 All restorative welding shall be performed according to applicable tank or vessel design codes, approved job -specific procedures, or both. 5.3 All rough welds shall be ground to remove sharp edges and other such irregularities (see Figure A2, Appendix A). Chipping may be used to remove sharp edges if followed by grinding. See Appendix C for written and graphic descriptions of five degrees of surface finishing of welds that may be specified preparatory to the lining of tanks and vessels. 5.3.1 The amount of grinding performed shall be judicious and performed only to the extent necessary to prepare the weld surface and surrounding metal surfaces in accordance with the specification. Over - grinding, which would result in decreasing the wall thickness or the integrity of the weld beyond the limitations imposed by good welding practices, applicable welding codes, or tank or vessel ratings, shall be avoided. 5.4 Automatic machine welds may be acceptable as dictated by the specifications for film continuity. 5.5 All weld spatter and arc strikes must be removed. Chipping may be used if followed by grinding or the use of an abrasive disc. 5.6 If an anti -spatter material is applied adjacent to the weld area prior to welding, the anti -spatter material shall be one that is readily removable. Anti -spatter materials shall be removed prior to abrasive blasting. 5.7 When checking weld continuity, the tank or vessel fabricator shall avoid the use of oils, lubricants, or other foreign materials that would leave a contaminating residue not easily removed by abrasive blasting. 5.8 Surfaces shall be cleaned and decontaminated as required by the governing lining application specification(s). NACE International 3