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SP0178-2007 Section 1: General 1.1 This standard presents standard practices for the design, fabrication, and surface finish of tanks and vessels to be lined for immersion service. Tanks and vessels may be lined for corrosion control or to prevent product contamination. 1.1.1 Appendix A (mandatory) contains illustrations depicting both good and bad practices for tanks and vessels to be lined for immersion service. 1.1.2 Appendix B (nonmandatory) contains a list of recommended responsibilities of the purchaser (user), designer, fabricator, lining applicator, and inspector to ensure that an acceptable lining application is achieved. 1.1.3 Appendix C (nonmandatory) contains written and graphic descriptions of five degrees of surface preparation of welds in tanks and vessels that may be specified prior to lining. The written descriptions of the five degrees of surface preparation of welds in Appendix C take precedence over the graphics and the companion visual comparator. The graphics are only pictorial representations of welds and grinding finishes and are not intended to be representative of the integrity of the welds. The "weld condition prior to finishing" is not a typical weld; it is only intended to illustrate defects in welds that must be corrected prior to lining. 1.2 Good welding practices and welding codes govern the integrity of the tank and vessel welds; this standard only addresses surface preparation of the welds for the purpose of lining the tank or vessel for immersion service. 1.3 Other design and construction codes or standards may be used to complement the details given here. When applicable, the requirements of such other codes or standards shall be considered. A partial list of such codes and standards can be found in the Bibliography. 1.4 These standard practices may be used in the design, fabrication, and surface finish of tanks and vessels for services other than immersion, such as dry bulk storage of solid materials. Section 2: Definitions Lining: A coating or layer of sheet material adhered to or in intimate contact with the interior surface of a container used to protect the container against corrosion by its contents and/or to protect the contents of the container from contamination by the container material. For the purposes of this standard, lining refers to a surface barrier, usually a thin film less than 500 pm (20 mil) thick applied as either a lining or a coating. In common usage, the terms coating and lining are interchangeable, but in this standard, only the term lining is used. The requirements contained herein may or may not apply to heavier, thick -film linings, sheet linings, trowel -applied and pumped -into -place finishes, plasma, 3.1 Accessibility flame -sprayed linings, fiber -reinforced plastic linings, or similar lining materials. Surface Finish: The degree of smoothness of a surface produced by the removal of sharp edges and the appropriate surface preparation of welds and other rough areas. The term surface finish is also used to characterize the degree of smoothness that is necessary to attain a surface to which the lining can be applied satisfactorily in accordance with the lining specification. Section 3: Design Practices 3.1.1 All surfaces of the tank or vessel interior shall be readily accessible for surface preparation and lining application (see Figures Al through Al 0, Appendix A). 3.1.2 The manway diameter for working entrance and safety reasons during the lining application shall be as large as practical for the tank or vessel being lined. 3.1.2.1 If possible, at least one manway shall be located near ground (working) level, except in tanks or vessels designed to be buried below grade. 3.1.3 Additional manways and openings should be provided as needed to facilitate ventilation. These must meet safety requirements. 3.2 Joints 3.2.1 Continuous butt -welded joints shall be used whenever possible (see Figure A5, Appendix A). NACE International 1