1、 NACE International i Standard Practice Design, Fabrication, and Surface Finish Practices for Tanks and Vessels to Be Lined for Immersion Service This NACE International standard represents a consensus of those individual members who have reviewed this document, its scope, and provisions. Its accept
2、ance does not in any respect preclude anyone, whether he or she has adopted the standard or not, from manufacturing, marketing, purchasing, or using products, processes, or procedures not in conformance with this standard. Nothing contained in this NACE International standard is to be construed as g
3、ranting any right, by implication or otherwise, to manufacture, sell, or use in connection with any method, apparatus, or product covered by Letters Patent, or as indemnifying or protecting anyone against liability for infringement of Letters Patent. This standard represents minimum requirements and
4、 should in no way be interpreted as a restriction on the use of better procedures or materials. Neither is this standard intended to apply in all cases relating to the subject. Unpredictable circumstances may negate the usefulness of this standard in specific instances. NACE International assumes no
5、 responsibility for the interpretation or use of this standard by other parties and accepts responsibility for only those official NACE International interpretations issued by NACE International in accordance with its governing procedures and policies which preclude the issuance of interpretations b
6、y individual volunteers. Users of this NACE International standard are responsible for reviewing appropriate health, safety, environmental, and regulatory documents and for determining their applicability in relation to this standard prior to its use. This NACE International standard may not necessa
7、rily address all potential health and safety problems or environmental hazards associated with the use of materials, equipment, and/or operations detailed or referred to within this standard. Users of this NACE International standard are also responsible for establishing appropriate health, safety,
8、and environmental protection practices, in consultation with appropriate regulatory authorities if necessary, to achieve compliance with any existing applicable regulatory requirements prior to the use of this standard. CAUTIONARY NOTICE: NACE International standards are subject to periodic review,
9、and may be revised or withdrawn at any time in accordance with NACE technical committee procedures. NACE International requires that action be taken to reaffirm, revise, or withdraw this standard no later than five years from the date of initial publication and subsequently from the date of each rea
10、ffirmation or revision. The user is cautioned to obtain the latest edition. Purchasers of NACE International standards may receive current information on all standards and other NACE International publications by contacting the NACE International FirstService Department, 1440 South Creek Dr., Housto
11、n, Texas 77084-4906 (telephone +1 281/228-6200). Revised 2007-03-10 Reaffirmed 2003-03-17 Reaffirmed September 1995 Reaffirmed March 1991 Revised 1989 Approved 1978 NACE International 1440 South Creek Drive Houston, Texas 77084-4906 +1 281/228-6200 ISBN 1-57590-167-6 2007, NACE International NACE SP
12、0178-2007 (formerly RP0178-2003) Item No. 21022 SP0178-2007 NACE International i _ Foreword When specifying tanks and vessels that are to be internally lined to control corrosion and prevent product contamination, special design, fabrication, and surface finishing practices must be considered to obt
13、ain the desired performance of these linings for immersion service. As the corrosiveness of the product increases, the design and fabrication of the tank or vessel becomes more critical relative to the performance of the lining. This standard presents standard practices for the design, fabrication,
14、and surface finish of metal tanks and vessels that are to be lined for corrosion resistance and to prevent product contamination. The standard explains how the standard practices govern the quality of lining applications. Appendix A contains illustrations depicting both good and bad practices for ta
15、nks and vessels to be lined, and Appendix B contains a list of recommended responsibilities to ensure that an acceptable lining application is achieved. Appendix C contains written and graphic descriptions of five degrees of surface preparation of welds in tanks and vessels that may be specified pri
16、or to lining.(1)This standard is intended for use or reference by end users, lining specifiers, lining applicators, lining manufacturers, and contracting authorities involved in the surface preparation or lining installation in tanks and vessels intended for chemical immersion service. This standard
17、 practice was originally prepared in 1978 by NACE International Task Group (TG) T-6A-29, a component of Unit Committee T-6A on Coating and Lining Materials for Immersion Service, in collaboration with Unit Committee T-6H on Application and Use of Coatings for Atmospheric Service. The standard was re
18、vised in 1989 by TG T-6G-27, a component of Unit Committee T-6G on Surface Preparation for Protective Coatings, and was reaffirmed in 1991 and 1995. It was reaffirmed in 2003 by Specific Technology Group (STG) 04 on Coatings and Linings, Protective: Surface Preparation. The standard was revised in 2
19、007 by TG 295 on Lining, Tanks and Vessels for Immersion Service: Fabrication Details, Surface Finish Requirements, and Proper Design ConsiderationsReview of NACE Standard RP0178-2003. This TG is administered by STG 04. It is also sponsored by STG 02 on Coatings and Linings, Protective: Atmospheric;
20、 STG 03 on Coatings and Linings, Protective: Immersion and Buried Service; and STG 43 on Transportation, Land. This standard is issued by NACE International under the auspices of STG 04. _ (1)The visual comparator mentioned in Appendix C is a molded plastic replica that illustrates various degrees o
21、f surface finishing for welds prior to coating or lining. Full-seam welds, skip welds, butt welds, lap welds, and others are depicted. For more information contact the NACE FirstService Department, 1440 South Creek Drive, Houston, TX 77084-4906. SP0178-2007 ii NACE International NACE International g
22、ratefully acknowledges the contributions of the following companies in the preparation of the welding samples and the fabrication of the die from which the plastic replicas have been molded: Ausimont USA, Inc.,(2)Thorofare, NJ CenterPoint Energy,(3)Houston, TX S.G. Pinney it is only intended to illu
23、strate 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
24、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 i
25、n 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
26、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 m (20 mil) thick applied as either a lining o
27、r 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, flame-spray
28、ed 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 deg
29、ree 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 Accessibility 3.1.1 All surfaces of the tank or vessel interior shall be readily accessible for surface preparation
30、 and lining application (see Figures A1 through A10, 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 (
31、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
32、A5, Appendix A). SP0178-2007 2 NACE International 3.2.2 Rivets shall not be used. 3.2.3 The use of internal bolted connections should be avoided to the fullest extent possible. 3.2.4 Continuous lap-welded joints may be used but are not preferred. For sheet lining material, this type of construction
33、may not be acceptable. 3.3 Connections 3.3.1 All connections to the tank or vessel shall be flanged. 3.3.2 Threaded connections should not be used in tanks and vessels operating in corrosive environments (see Figure A4, Appendix A). However, if threaded connections cannot be avoided in corrosive env
34、ironments, these parts shall be fabricated of corrosion-resistant materials, or constructed as shown in Figure A10, Appendix A. 3.3.2.1 CAUTION: Dissimilar metal (galvanic) corrosion occurs when, for example, an alloy is used to replace the steel bottom of a tank, or in a similar circumstance when a
35、lloy appurtenances must be part of the construction of a vessel. If a lining is then applied to the steel and part of the alloy (usually 150 to 610 mm 5.9 to 24 in.), any discontinuity in the lining exposes a small anode surface. Once corrosion starts, it progresses rapidly because of the large expo
36、sed alloy cathodic area to the much smaller anodic area. Without the lining, galvanic corrosion causes the steel to corrode at the weld area, but at a much slower rate. The recommended practice is to apply the lining to all of the alloy as well as the steel, thereby eliminating the possible occurren
37、ce of a large-cathode-to-small-anode surface. 3.3.3 Nozzle connections to be lined shall be as short as possible and be a minimum of 50 mm (2 in.) in diameter (see Figure A4, Appendix A). Connections less than 50 mm (2 in.) in diameter shall be suitably attached through a reducing flange (see Figure
38、 A10, Appendix A). When trowel-applied thick-film linings are required, additional nozzle inside diameter shall be allowed for lining thickness. 3.4 Appurtenances Inside the Tank or Vessel 3.4.1 The standard practices in Sections 3, 4, and 5 shall apply to any item to be installed inside a tank or v
39、essel that is to be lined. Such appurtenances include, but are not limited to, agitators, anti-swirl baffles, outlet connections, gauging devices, vortex breakers, and internal piping. 3.4.2 If appurtenances inside the tank or vessel, including nuts and bolts, cannot be lined, they shall be made of
40、corrosion-resistant materials. (CAUTION: See Paragraph 3.3.2.1.) 3.4.3 If bolted connections are necessary and cannot be made of corrosion-resistant materials, the mating surfaces shall be lined before assembly. Gaskets shall be used on mating surfaces and the sealing surfaces of nuts and bolts to p
41、rotect the lining. 3.4.4 Dissimilar metals shall be electrically isolated from the steel tank or vessel surface whenever possible. Where dissimilar metals are used, selection shall be such that the galvanic effect is minimized. Other corrosion mitigation methods may be required (see Figure A8, Appen
42、dix A). 3.4.5 Heating elements shall be offset from the tank or vessel surface to provide access for surface preparation, application, inspection, and cleaning. Elements shall be positioned so as not to damage the lining system. 3.5 Structural Reinforcement Members 3.5.1 Structural support members s
43、hould be installed on the exterior of the tank or vessel. However, if such members are installed internally, they shall be fabricated of simple shapes such as smooth, round bars or pipe for ease of applying the lining material. 3.5.2 The use of internal flanged connections, stiffening rings, reinfor
44、cement pads, angles, channels, I-beams, and other complex shapes should be avoided. If they must be installed internally, these members shall be fully welded and welds and sharp edges ground to a radius of at least 3.2 mm (0.13 in.) or as agreed between the tank or vessel fabricator, tank or vessel
45、owner, and lining applicator (see Figures A1 and A6, Appendix A). 3.6 Heat Sinks 3.6.1 Heated, forced curing of lining systems is often preferred if not specifically required. During tank or vessel design and fabrication, especially with field-erected units, consideration must be given to avoiding o
46、r minimizing heat sink areas. Such areas might include opposite saddles or support lugs, flat bottoms on foundations, and stiffening rings. 3.6.2 These situations may be addressed either by tank or vessel design or by construction or insulation of the foundation or supports. Another possible solutio
47、n is the use of temporary constructions, such as false floors or temporary shelters, to achieve uniform heating and curing. SP0178-2007 NACE International 3 _ Section 4: Fabrication Practices 4.1 All design practices in Section 3 shall apply to all fabrication. 4.2 All welding shall be continuous. I
48、ntermittent 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 over
