1、NACE International 1 Item No. 24251NACE International Publication 08113 This Technical Committee Report has been prepared by NACE3 International Task Group (TG) 466,* “Identifying Corrosion Problems and Mitigation Strategies in Wastewater Systems.” Corrosion Problems and Renewal Technologies in Muni
2、cipal Wastewater Systems November 2013, NACE International This NACE International (NACE) technical committee report represents a consensus of those individual members who have reviewed this document, its scope, and provisions. Its acceptance does not in any respect preclude anyone from manufacturin
3、g, marketing, purchasing, or using products, processes, or procedures not included in this report. Nothing contained in this NACE report is to be construed as granting any right, by implication or otherwise, to manufacture, sell, or use in connection with any method, apparatus, or product covered by
4、 letters patent, or as indemnifying or protecting anyone against liability for infringement of letters patent. This report should in no way be interpreted as a restriction on the use of better procedures or materials not discussed herein. Neither is this report intended to apply in all cases relatin
5、g to the subject. Unpredictable circumstances may negate the usefulness of this report in specific instances. NACE assumes no responsibility for the interpretation or use of this report by other parties. Users of this NACE report are responsible for reviewing appropriate health, safety, environmenta
6、l, and regulatory documents and for determining their applicability in relation to this report prior to its use. This NACE report may not necessarily address all potential health and safety problems or environmental hazards associated with the use of materials, equipment, and/or operations detailed
7、or referred to within this report. Users of this NACE report are also responsible for establishing appropriate health, safety, and environmental protection practices, in consultation with appropriate regulatory authorities if necessary, to achieve compliance with any existing applicable regulatory r
8、equirements prior to the use of this report. CAUTIONARY NOTICE: The user is cautioned to obtain the latest edition of this report. NACE reports are subject to periodic review, and may be revised or withdrawn at any time without prior notice. NACE reports are automatically withdrawn if more than 10 y
9、ears old. Purchasers of NACE reports may receive current information on all NACE International publications by contacting the NACE FirstService Department, 1440 South Creek Drive, Houston, Texas 77084-4906 (telephone +1 281-228-6200). Foreword An increasing number of wastewater structures, systems,
10、and components are experiencing extreme corrosion and deterioration. Hydrogen sulfide (H2S) corrosion and microbiologically influenced corrosion (MIC) are principal contributors to the problems. The purpose of the report is to increase awareness of the problem of corrosion, and to provide a high-lev
11、el overview of the current state-of-the-practice and current state-of-the-art renewal technologies for rehabilitation, repair, and replacement of existing systems, structures, and components in wastewater systems. This report is intended for use by design engineers, decision makers, and other stakeh
12、olders in municipalities who are involved with the management, design, construction, maintenance, and/or operation of potable, sewer, and storm water systems, components, and structures. Chair Eric Dupr, Southern Trenchless Solutions, Houston, TX. NACE International 2 NACE Task Group (TG) 466, Ident
13、ifying Corrosion Problems and Mitigation Strategies in Wastewater Systems, prepared this technical committee report. TG 466 is administered by Specific Technology Group (STG) 08, Corrosion Management, and it is sponsored by STG 03, Coatings and Linings, ProtectiveImmersion and Buried Service. This t
14、echnical committee report is issued by NACE under the auspices of STG 08. NACE technical committee reports are intended to convey technical information or state-of-the-art knowledge regarding corrosion. In many cases, they discuss specific applications of corrosion mitigation technology, whether con
15、sidered successful or not. Statements used to convey this information are factual and are provided to the reader as input and guidance for consideration when applying this technology in the future. However, these statements are not intended to be recommendations for general application of this techn
16、ology, and must not be construed as such. Table of Contents Definitions 3 Section 1: Introduction . 4 1.1 Background 4 1.2 Purpose of This Report 4 1.3 RenewalRepair, Rehabilitation, and Replacement Terminology . 4 Section 2: Wastewater System Issues . 5 2.1 General Discussion 5 2.2 Summary of Waste
17、water Issues 6 Section 3: Hydrogen Sulfide Corrosion 7 3.1 Significance of Hydrogen Sulfide Corrosion in Wastewater Systems . 7 3.2 Basic Mechanisms of Hydrogen Sulfide Corrosion 7 3.2.1 Sulfuric Acid Corrosion 7 3.2.2 Direct Hydrogen Sulfide Attack of Metals 9 3.3 Factors Affecting Corrosion 9 3.4
18、Major Hydrogen Sulfide Corrosion Target Areas . 10 3.4.1 Gravity Sewers 11 3.4.2 Pump Stations and Force Mains . 11 3.4.3 Wastewater Treatment Facilities . 12 3.5 Approaches for Identifying Existing or Potential Corrosion Problems 12 Section 4: Characteristics of Wastewater and Renewal Technologies
19、14 4.1 Sewer Mains 14 4.2 Sewer Laterals . 22 4.3 Manholes . 26 4.4 Ancillary Structures 29 4.5 Force Mains . 30 Section 5: Additional Technology Considerations 33 5.1 Construction and Life-Cycle Costs . 33 5.2 Description of Selected Current, Emerging, and Novel Technologies 34 5.3 Long-Term Perfor
20、mance and Testing 41 5.4 Other Typical Design Considerations . 41 5.5 Decision Support for Choice of Rehabilitation vs. Replacement, and Choice of Rehabilitation Systems . 43 Section 6: Cross-Cutting Innovations . 43 6.1 New Materials 44 6.2 Wastewater Innovations . 44 6.3 Decision Support 44 6.4 Ac
21、celerating Adoption of New Technologies 45 6.5 Observations on Successful Programs 47 Section 7: Brief Overview of Condition Assessment 48 7.1 Brief General Description of Condition Assessment 48 7.2 Dynamics of Wastewater System Failure . 48 7.3 Inspection Technologies 49 7.4 Gaps in Current Knowle
22、dge . 49 Section 8: Summary . 51 References. 51 Additional Resources . 52 Appendix A: Selected NACE/SSPC Standards for Surface Preparation of Infrastructures 52 NACE International 3 Definitions Access pits or insertion pits: Pits to allow proper access for equipment or personnel to enter a buried pi
23、pe or structure. Comminutor: A machine that breaks up solids. Cured-in-place pipe (CIPP): A hollow cylinder consisting of a polyester- and/or glass-reinforced plastic fabric tube with cured thermosetting resin. The CIPP is formed within an existing pipe and takes the shape of the pipe. Fines: Partic
24、les smaller than average in a mixture of particles varying in size. Folded pipe: Pipe that has been manufactured and calibrated in a round shape, and then subsequently cooled and deformed into a folded shape for insertion into the existing pipe. Formed pipe: A folded pipe that has been inserted into
25、 an existing pipe and expanded with steam heat and pressure and, if required by the manufacturer, with a squeegee device or pig to provide a close fit with the existing pipe. Fully deteriorated pipe: The existing pipe is not structurally sound and cannot support soil and live loads, or it is expecte
26、d to reach this condition over the design life of any rehabilitation. This condition is evident when sections of the existing pipe are missing, the existing pipe has lost its original shape, or the existing pipe has corroded because of the effects of fluid, the atmosphere, or soil. Headworks: A part
27、 of the wastewater treatment structure that separates heavy solids from the liquid portion of the waste coming into the plant. Inverts: Channels that funnel the waste water between the incoming and outgoing pipes connected at the manholes. Launder: An inclined channel or trough for the conveyance of
28、 a liquid, such as for water in mining and construction engineering or for molten metal. Open cut: Excavation from the surface to install or rehabilitate a buried utility. Partially deteriorated pipe: The existing pipe can support the soil and surcharge loads throughout the design life of the rehabi
29、litated pipe, but the soil adjacent to the existing pipe is expected to provide adequate side support. Pipe bursting: The breaking up of existing pipe and pushing it into the surrounding soil by passing a bursting or splitting device through it, while pulling a replacement pipe in behind the burstin
30、g head. Pipe eating: A process used for the trenchless replacement of undersized or damaged sewers, as well as for new installation, by the use of a microtunnelling machine. The machine crushes the existing pipe material with a built-in crusher and also permits realignment and upsizing of the sewer.
31、 Renewal: The application of infrastructure repair, rehabilitation, and replacement technologies to return functionality to a wastewater collection system. Repair: A technique that is used when the existing pipe is structurally sound, provides acceptable flow capacity, and can serve as the support o
32、r host of the repair method. Rehabilitation: Internal coatings, sealants, and linings used to extend operational life and restore much or all of the pipes hydraulic and structural functionality. Replacement: An existing pipe is usually replaced when it is severely deteriorated, collapsed, or increas
33、ed flow capacity is needed. Septage: A void that allows a leak in the wastewater system. Sliplining: The installation of a smaller-diameter replacement pipe inside an existing pipe, leaving an annular gap between the two. The replacement pipe can be continuous or made up of discrete segment lengths.
34、 Surcharging: A breach of containment caused by the wastewater collection system being over its capacity. NACE International 4 Trenchless technology: A family of techniques that allow installation and rehabilitation of buried utilities without the need to excavate a continuous trench to access the u
35、tility. Weir: A device that regulates the volume of liquid passing into the next chamber at a desired limit or rate. Section 1: Introduction 1.1 Background The phrase out of sight and out of mind is a synopsis of the current condition of wastewater collection systems throughout the United States. Ma
36、ny times, public attention is only given to wastewater systems when there is a catastrophic infrastructure failure, a significant release of waste water to the environment, or simply when someone cannot flush their toilet. The wastewater system in the U.S. is getting old; 2% is more than 50 years ol
37、d, 68% is more than 25 years old.1 It is clearly apparent there is a serious problem when the American Society of Civil Engineers (ASCE)(1) has rated the U.S. wastewater infrastructure with a grade of D in the latest (2013) infrastructure report card2only a slight improvement from its grade of D- in
38、 the last assessment in 2009. The Water Environmental Research Foundation (WERF)(2) estimates that wastewater utilities purveyors spend approximately $4.2 billion annually to rehabilitate sanitary pipelines alone. Municipal and state budgets are becoming more constrained and less able to maintain/su
39、stain these deteriorating wastewater systems. Doing more with less has become a common theme in many asset management programs nationwide. According to the U.S. EPA(3) 2009 Rehabilitation of Wastewater Collection and Water Distribution Systems report,1“we stand at the dawn of the replacement era” an
40、d timing is vital to address current and future challenges now. 1.2 Purpose of This Report The purpose and scope of this report is to provide: General information and an overview about the process of H2S corrosion, the microbiologically influenced corrosion (MIC) process, typical major corrosion tar
41、get areas, and basic approaches for identifying existing or potential corrosion problems in wastewater systems, and The status of the most recent renewal technologies available for wastewater systems using current, emerging, and novel methods. This report is not intended to address all types of acti
42、vities used for the development and implementation of a renewal construction project in wastewater system infrastructures. Examples of exempted activities include (but are not limited to) monitoring, quality assurance/quality control (QA/QC), testing, and project-specific and detailed information ab
43、out condition assessment and inspection. The reader may consult the reference section of this report for sources of detailed information. Complete descriptions of mechanisms or complete solutions for predicting or solving problems in the wastewater industry are outside the scope of this report. The
44、emphasis of the report is on trenchless technologies, which do not require full excavation of the buried asset to carry out the work. These technologies have made a significant penetration into the U.S. market, with estimates of the proportion of rehabilitation work carried out using trenchless tech
45、niques ranging up to 70% in the sewer sector. There is still considerable room for improvement in existing trenchless technologies and in the development of new trenchless technologies. Such improvements or new technologies offer the opportunity to increase the return on investment in system rehabil
46、itation and to allow utilities and local governments to fix larger portions of their systems within current funding limits. A secondary benefit is to increase the political and public will to spend additional money on fixing this problem. 1.3 Renewal Repair, Rehabilitation, and Replacement Terminolo
47、gy The terminology used in connection with infrastructure maintenance and renewal is not fully standardized, which can lead to some overlapping of terminology and potential confusion among those trying to gain an overall understanding of the industrys (1) American Society of Civil Engineers (ASCE),
48、1801 Alexander Bell Drive, Reston, VA 20191. (2) Water Environmental Research Foundation (WERF), 635 Slaters Lane, Suite G-110, Alexandria, VA 22314. (3) Environmental Protection Agency (EPA), Ariel Rios Building, 1200 Pennsylvania Avenue NW, Washington, DC 20460. NACE International 5 structure. In
49、this report, system renewal refers to the ultimate goal, while repair, rehabilitation, and replacement are methods to maintain system performance and extend its life to keep the system functioning at an acceptable level and with minimum life-cycle costs for the foreseeable future. Individually, the terms repair, rehabilitation, and replacement, as used in this report, signify the following: Repair actions are used either to restore the wastewater system to an operating condition or to deal with localized deterioration. The repair may be temporary until a more compl
