REHABILITATING SMALL DIAMETER PIPING SYSTEMS Author: Larry Gillanders ACE DuraFlo Systems lg@aceduraflo.com ABSTRACT The presentation will address the history of various methods of corrosion control associated with the use of thermo set resins such as epoxy linings using in-place restoration methods of piping systems covered under US Patents, # 7160574, #7517409 and #7858149, the present regulatory environment, overview of the actual application process, performance of epoxy linings, examination of previous applications, and who has chosen epoxy lining versus conventional re-piping methods. DoD related projects utilizing this method of corrosion control include applications at: (i) Fort Knox, KY for Administration and Readiness Buildings, (ii) Buckley AFB, Co, Hanger 81 for corrosion protection to radiant heating systems, (iii) USNS Dahl MSC Watson Class Vehicle Cargo Ship, for restoration of system critical lines for vessel propulsion system, (iv) Port Hueneme, CA - Naval Housing, restoration of hot and cold domestic water piping, (v) Fort MacArthur, San Pedro, CA Air Force Housing restoration of domestic water supply piping including in-situ pinhole and slab leak repairs. The general application of pipe restoration involves (i) an evaluation of the piping system, (ii) isolation of the system, (iii) draining the water from the pipes and air drying the pipes, iv) cleaning and profiling the interior of the pipes, (v) epoxy coating the pipes and finally, (vi) reassembly and testing the system. Keywords: pipe restoration, epoxy lining, corrosion, slab leak, pinhole leak. HISTORY In-situ or in-place rehabilitation of existing water mains and water related structures had its infancy in the United Kingdom in the 1970 s and has since developed into a reliable, cost effective and long term rehabilitation method for potable water pipes, water storage and distribution systems, with application now accepted world wide. In the United States, over the past 2 decades, methods have been commercially developed and patented, using epoxy barrier coating techniques that allow for the in-place rehabilitation of small diameter piping systems. The author is the co-inventor of 3 US issued patents covering various methods associated with in-place restoration of piping systems. US Patents, #7160574, #7517409 and #7858149
For this discussion, small diameter piping systems are defined as those comprised of pressurized pipes 2 and smaller in diameter. The result has been the commercialization of in-place rehabilitation of small diameter piping systems in single family homes, schools, hotels, hospitals and commercial buildings. This paper will assist the reader both from a historical and current developments perspective of the application of the in-place rehabilitation process. In-place rehabilitation, also called, pipe restoration, was developed as an alternative to conventional re-piping techniques, applied in a cost efficient manner to combat the effects of internal corrosion and other factors and to extend the life of a piping system. Pipe restoration using protective coatings such as epoxies and other thermoset resins, is now an economic alternative that can also be used to reduce the leaching of harmful metals into the drinking water supply, such as lead or copper. Figure 3 shows a restored galvanized pipe. REGULATORY PROCESS and APPROVALS This process of approving the epoxy lining material and process of application falls under three primary categories: Health, Physical Properties and Code Compliance. The lining material referred to as a coating has to be approved, safe for use with drinking water, meet industry standards for adhesion, durability, meet taste and odor tests if end use is intended to come in contact with drinking water and be applied to meet existing plumbing codes. In the US, standards have now been adopted by both major plumbing codes, IAPMO and ICC-ES relating to the process and coatings applied. IAPMO has provided for an Interim Guide Criteria for Internal Pipe Epoxy Barrier Coating Material for Application in Pressurized (Closed) Water Piping Systems. Originally adopted as IGC 2003, several updates have brought the Interim Guide Criteria to its current version, IGC 189-2008, which covers applications of epoxy lining to both metallic and non metallic piping systems. This standard provides minimum standards for the manufacture and performance of epoxy barrier coatings, mechanically applied to the interior surfaces of piping systems and includes referenced standards: ANSI/NSF 61, Drinking Water System Components - Health Effects, ASTM D 4541, Pull-Off Strength of Coating Using Portable Adhesion Testers, AWWA C210, Liquid-Epoxy Coating System for the Interior and Exterior of Steel Water Pipelines ICC-ES has adopted an Acceptance Criteria referred to as Internal Epoxy Coating Pipe Material Acceptance Criteria (AC 298), approved October 2005. This acceptance criteria was intended to establish the minimum criteria necessary for the use of a proprietary, mechanically mixed, blended, epoxy barrier coating that is mechanically applied to the interior of rigid pressurized water pipes. Codes and Referenced Standards include, 2003 International Plumbing Code, 2003 International Residential Code, International Code Council, ASTM D 4541-02, Standard Test Method for Pull-Off Strength of Coatings Using Portable Adhesion Testers, ASTM International, NSF 61-2004, Drinking Water System Components - Health Effects, National Sanitation Foundation and AWWA C210, Liquid-Epoxy Coating System for the Interior and Exterior of Steel Water Pipelines. AC 298 expanded on IAPMO s IGC 189 and addressed pipe cleaning standards, the effects of the lining material on flow rates, pressure loss and established evaluation report verification criteria. Table 1 shows the effects of the lining material on flow rates in small diameter pipes. In 2007, the first Evaluation Service Report, based on AC 298, was completed on the ACE DuraFlo, epipe patented method of pipe restoration by ICC-ES auditors which resulted in the issuance of Evaluation Report ESR#1390. - 2 -
IN-PLACE PIPE RESTORATION - BASICS While there are various approaches and methods used in the business, the writer has described in this paper the Methods and Systems developed and commercialized under the brand epipe by ACE DuraFlo protected under US Patents #7160574, #7517409 and # 7858149. Figures 1 and 2 show the general application of this process, which involves: (i) an evaluation of the piping system, (ii) isolation of the system, (iii) draining the water from the pipes and air drying the pipes, (iv) cleaning and profiling the interior of the pipes using a combination of a compressed air generator working simultaneously with a vacuum/collector, (v) application of a thermoset epoxy coating to the inside of the pipes and finally, (vi) reassembly and testing the system. Figure 2 illustrates the system set up. Step One - Problem Diagnosis Interview owner/site engineering staff regarding piping challenges. Evaluate local and on-site water quality. Determine extent of present damage to the wall thickness of the piping and overall integrity of the piping system, identify and assess leak size. Develop corrosion control proposal, including options for pipe and fitting replacement. Step Two - Project Planning and Setup Complete contract development with client. Complete equipment and supply delivery. Complete mechanical isolation of the piping system. Complete set up of hosing and equipment. Step Three Draining and Air Drying Pipes Map out piping systems. Isolations of piping systems are completed. The isolated areas to be restored are adapted to be connected to the restoration equipment. The isolated section is drained of water. Using moisture and oil free, hot compressed air, a flushing sequence is completed on the section to assure water is removed. Section is then dried using heated air. Length of drying sequence is determined by pipe type, diameter, length complexity, location and degree of corrosion contained within the piping system, if any. Inspections completed to assure a dry system. Step Four - Sanding Dried pipes are profiled using an abrasive agent. The abrasive medium is introduced into the piping system by the use of substantially moisture and oil free compressed air generator pushing the air and the abrasive agent through the pipe and operating simultaneously with the use of a vacuum/ collector at the opposite end. The abraded pipe, when viewed without magnification, should be free of all visible oil, grease, dirt, mill scale, and loose rust, prepared to a minimum NACE #3 Standard, as shown in Figure 4. Generally, evenly dispersed, very light shadows, streaks, and discolorations caused by stains of mill scale, rust and old coatings may remain on no more than 33 percent of the surface. Visual inspections are made to assure proper cleaning and profiling standards are achieved. - 3 -
An air flushing sequence and vacuum assist is completed to the piping section to evacuate any residuals left in the piping system. Step Five - Corrosion Control Epoxy Coating Piping section is heated with air to epoxy manufacturer s specification. Piping system is checked for leaks and determination of size of leaks. Epoxy is prepared and measured to manufacturer s specifications. Epoxy is injected into the piping system using heated compressed air. Allow the epoxy to cure to manufacturer s specifications. Step Six System Evaluation and Re-Assembly Remove all process application fittings. Examine pipe segments to assure appropriate coating coverage. Reconnect water system and water supply. Complete system checks, testing and evaluation of the integrity of the piping system, pressure test. Complete a water flush of system, according to manufacturer s specifications. Evaluate water flow and quality and complete pipe labeling. FIGURE 1-6 General Process Steps FIGURE 2 - System Layout - 4 -
FIGURE 3 - Galvanized Pipe Before and After Epoxy Coating FIGURE 4 Galvanized Pipe Surface Abraded to NACE #3 Standard TABLE 1- Flow Rates of Lined Pipes - 5 -
EPOXY LINING PERFORMANCE Long-term durability of an applied epoxy lining depends on various factors related to resin formulation and contractor performance, including: physical and chemical properties of the epoxy material proper surface preparation and cleanliness of pipe interiors prior to lining quality of site application, including the stability of the mix ratio and curing conditions and sensitivity of the epoxy material to application conditions In view of these factors and their various potential combinations, it is apparent that the behavior of lining systems could differ greatly even within an individual rehabilitation, making assessment of an open ended statement of long-term durability difficult. However, long-term durability of epoxy lining can be approached from a number of fronts: examination of known testing data, examination of coated samples of previous applications and the documented history of epoxy coating performance. ADHESION CORRELATION to LONGEVITY The adhesion of a coating is generally considered to be a good indicator of its longevity. A generally accepted adhesion value for "adequate" corrosion protection is 1000 psi. The greater a coating s adhesion to the substrate, the longer it will last. 1 The adhesion standards established by the American Water Works for epoxy lining pipes is 400 p.s.i. 2 Pull-off adhesion standards, for example, adopted by both major plumbing codes for epoxy lining products applied to metallic small diameter piping systems must be at least 2,500 p.s.i. demonstrating adhesion characteristics well in excess of the accepted AWWA standards. 3 EXAMINATION OF PREVIOUS APPLICATIONS The history of epoxy coatings is a history of adaptation and change in formulation as performance criteria became better known since the practice of epoxy lining of substrate for corrosion control became popular in the 1970 s. Leading the way in studies related to longevity, based on exhumed samples, has been the research conducted on behalf of the WRc, Water Research Centre of the UK. In conclusion of studies the WRc in Operational Guidelines and Code of Practice Manual for in situ epoxy resin lining states: In addition the good durability (in excess of 75 years) 4 and minimal reduction in hydraulic carrying capacity 5 of the epoxy resin process provide an excellent alternative to cement mortar for small diameter pipes and in particular those carrying soft water. 6 Further conclusions based on studies of some 82 exhumed pipe samples ranging in age from 4 days to 14 years lead to the following comments: The overall impression from the study is that epoxy linings are very durable and that with current formulations, application equipment and quality assurance procedures, a 30 to 50 year life can be readily achieved. 7 In Vancouver, Canada, a 1999, published paper, Epoxy Coating of Pipe Systems, focused partially on epoxy coating vs. conventional pipe replacement. General comments and summary findings in the report stated in part: Assuming that the epoxy was adequately applied and that it will then perform in a similar fashion to epoxy coatings applied by conventional methods, it is reasonable to expect the epoxy coating to remain intact for the life of the building (over 100 years). 8 The American Water Works Association engineering department in their assessment of rehabilitation technologies available for reducing or eliminating pipe failures, rates lining existing pipes to combat - 6 -
internal corrosion as high on the list of operational strategies that could be adopted by water utilities. They also provide a longevity rating of 30 to 50 years of extended life for a pipe that is internally coated using epoxy linings. 9 The presentor and co- inventors of the aforementioned patented processes have a progressive and related history of development and long-term application of epoxy coatings and other thermoset resins in numerous settings. An examination of this history dates back to 1990 when the predecessor-based epoxy was developed and applied. Epoxy coatings were applied in a variety of conditions and on a variety of substrates i.e.: steel, concrete, copper, PVC and PEX. Applications covered a wide spectrum of corrosion control projects including water storage tanks, pipe lines, manholes, storm drains, hatchery tanks and wastewater treatment systems. Protective coating projects have been completed for numerous civil agencies including the East Bay Municipal Utility District in the San Francisco area. The East Bay Municipal Utility District (EBMUD) supplies water and provides wastewater treatment for parts of Alameda and Contra Costa counties on the eastern side of San Francisco Bay in northern California. Approximately 1.3 million people are served by EBMUD's water system encompassing the major cities of Oakland and Berkeley. The wastewater system serves approximately 640,000 people in an 83-square-mile area of Alameda and Contra Costa counties along the Bay's east shore. Additionally, the predecessor formula was used to rehabilitate areas of an existing water treatment plant for the City of San Diego. Due to this projects exceptional pre-construction engineering and construction documentation and follow up inspections the project was used as a model project for an AwwaRF (American Water Works Association Research Foundation) research project studying the corrosion effects of enhanced coagulation on water treatment plant infrastructure. 10 In Southern California, as part of a study of protective coatings the County Sanitation District of Los Angeles County developed a test of protective coatings placed in a highly corrosive environment. The highly corrosive environment included a simulated wastewater facility with the coating material and substrate being exposed to a 10% sulfuric acid solution. After 1 year of evaluation, the epoxy coating was one of the few protective coatings to survive in this highly corrosive environment. 11 However, making the transition from the application of in-situ applied thermo set resins in larger diameter pipe systems to application in small diameter piping systems proved to not be without evolutionary changes. A 1997 research report completed by the Naval Research Laboratory reported the failure of a demonstration lining conducted at a Washington DC naval shore facility. 12 About 6 months after the lined pipes were returned to service, taps became partially or completely blocked with delaminated epoxy. Further analysis showed that a number of errors were associated with the demonstration application. A critical error in the work was that the dust from the blasting operation was left in the pipe, when the epoxy was added the dust and epoxy combined to form a viscous paste which entrained air and formed an excessively-thick, poorly adhering porous crust. In other areas blasting grit was found entrained in the epoxy. The application process overlooked a vacuum to assist in debris evacuation. In 2009, an epoxy lining application completed in California failed to meet specification, as a result of improper substrate preparation and inadequate removal of the spent abrasives which became entrained in the epoxy coating. 13 To overcome removal of dust and residual debris left behind in the cleaning process in small diameter pipe systems, applicators have added vacuum assist operations at the exit end of the piping system that work in conjunction with the blasting cleaning operation. In more recent history and in the direct application into small diameter potable water lines, sections of pipes from projects completed using the patented process has been examined. Long term monitoring of the performance of the epoxy lining that was placed in the potable water system of two Seattle, Washington hotels in early 2000 shows that the lining material is performing to specification. This is - 7 -
consistent with the long-term history of epoxy coatings found in studies completed by the Water Research Centre, WRc and published findings of the American Water Works Association. CONCLUSION - RESTORATION COMES OF AGE Overcoming application challenges in the past have helped moved the restoration of small diameter piping systems as an alternative to a re-pipe. Today, numerous consumer groups, engineers and installer groups have added in-place pipe restoration as one of their product choices. Engineers recognizing the benefits of combating corrosion and life extension of an existing piping system, especially when dealing with historical properties where access is limited, have chosen pipe restoration using the patented methods of application. Engineers at the high profile historic Willard Hotel located in the nation s capital, Washington DC, chose to epoxy line the domestic hot water piping system over a conventional re-piping for these reasons. Application of pipe restoration is not limited to buildings. British Petroleum engineers chose to protect the potable water piping system aboard the world s largest oil platform, Atlantis, located in the Gulf of Mexico. Recently in the UK, in-place pipe restoration methods have been added as alternatives to the replacement of lead service lines. The Army Corp of Engineers have utilized pipe restoration methods covered under the US patents #7160574, #7517409 and # 7858149 for epoxy lining of a variety of installed piping systems. Fort Knox, KY Administration and Readiness Buildings The restoration involved 6 Administration Buildings, hot and cold domestic water systems and the pipe restoration of 6 Readiness Buildings, boot wash systems. The project was a subcontract to B.L. Harbert International, completed under direct supervision of the Army Corps of Engineers. Project expedited with two crews and two equipment packages to meet specific timeline requirements of the client. Mr. Bradley C. Easley, Asst. Project Manager B.L. Harbert International IBCT Company Operations Facilities 2611 10th Armored Division Road Fort Knox, KY 40121 USNS Dahl MSC Watson Class Vehicle Cargo Ship, Cooling Lines The project involved the restoration of system critical lines for vessel propulsion system The project involved the restoration of critical steel cooling and fluid lines that were experiencing encrustation due to corrosion. USS Dahl is a 950 foot vessel in service since July 1999 and is one of the Military Sealift Command s 8 Watson Class vessels used for prepositioning of vehicles and equipment for the Navy, Defense Logistics Agency, Air Force and Marine Corps. The restored pipes are essential to the operation of critical components of the propulsion system and were not otherwise accessible for replacement or other remediation. - 8 -
Richard Gower Bayonne Dry Dock Military Ocean Terminal P.O. Box 240 Bayonne, New Jersey 07002-0240 Port Hueneme, CA - Naval Housing Project completed in multiple phases between June 2005 and June 2007. The project involved the restoration of the hot and cold domestic water piping systems. The project was a subcontract to Pride Industries whom are the plumbing and maintenance contractor for Naval Base, Ventura County. The restoration project was completed at Midway Estates Naval Housing located in Port Hueneme, CA. The multifamily housing project consisted of 32 multi-family buildings containing over 200 living units. Rosina D' Urso, Office Manager Pride Industries CBC Base Building 19, 43rd Street Port Hueneme, CA 93041 Fort MacArthur, San Pedro, CA Air Force Housing Project completed in multiple phases between April 2004 and February 2008 Restoration of domestic water supply piping, in-situ slab leak and pinhole leak repairs Project was a subcontract to Eastern Maintenance, the maintenance contractor for the Air Force Housing at the Fort MacArthur annex of the Los Angeles AFB. The housing was single family homes located in San Pedro, CA. The subcontractor had restored approximately 50 homes in this housing project on an 'as needed' basis whenever they experienced a slab leak. When a slab leak would occur, the subcontractor would restore the entire potable water system within the home as preventive maintenance to ensure the problem would not recur. Carlos Moroyogui, Maintenance Supervisor Eastern Maintenance and Services, Inc. Davis Air force Base-Tucson, AZ The project consists of a two story dorm with 120 units and the pipes in the attack readiness building. This 10 year old building had been experiencing pinhole leaks in its potable water piping system causing damage in the upper and lower units. The project started in November of 2010 and was completed in February of 2011. Diversified Maintenance Systems Ron Kuipers 4655 S Coach Dr., Tucson, Az 85743-9 -
Buckley Air Force Base, Hangar 801 - Denver, CO Restoration of in-slab radiant heating lines in aircraft hangar for Air National Guard. Project completed summer 2009 and required development of custom non-potable coating for coating long contiguous pipe runs and to assure compatibility with glycol product used in heating system. The project was a subcontract to provide in-place restoration of corroded steel radiant heating lines spanning the width of the entire hangar which were completely concealed in the reinforced concrete slab. The radiant system assures critical egress for military aircraft in/out of hangar during harsh Denver winter weather. Lining work completed on time and for a small fraction of other cost alternatives. Norm Reid, Project Manager HPE Heating & Plumbing Engineers, Inc. 715 Vallejo Street, Denver, CO 80204 REFERENCES 1 Guan S, PhD and Kennedy H, B.Sc., MBA. A Performance Evaluation of Internal Linings For Municipal Pipe. 1996 North American Corrosion Engineers, Denver, Colorado. 2 AWWA, American Water Works Association. C210-97 Liquid Epoxy Coating Systems for the Interior and Exterior of Steel Water Pipelines, Feb. 1998, Denver, Colorado. 3 Mills G and Associates. Laboratory Testing Data ACE DuraFlo, epipe, Humble Texas Dec 2001 4 Warren IC and Crathorne B. The Development of an Epoxy Resin Relining System for Potable Water Mains. Proc IWSA Conference Rehabilitation of Mains and Pipelines, Berlin 1989. Water Supply, pp151-155, 1990 5 Ewan VJ. A Study of the Effects of Relining On Leakage and Hydraulic Performance of Small Diameter Mains. External Report ER 185E, Water Research Centre (WRc), Swindon UK, 1986 6 Warren IC. In Situ Epoxy Resin Lining Operational Guidelines and Code of Practice. Water Research Centre ( WRc), Swindon, UK 1989 7 Protective Coatings Europe. Using Epoxy Linings to Rehabilitate Potable Water Systems, Pittsburgh, PA, March 1998 8 McCuaig J, P. Eng. Epoxy Coating of Pipe Systems, Vancouver, Canada 1999 9 AWWA, American Water Works Service Co. Inc., Engineering Department. Deteriorating Buried Infrastructure Management Challenges and Strategies, White Paper directed by USEPA, May 2002 10 Edwards M. Dr., Williams S.A., Fernandez E. Case study. Epoxy Lining, Otay treatment plant, City of San Diego, 2002 11 Render J.A. Hsi R., Esfandi E., Sydney R., Evaluation of Protective Coatings for Concrete. County Sanitation Districts of Los Angeles, Whittier California, August 1998 12 Brady Robert F, Jr., Adkins James D., Naval Research Laboratory, Control of Lead in Drinking Water. July 1997 13 Hernandez Eduardo, Schiff Associates, New Equipment Brings Progress into Focus., September 2009-10 -