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Title: Strain corrosion cracking in rpm sewer piping

Abstract

Long term, aggressive environmental exposure can result in localized failure of large diameter, glass reinforced plastic mortar (RPM) piping. In order to evaluate the performance of the liner and glass reinforced matrix polyester resin, accelerated strain corrosion tests were performed on samples of RPM piping that had already experienced almost 15 years of service. To assess the sensitivity of RPM pipe to acidic environments and to correlate the fractography of the laboratory produced failures with the excavated crack, short segments of 8-inch and 48-inch diameter piping were statically loaded to produce various known surface strains. After preloading the specimens to fixed strain levels, these samples were then exposed to sulfuric acid solutions having pH values of 2.7 and 4.7 and monitored as a function of time until failure. The resulting lifetimes were related to initial surface strains and showed a decreasing logarithmic relationship. Fractographic examination of the excavated crack revealed the typical strain corrosion fractography of glass fibers after almost a 1000 hour exposure at 1.3 % strain; similar fractographic observations were obtained from failed laboratory samples. At shorter times, failure appeared to be overload in nature and exhibited little, if any, timedependent fracture features. Fractographic examination of the excavatedmore » crack strongly indicated that the crack had been present for a significant time. The extremely aggressive environment had totally dissolved the exposed glass reinforcement. Based on the laboratory strain corrosion performance, the nature of the contained cracking, and fractography of the failed surface, cracking of the excavated RPM pipe was believed to be the result of an early overload failure that subsequently propagated slowly via strain corrosion in an extremely aggressive environment.« less

Authors:
; ; ;  [1];  [2]
  1. Failure Analysis Associates, Inc., Menlo Park, CA (United States)
  2. Massachusetts Institute of Technology, Cambridge, MA (United States)
Publication Date:
OSTI Identifier:
143184
Report Number(s):
CONF-930246-
ISBN 0-87339-251-5; TRN: IM9413%%44
Resource Type:
Conference
Resource Relation:
Conference: Advanced composites `93: international conference on advanced composite materials (ICACM), Wollongong (Australia), 15-19 Feb 1993; Other Information: PBD: 1993; Related Information: Is Part Of Advanced composites 1993; Chandra, T. [ed.] [Univ. of Wollongong (Australia)]; Dhingra, A.K. [ed.] [DuPont, Wilmington, DE (United States)]; PB: 1464 p.
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; COMPOSITE MATERIALS; STRESS CORROSION; PLASTICS; GLASS; PIPES; FAILURES

Citation Formats

Hopkins, S W, Wachob, H F, Duffner, D H, Johnston, P R, and McGarry, F J. Strain corrosion cracking in rpm sewer piping. United States: N. p., 1993. Web.
Hopkins, S W, Wachob, H F, Duffner, D H, Johnston, P R, & McGarry, F J. Strain corrosion cracking in rpm sewer piping. United States.
Hopkins, S W, Wachob, H F, Duffner, D H, Johnston, P R, and McGarry, F J. Fri . "Strain corrosion cracking in rpm sewer piping". United States.
@article{osti_143184,
title = {Strain corrosion cracking in rpm sewer piping},
author = {Hopkins, S W and Wachob, H F and Duffner, D H and Johnston, P R and McGarry, F J},
abstractNote = {Long term, aggressive environmental exposure can result in localized failure of large diameter, glass reinforced plastic mortar (RPM) piping. In order to evaluate the performance of the liner and glass reinforced matrix polyester resin, accelerated strain corrosion tests were performed on samples of RPM piping that had already experienced almost 15 years of service. To assess the sensitivity of RPM pipe to acidic environments and to correlate the fractography of the laboratory produced failures with the excavated crack, short segments of 8-inch and 48-inch diameter piping were statically loaded to produce various known surface strains. After preloading the specimens to fixed strain levels, these samples were then exposed to sulfuric acid solutions having pH values of 2.7 and 4.7 and monitored as a function of time until failure. The resulting lifetimes were related to initial surface strains and showed a decreasing logarithmic relationship. Fractographic examination of the excavated crack revealed the typical strain corrosion fractography of glass fibers after almost a 1000 hour exposure at 1.3 % strain; similar fractographic observations were obtained from failed laboratory samples. At shorter times, failure appeared to be overload in nature and exhibited little, if any, timedependent fracture features. Fractographic examination of the excavated crack strongly indicated that the crack had been present for a significant time. The extremely aggressive environment had totally dissolved the exposed glass reinforcement. Based on the laboratory strain corrosion performance, the nature of the contained cracking, and fractography of the failed surface, cracking of the excavated RPM pipe was believed to be the result of an early overload failure that subsequently propagated slowly via strain corrosion in an extremely aggressive environment.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1993},
month = {12}
}

Conference:
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