Hydrocarbon Processing - February 2021 - 61

Maintenance
and Reliability
M. GREEN and R. RODRIGUEZ, CSNRI,
Riviera Beach, Florida

A compliant solution for repairing corroded
acid lines with composite materials
Composite materials have been utilized for the repair of
corroded or damaged piping in refineries, chemical plants
and other highly aggressive operating and production plants
around the world for decades. With advancements in available
technologies, along with organized industry standards, this upward trend has not only continued, but has required that composite technologies push the boundaries further.
Because of the demanding conditions found in most facilities, one area of need that has been growing is for an engineered
composite repair system (ECRS) that is compliant and effective
with highly acidic mediums found within piping systems. Many
requests for compatibility information between the pipe contents and the composite repair materials have been fielded from
the industry, with sulfuric acid in high concentrations being a
routine chemical in question. Due to the increasing demand for
ECRSs, new formulations and fibers for composite repair systems were reviewed for feasibility and tested for material properties to determine their effectiveness and performance.
Much research and subsequent testing programs were completed to develop a specialty polymer formulation that could
meet the needs of the industry, and meet qualification requirements, when used in conditions that are highly acidic in nature. This article will present the testing results, capabilities
and qualifications of this advanced ECRS.
Background. As ECRSs have gained more recognition and

acceptance as a reliable and beneficial repair alternative within
the refining and chemical processing industry, continued advancements in materials and capabilities have also allowed for a
greater range of usage-thanks in part to the development and
implementation of an ASME standard (ASME PCC-2 Article
4.1) in 2006, which provides industry a great deal of guidance
on material testing, qualification and design for composite repair systems. One such advancement has been in the area of
chemical compatibility, specifically for the use of composites
to be compatible with sulfuric acid at high concentrations. As
shown in FIG. 1, there are many common uses for sulfuric acid
across a variety of industries, so the demand for a repair system
that can be compatible to this aggressive acid is apparent.
The wide-reaching usage of sulfuric acid and its economic
impact are both major reasons why ECRSs are needed. Accord-

ing to Grand View Research, the global sulfuric acid market in
2016 was approximately $10.1 B, which is forecast to increase
to $13.45 B by 2025.
With such a vast market for this raw material, it is a clear indicator that a composite repair system with compatibility would
be highly beneficial. However, in many cases, the issue is not
with the chemical overall, but with the concentrations at which
it is utilized in facilities. Since composite repair systems are being
used routinely in the oil and gas industry, it was only natural that
compatibility-especially at higher concentrations-would be
one of the main criteria for ECRS development. While there
are some composite repair systems available that are compatible with sulfuric acid at lower concentrations, simply due to the
nature of most epoxy polymers, the higher concentrations and
temperatures above the standard ASTM testing conditions of
24°C (75°F) are routinely encountered in the field.
With this information, knowledge and experience in mind,
a program was developed to research and test for a new composite repair system that could withstand submersion in sulfuric acid at a 98% concentration level. Industry partners have
worked with the manufacturer to provide valuable insight into
the specific concentrations of concern, as well as the overall,
typical operating conditions experienced within their facilities. In addition, information was also provided for other repair alternatives, along with the reasons for developing the

Others 24%
Pulp/paper 1%
Paints/pigments 2%
Hydrofluoric acid 2%
Fibers 5%
Metal processing 10%
Phosphates 6%
Phosphate fertilizers 50%

FIG. 1. Common uses of sulfuric acid. Source: The Essential Chemical
Industry (online).
Hydrocarbon Processing | FEBRUARY 2021 61

Hydrocarbon Processing - February 2021

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