This article discusses the challenges involved with
coating contact, or “faying,” surfaces of steel
building components that are bolted together.
The use of certain zinc-rich primers is one successful
solution, provided the primers meet required
parameters for slip coefficient.
The heliport on a very large offshore structure
required complete coating removal and
replacement. The work could not be performed
during daylight hours because of a very busy and
crucial flight schedule, as well as safety concerns for
the workers from paint debris and metal loss. This
article describes the methods and materials used to
perform the work during nighttime hours. The
job was successfully completed in two weeks.
An excellent coating job can be ruined by
mechanical damage during shipping and
installation of the coated piece. Coating repairs can
be time-consuming, expensive, and may yield an
inferior coating job. This article provides
precautions to be taken to minimize coating
damage subsequent to initial coating.
Molybdenum-bearing stainless steels and nickel
alloys can experience catastrophic oxidation. This
occurs during oxidation of molybdenum-bearing
materials and is caused by the action of
molybdenum trioxide (MoO3) as an oxidation catalyst. This article explains the oxidation
phenomenon and suggests ways to prevent it.
This article describes the pipeline rehabilitation
program developed by the natural gas transmission
company in Colombia, South America. Part 1
presents the work accomplished to develop the
Effective Rehabilitation Plan (ERP). Part 2 discusses the ERP in detail, including results and accomplishments.
Wastewater treatment plant components generally
experience both atmospheric and immersion corrosion. Hydrogen sulfide (H2S), which is usually present, has wide-ranging effects in wastewater systems, most notably causing corrosion and odor problems. The corrosion problems can be mitigated by a combination of strategies including judicious selection and implementation of
emerging corrosion-resistant coatings.
There was a defect of severe micro-flow mark lines in
cathodic electrodeposited (CED) primer coating on car
components. This problem was highlighted after final painting. This article describes the tests performed to determine the root cause of the defect. Tests included a surface profile of the CED coating and the determination of the microstructure and nickel
content of the phosphate coating beneath the CED coating. The investigation identified the optimum concentration of nickel in the coating to refine phosphate grain size and create a unity
crystal aspect ratio. It also found that the triple point junction of phosphate crystals determines the porosity to provide a uniform CED coating surface finish.
Several factors cause deterioration of critical process
equipment in process plants. The options widely
utilized for restoration include conventional repair
or replacement. Nonmetallic composite materials
can be utilized as an option to restore equipment
integrity. This article discusses the material
degradation aspects in critical streams such as the
cooling water system and hydrocarbon pipelines at a
Saudi Arabian gas plant. Nonmetallic composite
coating materials play a vital role in corrosion
protection and life extension of core components.
Components of water treatment plants (WTPs) are
susceptible to corrosion from constant immersion in water
and proximity to chlorine. A case history of corrosion
problems and their treatment at an Army WTP is
presented. Solutions included using high micro-silica
restoration mortar and advanced coal tar epoxy coatings.
Epoxy/urethane coating systems are widely used for ships and offshore structures because of their excellent resistance to ultraviolet radiation and protection against corrosion. Recently, some of these coating systems used in Korea experienced premature failure. This work investigated the root cause of the failures using pH tests and Fourier transform infrared spectroscopy.
This article outlines the results of a long-term
pipeline integrity plan that was used to rehabilitate
large segments of a natural gas pipeline over the past
eight years. Part 1 of this article discussed the details to be followed in an effective rehabilitation plan to accomplish the goal of a well-maintained pipeline system.
An ethylene chlorotrifluoro-ethylene (ECTFE)
lining of a process vessel handling alkaline-based
fluids and active chlorine was examined after more
than 23 years of service. The examination and tests
showed that the ECTFE material was undamaged.
Test procedures, data evaluation, and
conclusions are presented.
Carbonated amine material, often called amine
blush, is the reaction product of the amine
functional curatives in epoxy paint with carbon
dioxide (CO2) and water vapor. This article explains the formation of amine blush and discusses factors controlled by the applicator and those controlled by the paint manufacturer.
A brick flue at a generating station was in need of
rehabilitation because of the spalling and cracking
of the brick. This caused a leakage of acid gases into the annulus. A typical flash coat system was not desired because of its relatively short life. A system of corrosion-resistant materials, which has shown excellent performance and durability, was chosen to make the repairs. The system consists of a combination of organic and ceramic-based lining materials. A case history is presented, with descriptions of the operating environment
and materials selection criteria.
Faced with serious concrete deterioration from
biogenic sulfide corrosion within collection systems,
engineers and municipalities are extending the
service life of wastewater conveyance structures with
the use of 100% solids polyamine systems designed
for hydrogen sulfide (H2S) permeation resistance. This article explains how sewer interceptors, manholes, and lift stations were protected using fluid-applied linings.