Newsletter - Issue III
(Fall 1998)
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1998 Fall Committee Meeting Notes
Company Profile
Information Exchange Corner
News From the Far East
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1998 Fall Committee Meeting Notes
(by Fu Huang)
The 1998 NACE Fall Meeting was held in Phoenix, Arizona from
September 13 to 18. Highlights of the T-8, Refinery Industry Corrosion
Group are:
Two state-of-the-art sessions were held. One was on Sulfidation
and the other was on On-Stream Inspection. There were 5-6 presentations
on each topic. A new CUI (Corrosion Under Insulation) inspection
method using pulsed eddy current technology was introduced. Another
presentation on Risk Based Inspection was also quite informative.
Task Group Updates:
T-8-16 Wet H2S Cracking - Review survey data.
T-8-19 polythionic Acid SCC - Working on format and areas of
coverage.
T-8-29 HF Unit Materials - Inputs from NACE T-8-20 for API-751
have been included in the latest revision.
T-8-21 Injection Facilities - The proposed report "Refinery
Injection System" was reviewed and discussed.
T-8-23 SOHIC Test method - A new SOHIC test method was proposed
on the round robin test program.
T-8-24 Prediction Tools for Sulfidation - This was the first
meeting for compiling and re-evaluating both existing and new data
on the subject of sulfidation.
T-8-25 Environmental Cracking - This was the first meeting for
addressing environmental cracking in refinery applications.
Corrosion Information Exchange- As always, this open forum for
discussion of materials, corrosion, inspection, and related topic
was the highlight of the week. One refinery reported their finding
and repair of cracks in the FCC regenerator to plenum weld. Another
company reported excessive corrosion of their HDT piping. There
was also a presentation about stainless steel condensate line
cracking at a Hydrogen Reforming Unit.
Special seminar on Corrosion in the Refinery Industry - This
was a 1 1/2 day training session. It was the second half of the
T-8 training. The first session was held in 1996. The plan is
to combine the two pilot sessions into one refinery corrosion
and materials training course and offers it at various locations
starting 1999. It would be a good training course for all inspectors
and materials engineers.
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Company Profile
Welding Services Inc.
(by George Lai)
In many large industrial plants, such as, power generating stations,
refinery and petrochemical plants, and pulp and paper mills, most
major plant equipment, such as boilers and pressure vessels, is
manufactured out of carbon steels or low alloy steels. After years
of operation, these large plant components have been subjected
to wall thinning or wastage due to corrosion and/or erosion attack
by either corrosive combustion environments or corrosive/erosive
processing streams. Replacement of these large components can
be financially costly and extended plant downtime. Refurbishment,
overhaul and upgrading of these boilers and processing vessels
by using advanced, automatic weld overlay technology has become
a preferred option for many plant operators to achieve a significant
life extension for these major components at a moderate cost.
These are some of the major services provided by Welding Services
Inc. (WSI), headquartered in Norcross (near Atlanta), Georgia.
WSI, founded about 20 years ago by two welding engineers, ex-General
Dynamic welding engineers, who started out by working pipe welding
and other specialty welding, is now a global specialty welding company,
currently employing about 130 permanent staff members and over 400
union boiler makers (welders) and providing services in the U.S.,
Canada, South America, Europe and Asia. The company is specialized
in advanced weld overlay and repair welding technologies to provide
for life extension of major industrial components and equipment
in a number of major industrial plants. These include power generation
plants (both fossil and nuclear plants), waste-to- energy boilers,
pulp and paper mills, refineries, and petrochemical and chemical
plants. Major services include field application of various weld
overlay alloys for corrosion and/or erosion protection for boilers,
reactor vessels, columns and towers using automatic weld overlay
systems; remote-controlled field welding and repair of critical
components in nuclear reactor plants; retubing of ethylene pyrolysis
and reformer furnaces, and other specialty welding projects, aiming
at helping plant operators in extending the service life of major
plant equipment.
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Information Exchange Corner
Methods for Removing Pyrophoric Iron Sulfide
(by Fu Huang)
A fire broke out on a crude tower at a Far East refinery during
a turnaround. Pyrophoric iron sulfide fire was the cause.
Deposits of iron sulfide are corrosion products which form in
sulfur containing environments deficient in oxygen. When opening
for service and exposing to air, the exothermic process of rapid
oxidation of the sulfides to oxides can generate a lot of heat.
Without proper control, concentrated heat could ignite and cause
a fire.
To minimize a pyrophoric fire, small equipment can be washed
down with water to disperse sulfide deposits and to quench the
heat. Removal of pyrophoric sulfides by chemical treatment before
a turnaround is more effective for major equipment. Options for
the chemical treatments are discussed below:
Acid Cleaning - This procedure pumps in an acid with some corrosion
inhibitor. The acid dissolves sulfide scale and releases hydrogen
sulfide gas. It is effective and inexpensive. Disposal of hydrogen
sulfide gas can be a problem. Corrosion can be a problem if the
system contains more than one alloy.
Acid plus hydrogen sulfide suppressant - Additional chemicals
are added to the acid solution to convert or scrub the hydrogen
sulfide gas. It is more expensive and less effective.
Chelating solutions - Specially formulated, high pH, chelating
solutions are quite effective in dissolving the sulfide deposits
without emitting hydrogen sulfide. This is an expensive application.
Oxidizing chemicals - Oxidizing chemicals convert sulfide to
oxide. Potassium Permanganate (KMnO4) is a better choice among
oxidants in that it can oxidize pyrophoric sulfide but is safe
to use and easy to apply. At 1-4% concentration, the solution
is harmless if it contacts skin. When the pyrophoric iron sulfide
is destroyed, the by-product is manganese dioxide. This material
is biologically inert and can be discharged directly to a waste
water facility.
The fire at the Far East Refinery was quickly put out and the
crude tower was blinded off. After careful evaluation of the above
mentioned options for chemical cleaning to remove iron sulfide,
it was decided that Potassium Permanganate would be the best choice.
Potassium Permanganate was added to the tower as a 1% solution.
At various intervals, samples were taken and checked for color.
The colors of the fresh KMnO4 and the spent MnO2 are purple and
brown respectively. If the color of the solution was brown, additional
KMnO4 was needed. The reaction was judged complete when the solution
color remained purple. The spent solution was sent directly to
the waste water treatment plant. It took approx. 12 hours to complete
the job.
The cost of Potassium Permanganate treatment is more expensive
than acid cleaning and traditional oxidizing agents such as sodium
hypochlorite or hydrogen peroxide. Nevertheless, it is less corrosive
to equipment than acid cleaning and it is a lot safer than other
oxidizing agents. After adding shorter treatment time and decreased
waste handling requirements, the Permanganate treatment can be
quite attractive when all things are considered.
The purpose of this article is information sharing. If you have
any interesting ideas, please send an article to the Secretary.
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News From the Far East
(by Dr. Tzyy-Ping Cheng)
The 1998 Annual Meeting and Technical Conference of the Corrosion
Engineering Association of the Republic of China was successfully
held on September 10 to 11 in a country club near Hsinchu City,
Taiwan. This year's meeting was cosponsored by Materials Research
Laboratories, National Central University, Lih Kang Industrial
Company, Taiwan Galvanizing Company, and National Science Council
of Executive Yuan. More than 120 members attended the conference,
and 40 papers were presented covering all aspects of corrosion
problems and anti-corrosion techniques. Owing to the awareness
of the increasing impact of pipeline corrosion, an invited talk
of "Corrosion Management of Buried Pipelines" had caught
members' high attention and intensive discussion. After a pleasant
and bountiful banquet, a laughter- abundant bingo game stress-relieved
the attendants and brought everyone a cheerful moment.
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