Presentation

2.  Corrosion is the deterioration of metal that results from a
reaction with the environment which changes the iron
contained in pipe to iron oxide (rust).
Internal corrosion
 Internal corrosion occurs due to chemical attack on the
interior surface of the steel pipe from the commodities
being transported within the pipeline.
 In some cases, the corrosive liquids may be
contaminants such as water or other chemicals
entrained or suspended within the commodity being
transported.
What is corrosion

3. Internal Corrosion in Pipeline

4.  Natural phenomenon
 Fluid Corrosivity
 Flow Velocity
 Deposit Accumulation
 Water Accumulation
 Salt water
 H2S (acid gas with iron sulfide the by-product)
 CO2 (Major cause of produced gas corrosion)
 O2
 Bacteria (by products, acid produced)
 Other Impurities In Product
Causes

5. Corrosion control by the use of pigging
Corrosion control by the use of inhibitors
Corrosion control by the use of linings
Internal Corrosion Control Techniques

6.  In many circumstances an effective method of mitigating
galvanic corrosion on the internal surfaces of the piping is to
regularly remove the water and debris build up from the
system.
 Mechanical cleaning pigs are used to perform this function.
 The pigging schedule is frequently determined by monitoring
the data from corrosion coupons or probes installed in the
system and running pigs at different schedules until the most
effective routing can be achieved that results in an acceptable
corrosion rate with the minimum amount of pig runs.
Corrosion control by the use of pigging

7. Corrosion control by the use of pigging

8.  Inhibitors are chemical substances that slow or prevent
the corrosive chemical reaction and thus reduce
corrosion.
 Corrosion inhibitors frequently are chosen to mitigate
corrosion to an acceptable level if galvanic (water
induced) corrosion cannot be controlled by removal of
the water from the line with cleaning pigs.
 The inhibitor selected should not contaminate the product
being pumped or cause damage to refinery processes in
the case of crude oil.
Corrosion control by the use of inhibitors

9. • When added a corrosion inhibitor to a fluid or gas, it
decreases the corrosion rate of a metal or an alloy.
• The effectiveness, or corrosion inhibition efficiency, of
a corrosion inhibitor is a function of many factors like-
fluid composition, quantity of water, flow regime, etc. If
the correct inhibitor and quantity is selected then is
possible to achieve high, 90-99%, efficiency, but this
higher values shall be documented by laboratory and
field test.
• Some corrosion inhibitors are hexamine,
phenylenediamine, dimethylethanolamine, sodium
nitrite, cinnamaldehyde, condensation products of
aldehydes and amines (imines), chromates, nitrites,
phosphates, hydrazine, ascorbic acid, and others.
Corrosion inhibitors

10. • Nitrite is another anodic inhibitor. If anodic inhibitors
are used at very low concentration, they can actually
aggravate pitting corrosion, as they form a nonuniform
layer with local anodes.
• Zinc oxide is another example of a cathodic inhibitor,
which retards the corrosion by inhibiting the reduction
of water to hydrogen gas. As every oxidation requires a
reduction to occur at the same time it slows the
oxidation of the metal. As an alternative to the reduction
of water to form hydrogen, oxygen or nitrate can be
reduced.
Corrosion inhibitors

11. • A particular advantage of corrosion inhibition is that it
can be implemented or changed in situ without
disrupting a process.
• The major industries using corrosion inhibitors are the
oil and gas exploration and production industry, the
petroleum refining industry, the chemical industry,
heavy industrial manufacturing industry, water
treatment facilities, and the product additive industries.
• The largest consumption of corrosion inhibitors is in the
oil industry, particularly in the petroleum refining
industry.
Advantage of Corrosion inhibitors

12. • Corrosion inhibitor is classified into two major types
1) Oil soluble corrosion inhibitor ( for HSD)
2) Water soluble corrosion inhibitor ( for crude)
Classification of Corrosion Inhibitors

13.  Oil soluble inhibitor are used in many oil and gas
fields. It has high solubility with oil and mostly
added with high speed diesel products.
Oil soluble corrosion inhibitor (for HSD)

14.  This type of corrosion inhibitor is used with crude
product to protect the Internal metallic structure
from corrosive crude. Crude oil has many harmful
impurities that causes very fast rate of corrosion.
Water Soluble Corrosion Inhibitor (For Crude)

15. Inhibitor Deployment
Tank Inhibitor
Injected area
Pipeline

16.  Internal corrosion monitoring techniques includes:
 Residual Analysis
 Corrosion Coupons
 Electrical Probes
 Non Destructive Techniques
 In-Line Inspection
Monitoring Techniques

17.  To make sure the effectiveness of corrosion inhibitors
residual analysis are common method, in which water
sample re collected from all the crude storage tanks at
pumping station .
 Corrosion inhibitor residual analysis for any system are
established based on corrosion rate achieved.
 Residual analysis tested once in 5 year, or it depends on
previous result.
 If previous result was not as such aspect then it is tested
within 2 or 3 years.
Residual Analysis

18.  Corrosion coupons are a simple yet effective tool for
providing a quantitative estimation of corrosion rates
occurring in an operating system.
 They also provide a visual indication of the type of
corrosion which may be occurring in the monitored
system.
Corrosion Coupons
Corrosion Coupons

19. • Corrosion coupon is a piece of metal of predetermined
shape, size and surface area.
• It is a metal of similar chemical composition to the
process equipment.
• It has a uniform reproducible surface finish.
• It has a distinguishing serial number.
• It is exposed to the same corrosive medium as the process
facilities.
• It is exposed for a fixed period of time.
• It gives visual indication of the type of corrosion.
• It indicates the rate of corrosion
Corrosion Coupons

20. • Electrical corrosion probes include devices that can
detect the rate of corrosion in a variety of environments.
• Corrosion probes are used in deep core oil and gas
drilling.
• This corrosion-detecting devices are used to monitor the
amount of internal corrosion in oil tanks, platform pipes,
and deep core or subsea pipes.
Electrical Probes

21. Corrosion Probe Assembly

22. Non Destructive Techniques
• NDT testing plays most important role for internal
metallic structure through this techniques even we can
detect very small defects and flaws.
• Non Destructive testing consist of different testing
methods
1) Radiography Testing (R.T)
2) Ultrasonic's Testing (U.T)
3) Fluorescent Penetration Inspection (F.P.I)
4) Magnetic Particle Inspection (M.P.I)

23. Corrosion Probe Assembly

24. Corrosion Probe Assembly

25. Corrosion Probe Assembly

26. Corrosion Probe Assembly