in the name of almighty Allah, the most merciful and beneficent

MEMBER

Name: sair ali khan

Course: CP Level-01

PROJECT TITLE

What is corrosion protection and corrosion control monitoring techniques?

PROJECT OVERVIEW

OBJECTIVE:

The objective of this project is to transfer the

crude oil from extraction point to the use

point via pipeline based CPS.

CC is for supervisory control and monitoring of the internal side of pipe lines parameters corrosion.

BLOCK DIAGRAM

CP

CIPS

PSP PCM

CC

COUPONS

PROBESRA

CATHODIC PROTECTION SYSTEM

Cathodic protection (CP) is a method of corrosion control that can be applied to buried and submerged metallic structures.

In most cases, effective corrosion protection & control of metals is obtained by combining two or more of these methods.

Corrosion protection should be considered at the design stage of a given facility or system.

Cathodic protection in its classical form cannot be used to protect surfaces exposed to the atmosphere.

The use of anodic metallic coatings such as zinc on steel (galvanizing).

First method, cathodic protection with galvanic anodes.

G.A uses the corthe rosion of an active metal, such as magnesium or zinc, to provide required electrical current.

This method, called sacrificial or galvanic anode cathodic.

In the second method, impressed current cathodic protection.

D.C current used to provide electrical current.

It is normally used in conjunction with coatings and can be considered as a secondary corrosion control technique.

The primary corrosion control method on any given structure is normally a coating system which can be between 50 and 99 % efficient depending upon age, type, method of installation.

Fig.

Underground metals

Fig.

MONITORING OF CPS

Close Interval Potential Survey (CIPS)Pipe To Soil Potential (PSP)Pipe Current Mapper (PCM)

CIPSClose interval survey is a survey method to provide detailed information on the potential difference between the pipeline and the soil.

CIPS is external corrosion of buried pipelines is made using pipe-to-soil potential measurements.

The Close Interval Potential Survey (CIPS) technique is aimed at assessing the CP effectiveness over the entire length of the pipeline, in between the permanent test stations.

CIPS are usually measured at fixed test points spaced between 1-5 km along a pipeline.

CIPS spacing depending on client requirement.

CIPS is reliable information about the CP status elsewhere along the pipeline.

CIPS test points indicate favorable data.

If the distance between the test points is decreased, the survey will provide more accurate data about CP conditions along the pipeline.

Cathodically protected pipelines are equipped with permanent test stations where electronic leads are attached to the pipeline to measure the pipe-to-soil potential.

The potentials measured at permanent test stations only originate from a small fraction of the total pipeline length.

One proposed rule of thumb estimates that the measured potential is associated with a relatively short length of pipeline - about 2x the depth of pipeline burial.

CIPS overcomes such problems by automatically recording, storing, calculating and displaying measurement data.

Fig. 1

Fig. 2

Advantages Of CIPS

Simple in principle and widely used.

Assessment extends along the entire length of the pipeline.

Complete pipeline right-of-way can be inspected as part of the walk along the pipeline.

Pipeline Current Mapper System (PCM)

The PCM+ Pipeline Current Mapper System by Radiodection consists of a portable transmitter and a hand-held receiver.

The transmitter is connected at the CPS station and applies a special signal to the pipeline.

The receiver locates this signal at distances up to 30 km (19 miles) to identify the position and depth of the pipe.

The PCM and its accessory equipment provide any pipeline technician with the latest in accurate.

Fast and reliable pipeline current mapping tools.

The location and measurement of pipeline corrosion using electromagnetic detection devices (Locators) must be linked with GIS (geographic information system) and GPS (Global Positioning System) to provide an accurate record of the condition of pipes and the position and time coordinates for post-mapping analysis.

This requirement is the basis of the PCM, which enables the pipeline technician to identify corrosion at an earlier stage and carry out preventative maintenance on pipelines to give them a longer life.

Radiodection Fig.

Fig.

About Radiodection

• PCM+ Receiver features Precision locator and PCM in one unit

• Unique features to improve data integrity (ASA, ACD, AGC, Depth of Cover)

• Quicker 3 second ACCA mapping• Record up to 1000 data records• Real time upload of mapped data via

Bluetooth to PDA or PC, also Integrates GPS data

• Downloadable analysis software for PDA and PC

• Integrates with standard GIS software

• 5key graph mapping modes including locate depth, current and phase

• Low power for full day survey• Backlight / Real sound• High power 150 Watt• 19 mile range @ 4Hz

Fig.

Quickly locate and measure pipeline coating faults

The location and measurement of pipeline corrosion using electromagnetic detection devices (Locators) are increasingly being linked with GIS systems and GPS information, to provide an accurate record of the condition of pipes and the position and time co-ordinates for post mapping analysis - this requirement is the basis of the PCM+.

Uses Of PCM

The PCM+ uses a powerful feature set consisting of Automatic Signal Attenuation (ASA), Advanced Current Direction (ACD) and Adaptive Ground Compensation (AGC).

The Pipeline Current Mapper (PCM) is used to conduct an ACCA (Alternating Current Coating Attenuation) survey.

The PCM utilizes a signal current that measures current

attenuation characteristics along with pipeline faults to other buried metallic structures.

Typically, a signal current is place on the pipeline at a rectifier.

Over the length of the pipe the current is measured and

charted.

Fig.

pipe-to-soil potential

The pipe-to-soil potential test has been established by corrosion engineers as a standard measurement technique in the evaluation of corrosion control and the degree of cathodic protection applied to buried metallic structures.

The copper sulphate half cell electrode used to contact the soil.

PSP measured between the pipeline and a reference electrode.

Unprotected buried steel will vary -0.30 to -0.80 volts.

The galvanic currents will flow through the soil between the anodic and the cathodic points.

If pipe-to-soil potentials along a pipeline were of equal values. Galvanic currents could not flow. No corrosion.

GC:Galvanic current occurs in the presence of two or more dissimilar metals in an electrolyte or saltwater environment.

Galvanic current is also known as electro galvanism.

Fig.

Fig.

PSP Example

For example, if the open circuit pipe-to-soil potential of an anodic point is -0.65 volt, then corrosion will be stopped if the potential of the cathodic point(s) is made more negative and equal to this value.

This is a basic criterion for the cathodic protection of a buried structure.

However, it would be impractical and almost impossible to determine the open circuit potential values and points of potential equalization along a pipeline, so corrosion engineers have established a second and more practical criterion for adequate cathodic protection.

It is generally accepted by the corrosion engineers that a structure will be under complete cathodic protection if the pipe-to-soil potential at all points on that structure is maintained at a minimum level of -0.85 volt.

This value represents over-protection in most instances, since the points of potential equalization, as pointed out above, is usually less negative than -0.80 volt.

This is the most practical and economical criterion to consider in testing for the existence of corrosion on any buried and coated pipeline.

PSP Testing

To make a pipe-to-soil test observation. Lead wire attached to the copper sulphate. Electrode is attached to the positive (+) post of the meter. A wire attached to the negative (-) post of the meter is

attached solidly to the pipe at any convenient point. This contact can be made by clipping directly to an above-

ground valve, fitting, riser, or even by attaching to a probe bar pushed into the ground to contact the pipe.

PSP Observation

Pipe-to-soil observations should be made whenever there is any question or any doubt that the structure may not be under full cathodic protection.

It is desirable to practice the of pipe-to-soil potentials at regular, say, six-month intervals to have assurance that no physical changes had previously been made that would upset the balance of the cathodic protection circuit.

This is for confirmation purposes, and to discover any changed condition which could result in corrosion damage to the structure.

Corrosion Control

Corrosion causes damages and loss of property if they have not controlled properly.

Monitoring of corrosion control:

Corrosion coupons. Probes (electrical probes). Residual analysis.

Corrosion Coupons

Corrosion Coupos or Weight Loss technique. Coupons are the primary techniques used for

monitoring. The is the best known and simplest of all corrosion

monitoring techniques. The method involves exposing a specimen of material

(the coupon) to a process environment for a given duration, then removing the specimen for analysis.

The basic measurement which is determined from corrosion coupons is weight loss; the weight loss taking place over the period of exposure being expressed as corrosion rate.

A specimen of test material to be used in a corrosion test.

Usually a metal strip or ring shaped to fit into a testing cell or between joints of drill pipe.

Rings, or coupons, are weighed before and after exposure, and weight loss is measured.

They are also examined for pits and cracks.

Corrosion products are analyzed to define the type of corrosion reaction.

Fig.

Coupon after exposure to corrosive environment

Fig

Metal Samples can make coupons in any size, shape, or material you need.

Coupons can be stenciled with alloy and sequence numbers for proper identification.

Monitoring program, coupons are exposed for a 90-day. Duration before being removed for a laboratory analysis. This gives basic corrosion rate measurements at a frequency

of four times per year. Therefore, coupon monitoring is most useful in

environments where corrosion rates do not significantly change over long time periods.

Advantages of Coupons

Advantages of weight loss coupons are that:

The technique is applicable to all environments - gases, liquids, solids/particulate flow.

Visual inspection can be undertaken.

Corrosion deposits can be observed and analyzed.

Weight loss can be readily determined and corrosion rate easily calculated.

Localized corrosion can be identified and measured.

Inhibitor performance can be easily assessed.

Probes (Electrical Reistance)

ER probes can be thought of as "electronic" corrosion techniques.

Electrical resistance probes are the primary techniques used for monitoring.

The electrical resistance (ER) technique is an "on-line" method of monitoring the rate of corrosion and the extent of total metal loss for any metallic equipment or structure.

The ER technique measures the effects of both the electrochemical and the mechanical components of corrosion such as erosion or cavitation.

It is the only on-line, instrumented technique applicable to virtually all types of corrosive environments.

The probe is electrically connected to the pipeline. ER probes provide a basic measurement of metal loss. Probe elements are made of a material similar to that of

pipeline. ER Probes are the most flexible of the electronic probes in

terms of their possible application.

Fig.

Principles of Operation:

The action of corrosion on the surface of the element produces a decrease in its cross-sectional area with a corresponding increase in its electrical resistance.

The increase in resistance can be related directly to metal loss and the metal loss as a function of time is by definition the corrosion rate.

The electrical resistance of a metal or alloy element is given by:

R= r. L/A where: L = Element length

A = Cross sectional arear = Specific resistance

Examples

Examples of situations where the ER approach is useful are:

• Oil/gas production and transmission systems

• Refinery/petrochemical process streams

• External surfaces of buried pipelines• Feed water systems• Flue gas stacks• Architectural structures

Fig.

Before after

ER Sensing Elements:

Sensing elements are available in a variety of geometric configurations, thicknesses, and alloy materials. Available element types are shown in Figure .

Metal Samples manufactures electrical resistance probes for corrosion monitoring in wire loop, tube loop, flush-mount, and cylindrical element.

Wire & Tube Loop: Wire and tube loop elements are Teflon or glass sealed.

Cylindrical:

Cylindrical elements are supplied in all-welded form.

Flush-Mount: Flush-mount elements can be provided with either glass or epoxy

seals.

Strip: Strip elements are commonly used in underground probes to

monitor the effectiveness of cathodic protection currents applied to the external surfaces of buried structures.

ER Probes AdvantagesER probes advantages They are applicable to all working environments gases, liquids, solids, particulate flows.

Direct corrosion rates can be obtained.

Probe remains installed in-line until operational life has been exhausted.

They respond quickly to corrosion upsets and can be used to trigger an alarm.

Uses Of Probes

Electrical resistance (ER) corrosion probes are commonly used in petroleum, chemical processing, and other environments where on-line corrosion rate readings are required.

Electrical resistance probes can be used in conductive systems, as well as non-conductive environments such as oil, gas, and atmosphere.

Residual Analysis Corrosion inhibitors are used to protect oil and gas

pipelines made of carbon steel that transport CO2 or H2S containing wet hydrocarbons.

The analysis of residual corrosion inhibitor concentration in production waters has been used for years to monitor the corrosion protection of oilfield systems.

The utility of an analytical procedure depends on the speed, accuracy, sensitivity, selectivity and precision of the method.

As the oilfields age, the water production volume increases while the oil production goes down.

The decreasing oil revenue, the cost of corrosion control becomes disproportionately high resulting in demands for lower cost of chemicals and services by the operating company.

Therefore, for a given corrosion inhibitor dosage, there is a need to determine the amounts of the active components present in the water and those in the oil phase as well as any loss to the solid surfaces.

48% internal corrosion occurs in pipeline.

NACE -96344 residual analyses

The paper describes the development of a fully automated instrumental procedure for testing residual corrosion inhibitors in production waters in the field.

Initial investigations were conducted in the laboratory to evaluate the suitability of ultraviolet and fluorescence spectrophotometric techniques to different of corrosion inhibitors.

Parameters for comparison included selectivity, sensitivity, speed, accuracy and precision of the methods under flowing conditions as in high performable liquid chromatography and as encountered in stand alone instruments.

For the field, the number of personnel, technical experience and proximity of the district Laboratory to the various leases were additional factors that were considered.

Although the development work included most of the nitrogen containing corrosion inhibitors (quaternary amines, imidazole’s, amides, etc.), the procedure for quaternary amines is used as the example and presented in detail.

ThE EnD

THANKS