August_AMP_Digital

ADVANCED MATERIALS & PROCESSES •

AUGUST 2014

Preventing

Corrosion Failures

orrosion is commonly defined as the

deterioration of a material or its prop-

erties because of a reaction with its en-

vironment. It is a natural process due to a high

energy state induced in metals and alloys during

refining, processing, and manufacturing. There-

fore, corrosion cannot be avoided but it can be

managed. The direct cost of corrosion in the U.S.

is estimated at $276 billion for 1998 (Fig. 1)

[1]

. In-

direct costs, such as loss of production, environ-

mental impacts, transportation disruptions,

injuries, and fatalities are estimated to be in the

same order of magnitude. Projections to June

2013 indicate that total corrosion costs, direct

and indirect, in the U.S. now exceed $1 trillion

dollars or roughly 6% of GDP. According to the

World Corrosion Organization, corrosion costs

are approximately 3-4% of the GDP of all indus-

trialized countries

[2]

Corrosion can cause dangerous and expen-

sive damage and failures of everything from

pipelines, bridges, and public buildings to vehi-

cles, ships, and airplanes, and from water and

wastewater systems to medical implants, com-

munication systems, and electronic devices.

However, there are well established methods to

prevent and control corrosion that can reduce or

eliminate its impact on public safety, the econ-

omy, and the environment. It is estimated

that 25-30% of the total direct cost

could be saved by using state-of-

the-art corrosion manage-

ment practices.

That said, the increas-

ing need for reliable

and inexpensive sources

of energy continually

pushes the develop-

ment and use of new

technologies. As with

any emerging technol-

ogy, additional corrosion

problems and potential

failures arise as a result of

the use of new materials in

new environments. A few recent

technologies that have been pro-

posed, matured, or introduced to the

market include: Deep offshore HT/HP oil and

gas production; CO

sequestration; fuel cells,

offshore wind energy, solar energy; new fuel

types; ultra-supercritical boilers; lightweight

structures; ultra-efficient car and jet engines;

geothermal energy; and nuclear waste disposal.

These and other new technologies push ma-

terials to withstand increasingly demanding con-

ditions as a result of higher temperatures and pres-

sures, and environments with greater corrosivity.

Therefore, the risks of new types of corrosion fail-

ures need to be considered along withmethods to

avoid them, as described in this article.

New corrosion challenges

Deep offshore HP/HT oil and gas wells:

In the

search for new reserves of energy, the oil and gas

industry is continually moving offshore to

deeper wells. Generally, increasing well depth

means increasing pressure and temperature.

High pressure/high temperature (HPHT) wells

have generally been considered wells in which

temperatures and pres-

sures at the bottomof the

well exceed 300°-350°F

(149°-177°C) and 10,000

psi (69 MPa). Conditions

exceeding 400°F (204°C)

and 20,000 psi (138 MPa) at the bottom hole

have been labeled variously as extreme HPHT

(xHPHT) and ultra HPHT. Additionally, a large

fraction of the world’s remaining oil reserves

consist of crude oil with either high H

S or CO

content that requires high quality, corrosion-re-

sistant materials. The same is true of gas fields

that are highly corrosive. Reliable materials for

deep well construction must have high strength

and corrosion resistance at high temperatures to

avoid potential failures.

Oil and gas developers need to leverage

every available technical solution to avoid fail-

ures andmaintain optimal production. However,

current corrosion resistant alloys (CRAs) suit-

able for harsh corrosion environments are ex-

pensive and can account for an appreciable

fraction of the cost of developing these re-

sources. As a result, some oil and gas fields are

not economical to develop.

Additionally, there is limited corrosion re-

sistance data available for CRAs at temperatures

that exceed ~450°F (232°C), and even less above

this temperature. In order to prevent corrosion

failures, fundamental materials characterization

and testing methods are needed to determine

the service limits of CRAs for localized corro-

sion attack and corrosion fatigue in the presence

of hydrogen; to develop new CRAs that are less

expensive to manufacture; and to develop sur-

face modification of lower-cost materials to im-

part required corrosion resistance.

Carbon dioxide capture and storage:

The

manmade atmospheric release of CO

during

Jose E. Ramirez

Christopher D.

Taylor

DNV GL – Oil & Gas

Dublin, Ohio

Modern

methods for

preventing and

controlling

corrosion can

reduce or

eliminate its

impact on

public safety,

the economy,

and the

environment.

Fig. 1 —

Direct corrosion

costs in five major

economic sectors

[1]

$20.1 billion

Government

14.6%

$17.6 billion

Production &

manufacturing

12.8% $47.9 billion

Utilities

34.7%

$29.7 billion

Transportation

21.5%

$22.6 billion

Infrastructure

16.4%