Report on corrosion under insulation and

internal corrosion of TEG unit

Techno-Wings Co., Ltd.

March 07. 2018

Survey report from wall thickness measurement inspection, visual

inspection and fluid component analysis result of TEG

Ⅰ The types of corrosion thinning are described below

1. Corrosion under insulation of equipment nozzle

2. Corrosion reduction due to condensed water inside the equipment

manhole

3. Corrosion reduction of erosion on the back side of piping elbow for

two-phase flow

4.Corrosion reduction due to flash phenomenon

5. As an acceleration factor of corrosion thinning, it is moisture, Cl-.

Also, as moisture content increases, the iron content increases from the

analysis result.

Refer to DOC.07of the survey reference materials

3. Corrosion reduction of erosion on the back side of piping elbow

for two-phase flow

As shown in the corrosion loop of Doc.01, it occurred on the back

side of the piping elbow of rich glycol water removal equipment.

As a mechanism of two-phase flow,

・ ・ ・

・

・ ・ ・ ・

・ ・ ・ ・ ・

・ ・

Mist, water mass collision on the

back side of the elbow (1) It occurred mainly on the back side of the pipe

elbow.

(2)The temperature at which thinning occurs ranges

from 120 ° C to 250 ° C.

(4)Operating temperature does not occur because of

the low sensitivity of thinning in less than 100 ℃

piping.

(3)When the amount of moisture in the steam is high,

the mist collides with the wall of the pipe and causes

wall thickness reduction.

Schematic diagram of two-phase flow

Qualitative evaluation of the likelihood of damage caused by risk-based maintenance

Ⅰ Countermeasure for maintenance

As a risk-based assessment, which

showed a reduction measures in

maintenance.

Refer to the Maintenance Countermeasure (Ⅳ Countermeasure scheme)

The situation before the

maintenance countermeasure

Refer to Doc.10

insulation

N5

Impingement Attack

Corrosion under insulation:CUI

CUI CUICUI

CUI

CUI

CUICUI

50

50 50

5050

505050 50 50 80

50

50

80N9

N12B

N2 N11B

N12A

N1 N3 N6 N7 N8A N8B N8C N11A

2950

ID 9

50

50

IN

S.

9.5

TH

K

9820 V-160

M1

600

Schematic diagram "a"

“a”

Impingement attack has occurred at the exit of the internal nozzle with respect to N1.

CUI status of N1

Glass wool deteriorates, and they are seen to be wet.

CUI status of N7

The other inter-nozzle is presumed to be sound. Doc.02

Criteria for acceptable risk

Unacceptable risk

Negligible risk

ALARP region

As Low as Reasonably Practicable

It is necessary to

implement risk

reduction measures

and reduce risk as

much as possible

Examples of UK (Netherlands) figures

10-4 / year

10-6 / year

Doc.10