Overview

MISTRAS Overview

1

Overview

Improved RBI Analysis of Above Ground

Storage Tanks Through the Use of On

Stream Inspections

Sam Ternowchek

Mistras Group

2

Overview

Internal Inspections of Tank Floors is Expensive

Overview

Inspection Frequency Considerations

a) the nature of the product stored;

b) the results of visual maintenance checks;

c) corrosion allowances and corrosion rates;

d) corrosion prevention systems;

e) conditions at previous inspections;

f) the methods and materials of construction and

repair;

Overview

Inspection Frequency Considerations

g) the location of tanks;

h) the potential risk of air or water pollution;

i) leak detection systems;

j) change in operating mode

k) jurisdictional requirements;

l) changes in service

Overview

Determine Internal Inspection Interval

O

ORRisk Based Inspection

Interval Based on Fixed Time and/or Corrosion Rate

Internal Tank Assessment

Overview

Determined using the corrosion

rate procedures

Or, using the RBI procedures

API 653 Inspection Interval

6.4.2.3

6.4.2.4

Overview

Direct Measurements in API 653: Based on the sum of the product side and soil side bottom corrosion rates

Traditional approach for determining inspection

intervals in API 653

Tends to be a conservative approach because it is

based on the sum of corrosion rates

Inspection Interval Shorter then Necessary

False Sense of Security

Comparison

Overview

RBI Assessment with 10-Year Update Assessments based on API 580/581 as implemented in API 653: Based on direct measurements or conservative-provided estimates of the bottom corrosion rates

Tends to be considered realistic estimates because it is based on the maximum corrosion rate of the bottom

Provides a More Optimal Inspection Intervals

Assessments performed more often

Comparison

Overview

“If an RBI (Risk Based Inspection) assessment has been performed the maximum initial internal interval does not apply to tanks”

An owner/operator can establish the subsequent internal inspection interval using risk based inspection (RBI) procedures in accordance with API RP 580 and the additional requirements of API 653

API 653 Inspection Interval

Overview

The tank design and material of construction

Details about the foundation and surrounding area

Operational history

Inspection history

On Stream Inspections

Product characteristics

Etc.

Factors to Consider in a RBI Assessment

Overview

On Stream Tank Inspections

API 653 In-Service Inspection – Appendix C1.1

Advance NDT Techniques

Acoustic Emission to identify active corrosion on tank floor

Automated UT for corrosion mapping on tank shell (Liquid to

air preferential pitting)

Bulk wave UT for corrosion detection in critical zone

Pulsed Eddy Current and MWM for CUI

Overview

ADVANCE NON-INTRUSIVE SOLUTIONS

TO TANK INSPECTION

Overview

What is Acoustic Emission (AE)

Passive Listening Technique using Piezo Electric

Transducers

Overview

AE AE Sources from Corrosion

•Fracture Decohesion of

precipitation

Metal Dissolution

Thick oxide breakdown

Hydrogen evolution

Corrosion products

spalling

ACOUSTIC

EMISSIONActive Corrosion process

AE Sensor

Overview 16

Overview

Acoustic Sources Detected

Sources of interest:

Spalling of corrosion products.

Leak noise: flow interruption, or turbulence.

Extraneous noise to be removed: Roof and structural movement.

External and pipe-borne noise.

Condensation, particle impacts and valve

leakage.

Overview

Corrosion of Internal Zinc Anodes

• Internal sacrificial anodes

corrode in place on tank

floor.

• Zinc blocks can be large.

• Oilfield production tanks use

sacrificial anodes-very

active when coating has

failed, until zinc used, then

floor corrodes.

Emission from active anodes in a

180 foot diameter tank, 6 ft. x 3 ft. in

size, (30 in tank, 4/10/16)

Overview

Recommendations Matrix“Overall” Grade A B C D E

“PLD” Grade 5 5 2 (2) 1

A 5 5 2 (2) 1

B 4 4 2 2 1

. C 2 2 1 .5 .5

D 2 1 .5 .5 .5

E 1 1 .5 .5 .5

Clearly leaking tanks often unable to grade, (should be opened anyway).

Overview

3-D View of a “Bad” - “E” Grade

and a “Good” “A” Grade

Overview

FOLLOW UP INTERNAL INSPECTION

Overview

What is the Reliability: *

0

20

40

60

80

100

120

A B C D E

FU 1/2 Minimal damage: no repairs FU 3 Damage: some repairs

FU 4 Significant damage: major repair/new floor

Rela

tive

AE-grade

Follow-up results versus AE-grades, normalised per AE-gradepopulation of 157 tanks (Shell, Dow-Stade, DSM,

* P.van de Loo/Shell, B.Hermann/Dow, ECNDT 1998

Overview

Annular Ring UT Inspection

Overview

Long-Range Automated Ultrasonics

(LRUT) Annular Ring Test for Tanks

Gives condition information about critical annular area.

Test with Bulk Wave Ultrasonic

In-service test.

Manual or semi automatic

.

Targets

500m

m

Overview

LRUT Annular Ring Test

LRUT

Inspects critical area, ~20-30 cm.

Automated UT, Plan image.

Detects first edge of corrosion

40 m/day.

Indicative, not quantitative.

SHELL:

PLAN VIEW IMAGE SHOWING

SEVERE UNDERSIDE CORROSION

Overview

Tank Shell Surveys

Slide 27Copyright © 2014 JENTEK Sensors

All Rights Reserved.

MR-MWM-Array

Inspection of Corrosion

Through Protective

Barriers

JENTEK Sensors, Inc. 110-1 Clematis Avenue, Waltham, MA 02453-7013

www.jenteksensors.com

CUI – Corrosion Under Insulation

Slide 28Copyright © 2014 JENTEK Sensors

All Rights Reserved.

h (lift-off)

m(permeability)

MWM sensor

D (Thickness)

Paradigm shift in sensor design (first priority is

predictable response based on physics-based

modeling)

1. Sensors: MR-MWM®-Arrays 2. Next Generation 8200 GridStation®

Electronics

CUI - Technology Summary / Overview

Very low frequencies (deep penetration)

High data rates

Minimal drift

3. GridStation® Software using Hyperlattices™

Rapid, autonomous data analysis

Performs multivariate inverse method

(MIM) using precomputed databases

Defect Images

Performance Diagnostics

Noise Suppression

Real (Re)

Ima

gin

ary

(Im

)

Images

Analysis

MIM

Solve Multiple Unknown Problems

il/4

ScanDirection

Th

ickn

ess

Lif

t-O

ff

Overview

An Example Tank Management Program

“Plant Condition Monitoring Software” - PCMS

29

Overview

Background

• PCMS Captures all operating and design information as it relates to facility tankage

• PCMS evergreens the RBI process per tank circuit, taking into account

• Operating information

• Current corrosion rates

• Historical Inspections

• On Stream Inspections

• API 653 Visual Inspections recorded within PCMS

• Scheduling Flexibility (RBI/Corrosion/Fixed Based Interval)

Overview

TANK RBI SCREENING

• PCMS defines tank damage

mechanisms per mode

• PCMS automatically

screens which damage

mechanisms the tank is

susceptible to.

• PCMS calculates both base

and current Probability of

Failure

Overview

TANK RBI SCHEDULING• PCMS will notify inspector what damage mechanisms to inspect for

• PCMS generates an inspection plan per intrusive/extrusive inspection

types, and effective techniques to use to detect potential damage

mechanisms (customizable)

• User has option to schedule by fixed /corrosion/RBI based intervals

Overview

RBI MATRIX

• Tank circuits are plotted in the

RBI Matrix

• Plotting takes into

consideration POF and COF

(Probability and Consequence of

Failure)

• Consequence values are

configured per facility

• RBI Matrix is customizable

© 2012 MISTRAS GROUP, INC. ALL RIGHTS RESERVED. DISSEMINATION, UNAUTHORIZED USE AND/OR DUPLICATION NOT PERMITTED.

Example - Initial Internal Inspection Interval

Original Design

life > 10 years

25 years max

20 years max

for original High

rank

Risk Assessment

© 2012 MISTRAS GROUP, INC. ALL RIGHTS RESERVED. DISSEMINATION, UNAUTHORIZED USE AND/OR DUPLICATION NOT PERMITTED.

Extensions“Overall” Grade

A B C D E

“PLD” Grade

A 5 5 2 (2) 1

B 4 4 2 2 1

C 2 2 1 .5 .5

D 2 1 .5 .5 .5

E 1 1 .5 .5 .5

Overview

Benefits of RBI

Identify tanks which do not require immediate

internal inspection and repair – Saving MONEY

Determine the condition of damaged floors so that a

correct priority for internal maintenance may be set

Better scope of work when planning tank opening

Reduce down time when out of service

Do the above with little or no disruption to operations

Help prevent tank leakage

Overview

May lengthen or shorten the inspection interval

May result in additional focused inspections

Allows a company to focus its resources

On Stream Inspection Improve the accuracy of RBI

In Conclusion - RBI Assessments

Overview

QUESTIONS ????

Overview

MUCHAS GRACIAS

Sam.Ternowchek@mistrasgroup.com