Nestor Sequera Technical Manager SN Integrity Pty Ltd. September 06th 2018

Inspection Techniques to Detect Internal and External Corrosion on Insulated Piping

Know your enemy: What is CUI? Based on API RP-571 Definition Affected Materials Critical Factors Appearance of CUI damage Inspection Plan for CUI

NDT to detect CUI. Advantages and Limitations Conclusion

Agenda

What is CUI? Based on API RP 571*

Corrosion of piping, pressure vessels and structural components resulting from water trapped under

insulation or fireproofing.

Definition

* API RP 571: Damage Mechanisms Affecting Fixed Equipment in the Refining Industry.

Affected Materials

CS, low alloy steel, 300 & 400 Series SS and Duplex SS

What materials suffer from CUI?

Critical Factors (CFs)

Design of Insulation system: type, temp., environment

System Oper. Temperature: CRs increase with temp. up

to a level when any moisture vaporise quickly (160°C)

Present of Water

CFs influencing Corrosion Rate (CR):

NACE SP 198* classifies this CFs as:

effects of Water,

Contaminants, and

Temperature.

*Control of Corrosion under Thermal Insulation and Fireproofing Materials-A Systems Approach

Typical Appearance of CUI Damages • CS and low alloy steel shows loose, flaky scale covering the

affected section

• On 300, 400 series & Duplex SS insulated appearance will be localized pitting and corrosion

• 300 Series SS are also susceptible to SCC

Typical Appearance of CUI Damages

Typical Appearance of CUI Damages

Inspection Plan for CUI

A Plan should be developed to inspect and record earlier signs of CUI

Identifying / evaluating CUI Risks Assessment of piping failure likelihood

RBI

Mitigation

Monitoring

Inspection

Inspection Plan for CUI

Consequences

Inspection Plan for CUI

Notes:

* Where T > 160oC, susceptibility rating is set to ‘0’

** Coating condition awarded double points as this is the primary mitigation against CUI

2 3 4 5

22 - 2518 - 2113 - 179 - 12

1

Points Score

Start

Duplex Stainless Steel? - 2 pts

Condition Assessment of Insulated Item

2

3

4

5

Operating Temp (°C) Insulation Condition Coating Condition**Environment

+55 to +120

< -5

+121 to +160

-5 to +60

> +160 *

Poor

Good

Average

Unknown

Excellent

Marine

Semi-Industrial

Industrial

-

Rural

None

Good

Average

Unknown / Poor

Excellent

1

≤ 8

Sum of Assessment / Susceptibility Rating

* Stork Flow chart to assess Likelihood/probability of CUI.

Likelihood / Probability

Inspection Plan for CUI

RBI

Mitigation

Monitoring

Inspection

Type of Coating, Insulation

Methods /Techniques, Frequency and Number of CML’s /Locations

NDT to Detect CUI.

Advantages and Limitations

NDT to Detect CUI.

Advantages and Limitations

Conclusion

Corrosion on insulated piping is a real threat. Finding out the best NDT to ensure assets integrity requires an in-depth understanding of equipment and operational conditions to generate an RBI plan to maintain equipment integrity by cost-effective mitigations, monitoring and inspection activities.

Thanks for your attention.

Any questions