Metallurgy and Corrosion - · PDF fileMetallurgy and Corrosion Modeling, Materials, and...

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Metallurgy and Corrosion Modeling, Materials, and Monitoring

for Process Safety Management

Ned Niccolls

Senior Consulting Materials Engineer

Chevron Energy Technology Company

August, 2013

Richmond, CA

AIChE/SAChE Faculty Workshop on PSM

Metallurgy and Corrosion

Outline

Overview

PSM Context

Challenges and Realities

Example: “Deep Dive” of Wet H2S Cracking

Some Advanced Technologies and Opportunities

Appendix: Chevron Investigation Report for the August 6, 2012 fire

(more details available from the Chevron.com web site)

Overview: Modeling, Materials, and Monitoring to

Prevent Corrosion

Corrosion Prediction/Modeling

Inspection/

Monitoring

Materials

PSM Context

Greatest impact on safety and reliability was the serious adoption of

The Tenets of Operation.

The Tenets of Operation are based on two key principles:

"Do it safely or not at all" "There is always time to do it right"

Always...

1. Operate within design and environmental limits.

2. Operate in a safe and controlled condition.

3. Ensure safety devices are in place and functioning.

4. Follow safe work practices and procedures.

5. Meet or exceed customers’ requirements.

6. Maintain integrity of dedicated systems.

7. Comply with all applicable rules and regulations.

8. Address abnormal conditions.

9. Follow written procedures for high-risk or unusual situations.

10. Involve the right people in decisions that affect procedures and equipment.

Challenges and Realities

Typical Crude Distillation Seems pretty simple, but…..

Typical Crude Unit Overhead Large hardware, some not easily accessible…..

Typical Crude Distillation Unit Showing potential metallurgical damage mechanisms

Atmospheric

Column Vacuum

Column

Furnace Wastewater

Desalter

Preheaters

Corrosion Caustic Cracking

and Corrosion

Hot H2S

Corrosion

Graphitization

Naphthenic

Acid Corrosion

Nap. Acid

Hot H2S

Corrosion

Polythionic

Acid SCC

Polythionic

Acid SCC

Under Deposit

Corrosion

HCl/Chloride

Salt Corrosion

HCl/Chloride

Salt Corrosion Amine SCC

Wet H2S

“Low” Temp. Organic Acid

Corrosion

In the LER

• Brittle Fracture

• CUI

“Deeper Dive” Discussion:

Wet H2S (Hydrogen) Effects on Steels

950625-3

Where has hydrogen and steel been in the

news recently?

Bay Bridge Bolt Failure

“Deeper Dive” Discussion:

Wet H2S Effects on Steels

950625-3

SSC + HIC Damage

HIC Damage

G010570.jpg, G

010571.jpg

Wet H2S effects

Formation of Hydrogen Blisters by H2S Corrosion

G9901105

A clean steel surface normally catalyzes the combination of atomic hydrogen formed by corrosion to molecular hydrogen, but if H2S is the corrodant, the combination at the metal surface is greatly retarded and atomic hydrogen diffuses into the steel.

The buildup of an iron sulfide layer at the metal surface slows the rate of corrosion, and even if the steel has an internal defect, blistering may not occur. However, if cyanides are present along with the H2S, the ferrous sulfide layer may be dissolved, and hydrogen diffusion continues, creating high internal pressures at the defect, and as the steel eventually yields, producing blisters.

H0 + H0 + H2 (At Defect)

With FeS layer, reaction slows and blistering may not occur.

With cyanides present, FeS scale dissolves:

FeS + 6CN- Fe (CN)6 + S=

and corrosion continues, with formation of hydrogen blisters.

Effect of Changing Process Conditions on the Likelihood

for Wet H2S Cracking

New Vessel Process Upset

Crack Growth

Protective Scale

Crack Initiation

and Growth

Source: NACE Corrosion 1998, Paper 394

G9900115

Advanced Technology Opportunities

Corrosion Prediction/Modeling

Materials

Inspection/Monitoring

Corrosion Prediction/Modeling Flow regimes, surface conditions, kinetics, model verification….

Materials Surface engineered materials, advanced nonmetallics/composites, alloys

Corrosion Monitoring and Inspection

A number of technologies:

advanced corrosion probes

that penetrate into the

process….permanently

mounted external thickness

monitors… increasingly

wireless enabled….data

integration opportunities....

seeking capability for

“complete” inspection and

monitoring capability through

insulation

Opportunities

Collaboration of Academia, Government Laboratories, and Industry

– Example: Corrosion Under Insulation inspection work, and atomistic

corrosion modeling with Los Alamos

Tremendous opportunities within the Energy Sector

– For both “Traditional” and Alternative Energy spaces

Appendix:

Chevron Investigation Report for the August 6, 2012 Fire

Source: Richmond Refinery 4 Crude Unit Incident, August 6, 2012

(Report prepared by the CUSA Richmond Investigation Team, April 12, 2013)

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