Server maintenance is scheduled for Saturday, December 21st between 6am-10am CST.

During that time, parts of our website will be affected until maintenance is completed. Thank you for your patience.

Menu
Search
Filters
Close
Menu

Chemical Treatment To Mitigate Polythionic Acid SCC Without A Soda-Ash Wash: Laboratory And Plant Experience

Chemical Treatment To Mitigate Polythionic Acid SCC Without A Soda-Ash Wash: Laboratory And Plant Experience
Available for download

Different refiners have a variety of procedures in place for hydroprocessing reactor and reactor system shutdowns, depending on the scope of the work to be performed during the downtime. If activities are to be performed inside the reactor (e.g. inspection, maintenance, catalyst changeout, etc.) such that the reactor must be opened to air, shutdowns must include steps to address the various hazards. These same steps must also be applied to associated process equipment related to the reactor system susceptible to similar hazards and damage mechanisms. 

Product Number: 51322-17993-SG
Author: B.C. Rollins, K.J. Evans, N. Sutton, J. Esteban
Publication Date: 2022
Industries: Corrosion Monitoring and Control , Coatings
$0.00
$20.00
$20.00

A novel oxidative chemical treatment method is already being used to neutralize pyrophoric metal sulfides present in Hydroprocessing reactor systems. It is hypothesized that this treatment will similarly neutralize the iron sulfides which contribute to the formation of polythionic acids. A simple laboratory test has been developed to test the effectiveness of the chemical treatment. Previous experimental studies into polythionic acid stress corrosion cracking (PTASCC) have typically immersed stainless steel specimens in Saman’s solution, made by bubbling gaseous SO2 and H2S through the cell at controlled rates to produce a mixture of di-thionic through hexa-thionic acids along with sulfuric and sulfurous acids. In Saman’s solution, it can be difficult to obtain cracking even with the standard sensitizing heat treatments suggested in ASTM A2621. To circumvent these challenges, the current work uses standard U-bends (ASTM G302), coated with an air-sprayed suspension of iron sulfide powder. Specimens are suspended in saturated air (100% RH) at 50°C. Similarly, slow strain rate testing (SSRT) specimens were produced and tested using similar methods to identify the effect of exposure to FeS and various SCC mitigation and elimination treatments.

A novel oxidative chemical treatment method is already being used to neutralize pyrophoric metal sulfides present in Hydroprocessing reactor systems. It is hypothesized that this treatment will similarly neutralize the iron sulfides which contribute to the formation of polythionic acids. A simple laboratory test has been developed to test the effectiveness of the chemical treatment. Previous experimental studies into polythionic acid stress corrosion cracking (PTASCC) have typically immersed stainless steel specimens in Saman’s solution, made by bubbling gaseous SO2 and H2S through the cell at controlled rates to produce a mixture of di-thionic through hexa-thionic acids along with sulfuric and sulfurous acids. In Saman’s solution, it can be difficult to obtain cracking even with the standard sensitizing heat treatments suggested in ASTM A2621. To circumvent these challenges, the current work uses standard U-bends (ASTM G302), coated with an air-sprayed suspension of iron sulfide powder. Specimens are suspended in saturated air (100% RH) at 50°C. Similarly, slow strain rate testing (SSRT) specimens were produced and tested using similar methods to identify the effect of exposure to FeS and various SCC mitigation and elimination treatments.

Product tags
Also Purchased
Picture for Assessing Stress Corrosion Cracking Risks on Stainless Steel Piping and Equipment
Available for download

Assessing Stress Corrosion Cracking Risks on Stainless Steel Piping and Equipment

Product Number: 51317--8899-SG
ISBN: 8899 2017 CP
Author: Tina Tajalli
Publication Date: 2017
$20.00

This paper focuses on the risks of polythionic acid and chloride stress corrosion cracking, and reviews the risks from both internal process services and from external atmospheric and/or wet insulation conditions.
Picture for 98592 EFFECTS OF SENSITIZATION AND
Available for download

98592 EFFECTS OF SENSITIZATION AND SERVICE FLUID CHEMISTRY ON POLYTHIONIC ACID STRESS CORROSION CRACKING OF 18-8 STAINLESS STEELS

Product Number: 51300-98592-SG
$0.00
Picture for Effect of Carbon Content on Polythionic Acid Stress Corrosion Cracking Resistance for UNS S34751 with Extra Low Carbon Content
Available for download

Effect of Carbon Content on Polythionic Acid Stress Corrosion Cracking Resistance for UNS S34751 with Extra Low Carbon Content

Product Number: 51319-12783-SG
Author: Takahiro Osuki
Publication Date: 2019
$20.00

Polythionic Acid Stress Corrosion Cracking (PASCC) of conventional austenitic stainless steel is serious problem at desulfurization units in petroleum refinery.Post Weld Heat Treatment after welding and/or neutralization treatment using alkaline solution are required during each turn around to prevent PASCC according to NACE SP0170-2012.It has been known that proprietary version Type 347LN has superior PASCC resistance even if without Post Weld Heat Treatment (PWHT) compared with Type 347(H) or Type 321(H). Although the proprietary version Type 347LN is lower C content compare with standardized C content range (0.02%) to suppress precipitation of M23C6 carbide it is not reported that the effect of the slight variation of C content to PASCC resistance.Therefore the relationship between C content and PASCC resistance was investigated by using long term aged samples with simulated welding Heat Affected Zone.　As the result it was clarified that the strict control of C content less than 0.015% was effective to keep superior PASCC resistance under extra low C content range less than 0.02%.Key words:  Polythionic acid stress corrosion cracking Sensitization Proprietary version Type 347LN Hydroprocessing C content matching filler weld metalBest regardsTakahiro Osuki from NSSMC
Categories
Industry
Recently viewed
Popular tags
View all

Association for Materials Protection and Performance

© AMPP All Rights Reserved.
Membership Terms of Content Use
Contact Customer Support