Ballot ID: Action item Reference Number: Addition of common causes and susceptibility diagram to API RP 581, 3rd Edition, Section 12

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1 Ballot ID: Action item Reference Number: Title Addition of common causes and susceptibility diagram to API RP 581, 3rd Edition, Section 12 Date: October 2018 Purpose: Revision: Impact: Rationale: Technical Reference(s): Calculation Change Provide an update regarding ClSCC likelihood of failure equations and specifically factors influencing susceptibility R3 Addition of new susceptibility diagram (Figure 12.2) and relevant terminologies ClSCC can occur in environments where liquid water is present and chlorides can reach sufficient levels of concentration. Oxygen is also likely to have an impact on the susceptibility. 1. ASTM STP No. 264, Report on Stress-Corrosion Cracking of Austenitic Chromium-Nickel Stainless Steels (1960) 2. Rideout, P.S., Abstract 67, Corrosion Conference Scharfstein, L.R. & Brindley, W.F., Corrosion, 14, N12, Rion, W.C., Industrial & Engineering Chemistry, 49, 73A (March 1957) If the proposed change includes a change in calculation result, include a sensitivity study, a sample showing existing and proposed calculation changes or a MS Excel file showing the differences in the existing and proposed models Attachments

2 Primary Name: Murry Funderburg Sponsor Company: Phone: Cosponsor(s): Shervin Maleki TWI Tracking Status Submitted to Task Group Submitted to SCI Submitted to Master Editor Date Resolution Date Resolution Date Resolution

3 Proposed Changes and / or Wording (attach additional documentation after this point) Current 3 rd edition susceptibility table for comparison with ballot. Table 12.2 Susceptibility to Cracking ClSCC Temperature ( F) ph 10 Susceptibility to Cracking as a Function of Chloride ion (ppm) ,000 > 1,000 <100 Low Low Low Medium > Low Medium Medium High > Medium Medium High High > Medium High High High >300 High High High High Temperature ( F) ph > 10 Susceptibility to Cracking as a Function of Chloride ion (ppm) ,000 > 1,000 <100 None None None None > Low Low Low Low > Low Low Low Medium > 300 Medium Medium Medium High

4 Comparison of new graph with 3 rd edition susceptibilities.

5 12 ClSCCcc Damage Factor Chloride Stress Corrosion Cracking 12.1 Scope The DF calculation for components subject to Chloride Stress Corrosion Cracking (CLSCCClSCC) is covered in this section Description of Damage ClLSCC of austenitic stainless steels can occur in a chloride -containing aqueous environment. The susceptibility to ClLSCC is dependent on the concentration of the chloride ions, the temperature, and other factors outlined in the basic data Table It should be emphasized that the chloride concentration in water within wetting and drying conditions can be higher than the concentration measured in the bulk solution due to partial water vaporization leading concentration. Such vaporization and can increase ClLSCC susceptibility. Chlorides are found in many processes. The following factors are major influences on the likelihoodprobability of cchloride-containing solutions to cause ClSCC. a) Liquid water must be present. b) ph and temperature are the most influential factors in ClSCC. c) Below a temperature of 25 C (77 F), cracking is virtually unknown. But extremes of Cl concentration, stress, and/or ph havecan caused cracking. d) ClSCC is more likely to occur at metal temperatures above 60 C (140 F). e) Above 150 C (302 F), it has been generally accepted that liquid water is not present unless the system is under pressure. f) Below a ph of ~2.5, the material etal corrodes/pits rather than. Ccracking alone is not usuallyas the cause of failure. g) Above a ph of ~10.5, only extremely high Cl concentrations, in the presence of with oxygen O2 present plusand elevatedhigh stresses and temperature are reportedmay to cause experience cracking. In these conditions, this cracking may be better characterized asonsidered to be caustic cracking. h) In industrial processes, chlorides even at the ppm level may concentrate even in low bulk process Cl ppm concentrations.. i) In laboratory tests, concentrations of 10 ppm Cl are sufficient to influence cracking in higher temperature solutions at ph of 6 and below. Oxygen may also increase the likelihood of ClSCC in these regions. j) Higher chloride content can influence the tendency toward cracking or not cracking in the less extreme regions of ph and temperature. k) In the High likelihoodsusceptibility region of ph and temperature, a very lowfew concentrations of ppm of chlorides may result in can causecl cracking. Austenitic stainless steels should not be used in this region. CLSCC is more likely to occur at metal temperatures above 66 C (150 F). Examples of common sources of chlorides in refineries and petrochemical plants are as follows: a) a) Chloride salts from crude oil, produced water, and ballast water b) b) Water condensed from a process stream (process water) c) c) Boiler feedwater and stripping system d) d) Catalyst e) e) Insulation f) f) Residue from hydrotest water and other manufacturing operations g) g) Fumes from chemicals containing either organic or inorganic chlorides

6 CLSCCClSCC may occur during in-service or shutdown periods, if chloride- containing solutions are present at, especially at temperatures greater thanabove 6660 C (1450 F). In addition, internal CLSCCClSCC maycan occur internally (for example, byas a result of exposure to wash-up water or fire water). CLSCCClSCC is typically transgranular and highly branched. The greatest susceptibility to CLSCCClSCC is exhibited by austenitic stainless steels with a nickel content of 8% Ni content (300 series e.g., Type 300 series, 304, 316 stainless steel, etc.). Greater resistance to ClSCC is generally shown by alloys of eitherexperienced in material with lower or higher nickel contents8% Ni contents. Duplex stainless steels with low nickel contents are generally immunemore resistant to CLSCCClSCC, as are alloys with greater than 42% nickelni Screening Criteria If all of the following are true, thent the component should be evaluated for susceptibility to CLSCCClSCC cracking if all of the following conditions exist: a) a) The component s material of construction is an austenitic stainless steel b) b) The component is exposed, or potentially exposed, to chlorides and water. aalso considering upsets, and hydrotest water remaining in a component, and cooling tower drift (consider both under insulation and process conditions. c) c) Presence of liquid water d) The operating temperature is between C (75 F) and C (345 F)The operating temperature is above 38 C (100 F) and a ph > 2.5 and < 10.5 (If ph is < 2.5, go to HCl corrosion for damage rate determination) Required Data The basic component data required for analysis is given in Table and the specific data required for determination of the CLSCCClSCC DF is provided in Table Basic Assumptions The main assumption in determining the DF for CLSCCClSCC is that the damage can be characterized by a susceptibility parameter that is designated as high, medium, or low, or negligible based on process environment, material of construction, and component fabrication variables (e.g.i.e., heat treatmentwelding, cold forming). Based on the susceptibility parameter, a Severity Index is assigned that is a measure of the component susceptibility to cracking (or the probability of initiating cracks) and the probability that the crack will result in a leak.

7 If cracks are detected in the component during an inspection, the susceptibility is designated as High, and this will result in the maximum value for the Severity Index. Cracks that are found during an inspection should be evaluated using Fitness-For-Service methods in API 579-1/ASME FFS-1 [4] Determination of the Damage Factor Overview ClSCC A flow chart of the steps required to determine the DFf DF for CLSCCClSCC is shown in Figure The following sections provide additional information and the calculation procedure Inspection Effectiveness Inspections are ranked according to their expected effectiveness at detecting for CLSCCClSCC. Examples of inspection activities that are both intrusive (requires entry into the equipment) and nonintrusive (can be performed externally), are provided in Annex 2.C, Table 2.C.9.6. If multiple inspections of a lower effectiveness have been conducted during the designated time period, they can be equated to an equivalent higher effectiveness inspection in accordance with Section Calculation of the Damage Factor ClSCC The following procedure may be used to determine the DF DF for CLSCCClSCC, see Figure a) a) STEP 1 Determine the ssusceptibility for cracking using Table 12.2 and Figure 12.1 and Table Figure The Susceptibility for cracking is based mainly primarily on the operating temperature and and concentration of the chloride ions ph of the Cl-containing solution. (The Susceptibility is determined by adding the Environmental Susceptibility Modifier Values to the Base Likelihood determined by the ph and Operating Temperature.) Note that a HIGH susceptibility should be used if cracking is confirmed to be present. b) b) STEP 2 Based on the susceptibility in STEP 1, determine the severity index, SVI VI S, from Table c) c) STEP 3 Determine the time in-service, age age, since the last Level A, B or C inspection was performed with no cracking detected or cracking was repaired. Cracking detected but not repaired should be evaluated and future inspection recommendations based upon FFS evaluation. d) d) STEP 4 Determine the number of inspections, and the corresponding inspection effectiveness category using Section for past inspections performed during the in-service time. Combine the inspections to the highest effectiveness performed using Section ClSCC e) e) STEP 5 Determine the base ClSCC DF, DF fb for CLSCCClSCC, f) CLSCCClSCC g)e) fb D, using Table 6.3 based on the number of and the highest inspection effectiveness determined in STEP 4, and the severity index, S VI VI S, from STEP 2. ClSCC f) f) STEP 6 Calculate the escalation in the final DF, DF f, based on the time in-service since the last inspection using the age age from STEP 3 and Equation (2.2931). In this equation, it is assumed that the probability for cracking will increase with time since the last inspection as a result of increased exposure to upset conditions and other non-normal conditions. f

8 ClSCC f ClSCC ( ( [,1.0] ) 1.1,5000 fb ) D = Min D Max age (2.29) Nomenclature age is the component in-service time since the last cracking inspection or service start date ClSCC D f is the DF for ClSCC ClSCCC D fb is the base value of the DF for ClSCC S VI is the severity index Bibliography References 1. D. R. McIntyre and C. P. Dillon, Guideline for Preventing Stress Corrosion Cracking in the Chemical 1. Process Industries, Publication 15, Materials Technology Institute of the Chemical Process Industry, Stress Corrosion Cracking and Hydrogen Embrittlement of Iron Base Alloys, Edited by R. W. Staehle, et. al., 2. NACE-5, NACE International, Houston, TX, Corrosion in the Petrochemical Industry, Edited by Linda Garverick, Essential Research, pages , 3. ASM International, Materials Park, OH, API Standard API 579-1/ASME FFS-1 5. ASTM STP No. 264, Report on Stress-Corrosion Cracking of Austenitic Chromium-Nickel Stainless Steels (1960) 6. Rideout, P.S., Abstract 67, Corrosion Conference Scharfstein, L.R. & Brindley, W.F., Corrosion, 14, N12, Rion, W.C., Industrial & Engineering Chemistry, 49, 73A (March 1957)

9 12.8 Table Table 12.1 Data Required for Determination of the Damage Factor ClLSCC Required Data Susceptibility (None, Low, Medium, High) Cl - Concentration of Process Water (ppm) Operating Temperature, C ( F) Comments The susceptibility is determined by expert advice or using the procedures in this section. Determine the bulk Cl - concentration of the water phase. If unknown, the default value for ppm is > 1,000. Consider Cl - content of any water present in system (i.e., hydrotest, boiler feed, steam). Also, consider the possibility of concentration of Cl - by evaporation or upset conditions. Determine the highest operating temperature expected during operation (consider normal and non-normal operating conditions). ph of Process Water Age (years) Inspection Effectiveness Category Number of Inspections Temperature ( F) Determine ph of the process water. High ph solutions with high chlorides generally are not as susceptible to cracking as low ph solution with chlorides. Use inspection history to determine the time since the last SCC inspection. The effectiveness category that has been performed on the component. The number of inspections in each effectiveness category that have been performed. Table 12.2 Susceptibility to Cracking CLSCC ph 10 Susceptibility to Cracking as a Function of Chloride ion (ppm) ,000 > 1,000 <100 Low Low Low Medium > Low Medium Medium High > Medium Medium High High > Medium High High High >300 High High High High ph > 10 Temperature ( F) Susceptibility to Cracking as a Function of Chloride ion (ppm) ,000 > 1,000 <100 None None None None > Low Low Low Low > Low Low Low Medium > 300 Medium Medium Medium High

10 Table 12.2M Susceptibility to Cracking CLSCC Temperature ( C) ph 10 Susceptibility to Cracking as a Function of Chloride ion (ppm) ,000 > 1,000 < 38 Low Low Low Medium >38 66 Low Medium Medium High >66 93 Medium Medium High High > Medium High High High >149 High High High High Temperature ( C) ph > 10 Susceptibility to Cracking as a Function of Chloride ion (ppm) ,000 > 1,000 < 38 None None None None >38-93 Low Low Low Low Low Low Low Medium >149 Medium Medium Medium High

11 Temperature, ( F) Table 12.2 Susceptibility to ClSCC Susceptibility to Cracking as a Function of ph < > 11.0 < 30 None None None None None None None None None None None None None None None None None None None None None None None None None None None None None None None None None None None None None None None Low Low Low Low None None None None None None None None None None None None None None None Medium Medium Medium Low Low Low Low Low Low Low Low Low Low Low None None None None None High High Medium Medium Medium Medium Medium Medium Medium Medium Low Low Low Low Low None None None None High High High High High High High Medium Medium Medium Medium Low Low Low Low Low Low None None High High High High High High High High Medium Medium Medium Medium Medium Medium Medium Low Low None None High High High High High High High High High High High High High High High Low Low None None High High High High High High High High High High High High High High High Low Low None None High High High High High High High High High High High High High High High Low Low None None High High High High High High High High High High High High High High High Low Low None None High High High High High High High High High High High High High High High Low Low None None High High High High High High High High High High High High High High High Low Low None None High High High High High High High High High High High High High High High Low Low None None High High High High High High High High High High High High High High High Low Low None >345 None None None None None None None None None None None None None None None None None None None Notes: 1. Decrease one susceptibility category if chloride concentration is < 10 ppm 2. Decrease one susceptibility category if oxygen concentration is < 90 ppb 3. Increase one susceptibility category if chloride concentration is > 100 ppm 4. Increase one susceptibility category if deposits are present where chlorides may concentrate 5. No cracking susceptibility, go to HCl corrosion to determine corrosion rate

12 Temperature, ( C) Table 12.2M Susceptibility to ClSCC Susceptibility to Cracking as a Function of ph < > 11.0 < -1.1 None None None None None None None None None None None None None None None None None None None None None None None None None None None None None None None None None None None None None None None Low Low Low Low None None None None None None None None None None None None None None None Medium Medium Medium Low Low Low Low Low Low Low Low Low Low Low None None None None None High High Medium Medium Medium Medium Medium Medium Medium Medium Low Low Low Low Low None None None None High High High High High High High Medium Medium Medium Medium Low Low Low Low Low Low None None High High High High High High High High Medium Medium Medium Medium Medium Medium Medium Low Low None None High High High High High High High High High High High High High High High Low Low None None High High High High High High High High High High High High High High High Low Low None None High High High High High High High High High High High High High High High Low Low None None High High High High High High High High High High High High High High High Low Low None None High High High High High High High High High High High High High High High Low Low None None High High High High High High High High High High High High High High High Low Low None None High High High High High High High High High High High High High High High Low Low None None High High High High High High High High High High High High High High High Low Low None > None None None None None None None None None None None None None None None None None None None Notes: 1. Decrease one susceptibility category if chloride concentration is < 10 ppm 2. Decrease one susceptibility category if oxygen concentration is < 90 ppb 1.3. Increase one susceptibility category if chloride concentration is > 100 ppm 4. Increase one susceptibility category if deposits are present where chlorides may concentrate 5. No cracking susceptibility, go to HCl corrosion to determine corrosion rate Formatted: Superscript

13 Table 12.3 Determination of Severity Index ClLSCC Susceptibility Severity Index S VI High 5,000 Medium 500 Low 50 None 0

14 Figures Temperature, O C Solution ph Chart Key Base Likelihood of Cracking Susceptibility Value None 1 Low 2 Medium 3 High 4 Out of Scope N/A (go to HCl corrosion) Environmental Susceptibility Modifiers Modifier Variable -1 Cl <10 ppm -1 Oxygen < 90 ppb +1 Cl >100 ppm +1 Deposits Note: Final Cl SSC susceptibility is determined by adjusting susceptibility with the applicable environmental susceptibility modifiers using ph and operating temperature Temperature, O F Formatted Table Figure 12.1 Determination of ClSCC Susceptibility

15 STEP 1: Determine the Susceptibility Using Table 12.2 and Figure 9.1. Temperature Cl - Contact Cracks present? Yes High Susceptibility Cracks Removed? No STEP 2: Determine the severity index from Table Yes No FFS STEP 3: Determine the time in-service, age, since the last inspection. STEP 4: Determine the number of inspections and the corresponding inspection effectiveness category for all past inspections using Table 2.C.9.4. STEP 5: Determine the base damage factor for ClSCC using Table 6.3. STEP 6: Calculate the escalation in the damage factor using Equation (2.29). Figure Determination of the ClLSCC DF

16 Figure 12.2 Table 12.2 Figure 12.1

17 DEGREES CENTIGRADE Base Likelihood of ClSCC at Process ph and Operating Temperature (Has liquid H2O) SOLUTION ph Chart Key Base Likelihood No Cracking Likely Low Likelihood of Cracking Medium Likelihood of Cracking High Likelihood of Cracking Pitting, Corrosion Environmental Susceptibility Modifiers -1 Cl <10 ppm -1 Oxygen < 90 ppb +1 Cl >100 ppm -1 PWHT Likelihood Value N/A DEGREES FARENHITE Figure 12.2

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