Committee Draft. Ballot ID: Tracking Status. Proposed Changes and/or Wording. Submitted to Task Group Submitted to SCI Submitted to Master Editor

Transcription

1 Ballot ID: Title: Purpose: Impact: Rationale: HIC/SOHIC Damage Factor Corrections: H2S, HF To improve the granularity of the damage factor calculations for H2S and HF HIC/SOHIC damage mechanisms. Will minimize recurring required inspections for very low susceptible applications Even for low susceptible applications, 581 will often require inspections every turn around. The goal is to minimize repeated inspections for very low susceptibility applications Technical Reference(s): API 571 Primary Sponsor: Name: Company: Phil Henry/ Mike Matrona Phone: (216) The Equity Engineering Group Tracking Status Submitted to Task Group Submitted to SCI Submitted to Master Editor Date Resolution Date Resolution Date Added Proposed Changes and/or Wording

2 Proposed Change to Table 6.3 Rationale: The changes being recommended to chapters 9 and 14 require a new row to be added to table 6.3 for an SVI of 0.5. S VI E Table 6.3 SCC Damage Factors All SCC Mechanisms Inspection Effectiveness 1 Inspection 2 Inspections 3 Inspections D C B A D C B A D C B A ,000 1, ,000 5,000 4,000 1, ,000 1, , S VI Inspection Effectiveness E 4 Inspections 5 Inspections 6 Inspections D C B A D C B A D C B A ,000 1, ,000 5,000 1,

3 Proposed change to Chapter 9 Rationale: Proposal is to add a VERY LOW susceptibility for HIC/SOHIC H2S cracking. We are also recommending the removal of the asterisks from the high category in table 9.2 because a very high category does not exist in the method. The goal is to minimize repeated inspections for very low susceptibility applications. For Table 9.2, the defined ph ranges were changed. API 571 states hydrogen diffusion through steel is minimal at ph 7, while noting the rate of diffusion increases at both higher and lower ph levels. The table was reconstructed in a manner that illustrated these claims. The <50 ppm column was separated into two columns: <5, and 5-50 ppm. API 571 provides the following justification: t f a r D An arbitrary value of 50 wppm H2S in the water phase is often used as the defining concentration where wet H2S damage becomes a problem. However, there are cases where cracking has occurred at lower concentrations or during upset conditions where wet H 2S was not ordinarily anticipated. The presence of as little as 1 wppm of H2S in the water has been found to be sufficient to cause hydrogen charging of the steel. This resolution increases the granularity of the method while providing more conservative values for H2S concentrations near 50 ppm. it e te Table 9.1 Data Required for Determination of the DF HIC/SOHIC-H2S Cracking Required Data Susceptibility (Very Low, Low, Medium, High) Presence of Water (Yes or No) o C m m H2S Content of Water ph of Water Presence of Cyanides (Yes or No) Sulfur Content of Plate Steel Comments The susceptibility is determined by expert advice or using the procedures in this paragraph. Determine whether free water is present in the component. Consider not only normal operating conditions, but also start-up, shutdown, process upsets, etc. Determine the H2S content of the water phase. If analytical results are not readily available, it can be estimated using the approach of Petrie & Moore (see Reference 31). Determine the ph of the water phase. If analytical results are not readily available, it should be estimated by a knowledgeable process engineer. Determine the presence of cyanide through sampling and/or field analysis. Consider primarily normal and upset operations but also start-up and shutdown conditions. Determine the sulfur content of the steel used to fabricate the component. This information should be available on MTRs in equipment files. If not available, it can be estimated from the ASTM or ASME specification of the steel listed on the U-1 form in consultation with materials engineer.

4 Steel Product Form (Plate or Pipe) Age (years) Inspection Effectiveness Category On-Line Monitoring (Hydrogen Probes, Process Variables, or Combination) Number of Inspections Determine what product form of steel was used to fabricate the component. Most components are fabricated from rolled and welded steel plates (e.g., A285, A515, A516), but some smalldiameter components are fabricated from steel pipe and piping components. Most small-diameter piping is fabricated from steel pipe (e.g., A106, A53, API 5L) and piping components (e.g., A105, A234), but most large diameter piping (above approximately NPS 16 diameter) is fabricated from rolled and welded plate steel. Use inspection history to determine the time since the last SCC inspection. The effectiveness category that has been performed on the component. The type of proactive corrosion monitoring methods or tools employed, such as hydrogen probes and/or process variable monitoring. The number of inspections in each effectiveness category that have been performed.

5 Table 9.2 Environmental Severity HIC/SOHIC-H 2 S Cracking ph of Water Environmental Severity as a Function of H2S content of Water < 50 ppm 5 to 50 ppm 50 to 1,000 ppm 1,000 to 10,000 ppm > 10,000 ppm < 45.5 Low Moderate Moderate High High 4 to 6.5 Very Low Low Low Moderate Moderate to 7.5 Low Very Low Very Low Low Low Moderate 7.6 to 8.3 Low Very Low Low Moderate Moderate* Moderate* 8.4 to 8.9 Low Very Low Low Moderate Moderate* High* > 9 Low Low Moderate High* High* Note: *If cyanides are present, increase the susceptibility to HIC/SOHIC-H2S one category for ph > and H2S concentrations greater than 1,000 ppm.

6 Table 9.3 Susceptibility to Cracking HIC/SOHIC-H 2 S Cracking Susceptibility to Cracking as a Function of Steel Sulfur Content Environmental Severity High-Sulfur Steel (1) > 0.01% S Low Sulfur Steel 0.01% Product Form Seamless/Extruded Pipe As-Welded PWHT As-Welded PWHT As-Welded PWHT High High High High Medium Medium Low Moderate High Medium Medium Low Low Low Very Low Low Medium Low Low Low Very Low Low Low Very Low Very Low Low Low Very Low Very Low Very Low Very Low Notes: 1. Typically includes A 70, A 201, A 212, A 285, A 515, and most A 516 before about Notes: Susceptibility Table 9.4 Determination of Severity Index HIC/SOHIC-H 2 S Cracking S Severity Index VI High 100 Medium 10 Low 1 Very Low 0.5 None A susceptibility level of none is indicative of the damage mechanism being inactive.

7 Proposed change to Chapter 14 Rationale: Proposal is to add a VERY LOW susceptibility for HIC/SOHIC HF cracking. The goal is to minimize repeated inspections for very low susceptibility applications. Table 14.1 Data Required for Determination of the DF HIC/SOHIC-HF Required Data Comments Susceptibility The susceptibility is determined by expert advice or using the (Very Low, Low, Medium, High) procedures in this paragraph. Presence of HF Determine whether HF may be present in the component. (Yes of No) Consider not only normal operating conditions but also upset conditions that may allow carryover of HF from other components. Sulfur Content of Plate Steel Determine the sulfur content of the plate steel used to fabricate the component. This information should be available on the material test report (MTR) in the equipment files. If not available, it can be estimated from the ASTM or ASME specification of the steel listed on the U-1 form in consultation with a materials engineer. Steel Product Form (Plate or Pipe) Age (years) Inspection Effectiveness Category Number of Inspections Determine what product form of steel was used to fabricate the component. Most components are fabricated from rolled and welded steel plates (e.g., A285, A515, A516), but some smalldiameter components are fabricated from steel pipe and piping components. Most small-diameter piping is fabricated from steel pipe (e.g., A106, A53, API 5L) and piping components (e.g., A105, A234), but most large-diameter piping (above approximately NPS 16 diameter) is fabricated from rolled and welded plate steel. 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

8 Table 14.2 Susceptibility to Cracking HIC/SOHIC-HF Susceptibility to Cracking as a Function of Steel Sulfur Content Weld High-Sulfur Steel Plate Construction Low-Sulfur Steel Product Form > 0.01% S 0.01% S Seamless/Extruded Pipe (2) Non-PWHT High High Low PWHT High Medium Low Notes: 1. Typically includes A 70, A 201, A 212, A 285, A 515, and most A 516 before about A Very Low susceptibility can be assigned to Seamless/Extruded Pipe under guidance of expert opinion. Notes: Susceptibility Table 14.3 Determination of Severity Index HIC/SOHIC-HF S Severity Index VI High 100 Medium 10 Low 1 Very Low 0.5 None A susceptibility level of none is indicative of the damage mechanism being inactive.