Ballot ID:
Title: HIC/SOHIC Damage Factor Corrections: H2S, HF
Purpose: To improve the granularity of the damage factor calculations for H2S and HF HIC/SOHIC damage mechanisms.
Impact: Will minimize recurring required inspections for very low susceptible applications
Rationale: 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: Phil Henry/ Mike Matrona
Company: The Equity Engineering Group
Phone: (216)283-6012
E-mail: [email protected]
Tracking Status
Submitted to Task Group Submitted to SCI Submitted to Master Editor
Date Resolution Date Resolution Date Added
Proposed Changes and/or Wording
Committee Draft
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.
Table 6.3 – SCC Damage Factors – All SCC Mechanisms
VIS
Inspection Effectiveness
E 1 Inspection 2 Inspections 3 Inspections
D C B A D C B A D C B A
0 0 0 0 0 0 0 0 0 0 0 0 0 0
0.5 0.5 0.5 0.3 0.2 0.13 0.3 0.2 0.15 0.1 0.2 0.13 0.1 0.05
1 1 1 0.7 0.5 0.3 0.7 0.5 0.3 0.2 0.5 0.3 0.2 0.1
10 10 8 3 1 0.5 6 2 0.5 0.3 4 1 0.5 0.2
50 50 40 17 5 3 30 10 2 0.5 20 5 1 0.3
100 100 80 33 10 5 60 20 4 1 40 10 2 0.5
500 500 400 170 50 25 300 100 20 5 200 50 8 1
1,000 1,000 800 330 100 50 600 200 40 10 400 100 16 2
5,000 5,000 4,000 1,670 500 250 3,000 1,000 250 50 2,000 500 80 10
VIS
Inspection Effectiveness
E 4 Inspections 5 Inspections 6 Inspections
D C B A D C B A D C B A
0 0 0 0 0 0 0 0 0 0 0 0 0 0
0.5 0.5 0.18 0.1 0.05 0.005 0.15 0.05 0.005 0.005 0.05 0.005 0.005 0.005
1 1 0.4 0.2 0.1 0.01 0.3 0.1 0.01 0.01 0.1 0.01 0.01 0.01
10 10 2 1 0.3 0.1 1 0.5 0.1 0.01 0.5 0.1 0.01 0.01
50 50 10 2 0.7 0.2 5 1 0.5 0.1 1 .5 0.1 0.01
100 100 20 5 1 0.3 10 2 0.7 0.2 5 1 0.3 0.1
500 500 100 25 2 0.7 50 10 1 0.5 25 5 0.5 0.3
1,000 1,000 200 50 5 1 100 25 2 0.7 50 10 1 0.5
5,000 5,000 1,000 250 25 2 500 125 5 1 250 50 2 1
Committee Draft
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:
“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 H2S 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.
Table 9.1 – Data Required for Determination of the DF – HIC/SOHIC-H2S Cracking
Required Data Comments
Susceptibility
(Very Low, Low, Medium, High)
The susceptibility is determined by expert advice or using the
procedures in this paragraph.
Presence of Water
(Yes or No)
Determine whether free water is present in the component.
Consider not only normal operating conditions, but also start-up,
shutdown, process upsets, etc.
H2S Content of Water 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).
pH of Water Determine the pH of the water phase. If analytical results are not
readily available, it should be estimated by a knowledgeable
process engineer.
Presence of Cyanides
(Yes or No)
Determine the presence of cyanide through sampling and/or field
analysis. Consider primarily normal and upset operations but also
start-up and shutdown conditions.
Sulfur Content of Plate Steel 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.
Committee Draft
Steel Product Form
(Plate or Pipe)
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 small-
diameter 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.
Age
(years)
Use inspection history to determine the time since the last SCC
inspection.
Inspection Effectiveness Category The effectiveness category that has been performed on the
component.
On-Line Monitoring
(Hydrogen Probes, Process
Variables, or Combination)
The type of proactive corrosion monitoring methods or tools
employed, such as hydrogen probes and/or process variable
monitoring.
Number of Inspections The number of inspections in each effectiveness category that have
been performed.
Committee Draft
Table 9.2 – Environmental Severity – HIC/SOHIC-H2S 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
5.5 6.6 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 > 7.6 8.3 and H2S concentrations greater than 1,000 ppm.
Committee Draft
Table 9.3 – Susceptibility to Cracking – HIC/SOHIC-H2S Cracking
Table 9.4 – Determination of Severity Index – HIC/SOHIC-H2S Cracking
Susceptibility Severity Index – VIS
High 100
Medium 10
Low 1
Very Low 0.5
None1 0 Notes:
1. A susceptibility level of “none” is indicative of the damage mechanism being inactive.
Environmental Severity
Susceptibility to Cracking as a Function of Steel Sulfur Content 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 1990.
Committee Draft
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
(Very Low, Low, Medium, High)
The susceptibility is determined by expert advice or using the
procedures in this paragraph.
Presence of HF
(Yes of No)
Determine whether HF may be present in the component.
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)
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 small-
diameter 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.
Age
(years)
Use inspection history to determine the time since the last SCC
inspection.
Inspection Effectiveness Category The effectiveness category that has been performed on the
component
Number of Inspections The number of inspections in each effectiveness category that have
been performed
Committee Draft
Table 14.2 – Susceptibility to Cracking – HIC/SOHIC-HF
Table 14.3 – Determination of Severity Index – HIC/SOHIC-HF
Susceptibility Severity Index – VIS
High 100
Medium 10
Low 1
Very Low 0.5
None1 0 Notes:
1. A susceptibility level of “none” is indicative of the damage mechanism being inactive.
Weld Construction
Susceptibility to Cracking as a Function of Steel Sulfur Content
High-Sulfur Steel Plate(1) > 0.01% S
Low-Sulfur Steel ≤ 0.01% S
Product Form – 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 1990.
1.2. A Very Low susceptibility can be assigned to Seamless/Extruded Pipe under guidance of expert opinion.
Committee Draft