API RP 578
MODULE 5 : Part 2
API 570 EXAM STUDY GUIDE
API RP 578 : Guidelines for a Material Verification Program (MVP) for New and Existing Assets , 3rd Edition , February 2018
Continuation of API RP 578 [Module 5 : Part 1]
Considerations and General Concerns.
The MVP is to be implemented to avoid the consequences that may happen due to the substitution of unapproved material.
The code discusses 7 situations where there may have an unapproved substitution.
In that 4 situations are related to CS only.
1. Carbon steel substitution in Low-Alloy steel Material: Historically the greatest number of non-conformance's has occurred due to this. Physically these materials look very similar, so chances for mix-ups are more.
Example:
Instead of SA335 Gr P11, A 106 Gr.B is placed.
2. Alloy substitutions for CS: The reverse of the above condition also leads to failure and/or loss of containment in process streams which handles H2S, HF or H2SO4.
There is a
general thinking that higher grades can always be substituted in place of lower grade. Low-Alloy steel is
placed in CS lines. This will create great effect in process lines which
handles H2S, HF or H2SO4. We can see the requirement for PMI for CS lines in
some client specifications.
3. Residual Elements (RE) in CS in Hydrofluoric Acid Alkylation Units: IN HF fluid service increased corrosion rates can be experienced. PMI methods are adopted for this
4. Process Units Susceptible for Sulfidation: CS with Si<0.10% cab corrode faster than those with Si>0.10% when exposed to hydrogen-free sulfidation conditions.
The other three situations are as below
5. SS and Nonferrous Substitutions Within HIgh-alloy Systems: Mixup of Type 304 SS and Type 316 SS.Substitution of SS for Alloy 400 in HF alkylation services.
6. Gasket Materials: Gaskets in incompatible service may result in premature failures.
7. Refractory Installation Systems (Anchors): PMI testing is needed to verify that the refractory anchor match with the specifications (API 650).
A list of examples are given in Clause 5.2 of API 578.
Note: In this list bolting is also included though bolt is not exposed to process condition.
Rotating equipment pressure-containing components are to be included. Example for a pump; Impeller, Shaft, Casing and Mechanical seal.
More on this:
Flanges are included but PMI is not needed for Lap joint flange
Balancing line of valves are to be included in PMI
1. Several groups within the operating plant
2. Shop of a contractor
3. Distributor
4. Fabricator
Consideration should be given to the roles and responsibilities that each group has within the specific organisation. Roles and responsibilities should be clearly defined and documented. The owner/user or designee should specify the MVP requirements.
The owner/user should consider the following
1. Likelihood of unapproved material substitutions during previous projects and maintenance activities
2. Consequences of a failure due to improper material being installed
3. Reason for a specific material specification
4. Historical data relating to unapproved material substitutions.
Note: Reason for a specific material selection will be corrosion resistance or product purity.
Construction and Maintenance practices: PMI testing done at the time of construction and maintenance practices are to be considered
.
Reason for alloy specification: PMI is to be done if the alloy is used for corrosion resistance or structural integrity.
A MVP may not be necessary in some of the cases.
Example 1: SS lube oil systems in which SS is used foe maintaining oil purity
Example 2: SS in chemical manufacturing plant, where CS will cause product discoloration
Based on experience, some types of components can have higher likelihood of unapproved substitution, in such cases PMI is to be implemented.
PMI within the warehouse should NOT be regarded as an alternative to PMI of the fabricated assets when PMI is specified.
An immediate need may necessitate the installation of nonconforming materials in a temporary repair. Even very small changes has to be recorded and properly communicated.
Much of the PMI issues can be controlled through awareness of the issues at all levels within the repair process.
4. Process Units Susceptible for Sulfidation: CS with Si<0.10% cab corrode faster than those with Si>0.10% when exposed to hydrogen-free sulfidation conditions.
The other three situations are as below
5. SS and Nonferrous Substitutions Within HIgh-alloy Systems: Mixup of Type 304 SS and Type 316 SS.Substitution of SS for Alloy 400 in HF alkylation services.
6. Gasket Materials: Gaskets in incompatible service may result in premature failures.
7. Refractory Installation Systems (Anchors): PMI testing is needed to verify that the refractory anchor match with the specifications (API 650).
Material Verification Programs
Asset Components Included in a MVP
Pressure containing components exposed to process conditions to be included.A list of examples are given in Clause 5.2 of API 578.
Note: In this list bolting is also included though bolt is not exposed to process condition.
Rotating equipment pressure-containing components are to be included. Example for a pump; Impeller, Shaft, Casing and Mechanical seal.
Flanges are included but PMI is not needed for Lap joint flange
Balancing line of valves are to be included in PMI
Mill Test Reports (MTR) and Usage in a MVP
MTR is not a replacement to PMI. Historically these type of documents not always been accurate. MTR's are an important part of an overall material quality assurance program.Roles and Responsibilities
MVP involvement1. Several groups within the operating plant
2. Shop of a contractor
3. Distributor
4. Fabricator
Consideration should be given to the roles and responsibilities that each group has within the specific organisation. Roles and responsibilities should be clearly defined and documented. The owner/user or designee should specify the MVP requirements.
New construction MVP
The owner/user or designee should review and approve the MVP and the testing procedures, prior to testing.Prioritizing Assets for Retroactive PMI
General Factors to consider for implementation of MVP
The owner/user should establish a methodology for estimating the relative priority for PMI within a given unit. The methodology may be based on qualitative or quantitative risk analysis.The owner/user should consider the following
1. Likelihood of unapproved material substitutions during previous projects and maintenance activities
2. Consequences of a failure due to improper material being installed
3. Reason for a specific material specification
4. Historical data relating to unapproved material substitutions.
Note: Reason for a specific material selection will be corrosion resistance or product purity.
Site-Specific Factors to Consider for implementation of MVP
Site-Specific Factors and/or experience-based factors should be considered when prioritizing equipment or piping systems.Construction and Maintenance practices: PMI testing done at the time of construction and maintenance practices are to be considered
.
Reason for alloy specification: PMI is to be done if the alloy is used for corrosion resistance or structural integrity.
A MVP may not be necessary in some of the cases.
Example 1: SS lube oil systems in which SS is used foe maintaining oil purity
Example 2: SS in chemical manufacturing plant, where CS will cause product discoloration
Based on experience, some types of components can have higher likelihood of unapproved substitution, in such cases PMI is to be implemented.
MVP as an element of maintenance systems
Maintenance systems/ repair of assets also need a written procedure for the MVP. it is the responsibilty of Owner/user for the implementation of MVP for maintenance systems.PMI within the warehouse should NOT be regarded as an alternative to PMI of the fabricated assets when PMI is specified.
Maintenance Activities
An immediate need may necessitate the installation of nonconforming materials in a temporary repair. Even very small changes has to be recorded and properly communicated.
Much of the PMI issues can be controlled through awareness of the issues at all levels within the repair process.
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