The followings are the important vocabulary for API 570 course explained in simple language.
It not only helps you understand a few basic concepts, but some of these key words and their meaning may also be treated as potential exam questions.
Please note that the list in not exhaustive but it intends to explain important key words, their concepts and differences.
In case of conflict between reference documents such as code, recommended practice, standard, project specification, procedure, purchase order, etc., there shall be an order of precedence when one document over rules or vetoes another reference document.
For example, although API 570 code is the governing document that overrides even ASME B31.3 (Piping Construction code) when pipe is in service; API 570 cannot be in conflict with any prevailing regulatory requirement or jurisdictional regulation or government regulation unless it is more stringent than them.
Obviously, if API 570 is more stringent or more onerous than a regulation, this means, it is not in conflict with a regulation but is over and above that regulation.
It is not inspection which means verification.
The closest analogy could be the difference between a laboratory blood test (examination) and doctor’s diagnosis (which includes interpretation and prescription).
NDT technician examines (evaluates) the material by one of the NDT methods and reports the result (size, type and location of discontinuity).
NDT examiner can also report the acceptance or rejection of a material or equipment against an approved acceptance criteria if authorized by the inspector.
Please remember that the inspector is the final authority in accepting or rejecting the QC and NDT examination report.
is the visual inspection from outside the tank (maximum interval 5 years).
Imperfection and discontinuity are used interchangeably.
If it is unacceptable; that is, the size of discontinuity is beyond the acceptance criteria, then it is called a defect and is therefore rejectable; otherwise, the discontinuity is acceptable.
You have to compare the discontinuity against the acceptance and decide whether it is acceptable (termed discontinuity) or unacceptable (known as defect).
Evaluation is intended to identify the type, size and location of a discontinuity and categorizing it such as porosity, crack, lack of fusion, gas hole, stringer, and seam.
Interpretation means comparing the discontinuity against an approved acceptance criteria in order to determine whether it is acceptable or not.
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Precision and accuracy are often used interchangeably, but they have very different meanings.
Measurements that are close to the known value are said to be accurate (Calibrated), whereas measurements that are close to each other are said to be precise.
Accuracy is used for calibration purpose to determine how accurate the readings are with respect to a known value.
Precision shows variations. How close are a bunch of thickness measurement readings at a point on the vessel?
There are several key players that whose roles and responsibilities are described here:
API does not differentiate between owner and user.
This makes sense because if owner and user were differentiated as two separate legal entities, then, none of them could be hold them accountable because the owner would say that the user was supposed to comply with jurisdictional requirements while the user would argue that that the pressure vessel belongs to owner, and they should be held accountable.
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Inspector means authorized API 570 Piping Inspector.
The NDT examiner is responsible to carry NDT activities as per approved procedure and if authorized by the inspector, can also prepare the acceptance and rejection part of the report, however, please note that the Inspector is the final authority in accepting or rejecting the NDT reports as well as all the inspection records.
The piping engineer is an individual or a team who is knowledgeable in the design, review, analysis and evaluation of piping and is accepted by the owner/user.
An individual knowledgeable in materials, metallurgy, damage mechanism and corrosion monitoring techniques and is approved by the owner.
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This is the operating range such as the pressure and temperature range that the piping is allowed to work.
The range is determined by design and depends on the type of material and its thickness.
Exceeding the IOW range may affect the integrity of the piping.
Any change in the process piping or material or hardware shall be documented.
It shall be determined whether such changes may affect vessel integrity by increase in corrosion rate or change in damage mechanism.
Relevant personnel such as the Engineer, corrosion specialist, inspector, examiner and maintenance personnel may be involved to cascade such changes to inspection planning, repair and maintenance.
Points or areas are identified on the piping that normally expect to have the highest corrosion rate or stress concentration.
These areas are inspected and examined periodically to assess the piping condition.
CML are marked in order to measure thickness at the same points and compare it with previous readings as reference point.
The CML locations selected; should be representative of corrosion behavior of the piping.
The inspector selects the monitoring locations based on previous history of inspection, damages occurred on similar piping under similar operating and environmental conditions and may seek corrosion specialist opinion on expected damage mechanisms for a particular piping circuit.
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Quality assurance is the design and planning of quality control activities to ensure that the service or piping has met certain requirements
while the Quality Control is the implementation of those control activities in order to demonstrate or verify that those requirements are met.
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Remember that the owner/user is ultimately responsible for preparing, documenting, executing, and assessing piping/pressure-relieving device inspection and repair.
Owner/User shall have QA system that shall include:
As you can see, this is more or less, a list of ISO 9001 requirements.
Hardness is the resistance of material against penetration or indentation.
Toughness is the resistance of the material to deform under force/stress.
It is the area under the stress strain curve quantitatively.
Toughness depends both on amount of stress it can tolerate, and it’s amount of elongation.
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