AB-505 Risk Based Inspection Programs For Pressure Equipment
AB-505 Risk Based Inspection Programs For Pressure Equipment
AB-505 Risk Based Inspection Programs For Pressure Equipment
AB–505
Table of Contents
FOREWORD .................................................................................................................................... ii
1.0 INTRODUCTION ................................................................................................................... 1
2.0 DEFINITIONS........................................................................................................................ 3
3.0 GOVERNING LEGISLATION ................................................................................................ 5
4.0 REFERENCED PUBLICATIONS .......................................................................................... 6
5.0 GENERAL ............................................................................................................................. 7
6.0 REQUIREMENTS FOR AN AUTHORIZED RISK-BASED INSPECTION PROGRAM .......... 9
6.1 LOGICAL AND FULLY DOCUMENTED PROCESS .....................................................10
6.2 RBI TEAM / PERSONNEL.....................................................................................10
6.3 DOCUMENTATION ..............................................................................................12
6.4 PRE-COMMISSIONING INSPECTIONS ....................................................................12
6.5 MANAGEMENT OF CHANGE .................................................................................12
APPENDIX A: KEY ELEMENTS OF A RBI PROCEDURE ............................................................ 14
1. SYSTEM DEFINITION/DATA COLLECTION ..............................................................14
2. HAZARD/DEGRADATION MODE IDENTIFICATION ....................................................15
3. CONSEQUENCE ASSESSMENT ............................................................................15
4. PROBABILITY ASSESSMENT ................................................................................16
5. RISK DETERMINATION ........................................................................................18
6. MITIGATION/INSPECTION PLAN/STRATEGY ...........................................................18
7. RE-ASSESSMENT ...............................................................................................19
7.0 REVISION LOG .................................................................................................................. 20
FOREWORD
As provided for under Sections 11, 12 and 13 of the Pressure Equipment Safety
Regulation (PESR), the Administrator in the pressure equipment discipline has
established that ABSA document AB-505 “Risk Based Inspection Programs for
Pressure Equipment” specifies information required by the Administrator from an owner
that applies for risk-based inspection (RBI) to be included in their certificate of
authorization permit as required under Section 11(3); and specifies features of a quality
management system that may be acceptable to the Administrator, as provided for under
Sections 12 and 13 of the PESR.
1.0 INTRODUCTION
This edition of AB-505 has been revised to reflect current API, ASME and other
industry-recognized good engineering practices and to address improvements that were
identified in the application of the previous edition of AB-505.
RBI can be very beneficial (increased reliability and safety; better understanding of risk;
allows owner to better allocate resources; etc.). However, if not properly applied, the
RBI process can focus attention away from items that are incorrectly assessed as
having a low risk. This can result in hazardous situations.
An owner, who utilizes RBI to determine the type, frequency and degree of inspection of
pressure equipment and pressure relief valve servicing intervals, must hold a quality
management system certificate of authorization permit (CAP), per 11(3) of the PESR.
The CAP must have risk-based inspection listed in the authorized scope. Effective use
of RBI in this context requires formal management processes, detailed development
and planning, and involvement of an experienced multi-disciplinary team (see section
6.2 Personnel). It should be noted that RBI is a continually changing, dynamic process.
It is essential that the required resources are available to validate the RBI assessments
throughout the full lifecycle of the equipment. For those programs with RBI in the scope
of their CAP, the progressive grading system shown in AB-506 does not apply.
However, owners must be aware of the following limitations:
The maximum thorough RBI assessment interval is ten years;
The maximum thorough inspection interval for directly fired power and heating
boilers is four years;
The maximum pressure relief valve servicing interval is ten years.
ABSA documents, such as AB-505 and AB-506, were developed with the close
cooperation of owners and other stakeholders. Their input has been invaluable in
compiling this document. In particular, we would like to acknowledge the following user
groups that represent the industry sectors in Alberta:
Alberta Refinery & Petrochemical Inspection Association (ARPIA)
Upstream Chief Inspectors Association (UCIA)
Contract Chief Inspectors Association (CCIA)
Generation Utilities Advisory Committee (GUAC)
Integrity Management Association Pulp Producers (IMAPP)
ABSA policy documents are living documents that are reviewed periodically to ensure
that they are aligned with current industry practices. We would welcome any
suggestions you have to improve AB-505. Please provide your comments to:
Mike Prefumo
Manager of Inspections
prefumo@absa.ca
The American Petroleum Institute (API) Codes and The National Board of Boiler and
Pressure Vessel Inspectors (NB) publications are recognized and generally accepted as
good engineering practice. Relevant information from these documents and other
reference publications has therefore been considered in preparing AB-505 and other
ABSA documents.
The NB and API publications are not adopted by the PESR. The application of these
standards is established through their reference in applicable ABSA documents.
Owners are cautioned to ensure that current versions of the relevant good engineering
practices, that are applicable to their specific industry sectors, are used to supplement
the requirements covered in AB-505.
2.0 DEFINITIONS
For the purpose of AB-505, the following definitions apply. Relevant definitions, from the
Alberta Safety Codes Act and Pressure Equipment Safety Regulation, are also included
in this section.
In-service – the period of time during the life of pressure equipment from the beginning
of commissioning until disposal.
Integrity Operating Windows (IOW) – a set of limits used to determine the different
variables that could affect the integrity and reliability of a process unit or system.
Owner – includes a lessee, a person in charge, a person who has care and control, and
a person who holds out that the person has the powers and authority of ownership or
who for the time being exercises the powers and authority of ownership. [SCA, 1(1)(v)]
Public occupancy – is defined as any facility where members of the general public are
likely to be present. This would include schools, offices, shopping malls, stores, arenas,
pools, restaurants, hotels, etc.
Quality Manual – as used in this document, means a written description of the quality
management system. An owner, who has implemented, or will implement, a quality
management system, has the discretion to determine the format of the document. It is
not necessary for the written description of the quality management system to be
presented as a stand-alone “quality manual”.
Risk – the product of the probability of the failure of an item and the expected
consequences should that failure occur.
Note: The Pressure Equipment Safety Regulation User Guide (AB-516) provides valuable
information to assist stakeholders in meeting the requirements of the Pressure Equipment
Safety Regulation and in assuring the safe operation of their pressure equipment.
API RP 580/581 and ASME PCC-3 are widely used and recognized generally accepted
codes and standards governing risk-based inspection. Information from these
publications, and other relevant good engineering practices, has been used in
preparation of the AB-505.
The following referenced ABSA documents have been approved by the Administrator to
establish the requirements that must be met for in-service pressure equipment under
the PESR. The requirements documents shown below, and other ABSA requirements
documents and guidelines, are available on the www.absa.ca website.
Referenced Codes and Standards and other Recognized and Generally Accepted Good
Engineering Practices:
5.0 GENERAL
RBI may be applied in any industry in Alberta, provided the requirements of AB-505 and
AB-506 are met.
Pressure equipment, for process applications installed in Alberta, covers a broad range
of facilities from major petrochemical plants, pulp mills, and power utilities to small oil
and gas processing facilities, commercial facilities and other applications. The extent of
an owner-user’s integrity management system and the RBI processes needed to
achieve an effective and practical RBI program will therefore vary considerably and will
also depend on the equipment that is to be included in the RBI assessment, and
whether the risk-based inspection program is authorized under the PESR (refer to
section 6 of this document).
In general, the risk is determined in accordance with a defined, logical and consistent
method. The probability and consequences of failure are determined for each item
through a qualitative assessment or, in some cases, a more rigorous quantitative
The use of a RBI approach to manage pressure equipment safety offers many benefits.
Primarily, it allows inspection resources to be allocated in the most efficient manner to
minimize risk. A proper RBI assessment may show that a reduced frequency or scope
of inspection for lower risk items is justified. It allows a benefit analysis to be performed
whereby the owner can ensure that inspection resources are being allocated properly.
Traditionally, mitigation (such as inspection) is focused on reducing the probability of
failure. Since a RBI program causes the owner to consider consequences, other
mitigation methods, designed to reduce the consequences of failure, may identify
alternate techniques that should be applied to a particular vessel or system.
RBI is a complex process that requires careful and detailed development and planning.
It is not the intent of this document to provide comprehensive information regarding RBI
program development. Persons wishing to implement a formal risk-based inspection
program should refer to the referenced documents and to the various publications and
guidance information that is available, some of which is listed below:
The following establishes the requirements that must be met when RBI is used to
determine the appropriate thorough inspection intervals and the type and extent of
future inspections/examinations for pressure equipment, as well as the servicing
intervals for pressure relief devices. Owners who use this option must hold a CAP, per
11(3) of the PESR, which has risk-based inspection listed in its authorized scope.
The use of a less-than-fully-quantitative (i.e. not fully API 581, Section 7 compliant)
risk-based approach to determine the pressure relief valve (PRV) maximum servicing
intervals that do not exceed the AB-506 maximum servicing intervals is acceptable. This
approach should be described in the owner’s risk-based inspection procedures.
An owner, who wishes to exceed the AB-506 maximum servicing intervals for PRVs
through a risk-based inspection program, shall utilize API 581 (Section 7) as the
foundation of their risk-based program, where the servicing interval is commensurate
with the inherent risk of the relief device. The risk assessment shall be quantitative in
nature and shall consider the valve failing to open, as well as premature leakage. The
owner’s pressure relief device RBI program shall also include aspects of API 576 for
condition based inspection and monitoring, which contributes into the determination of
the risk.
The owner must have the required resources, structure and management processes to
ensure the RBI is appropriate. This would normally require that they have suitable
in-house resources and have operated under an owner-user CAP for at least three
years, and have had at least one satisfactory CAP renewal audit.
If a consultant is used to assist with RBI implementation the owner shall have a
documented assessment process in place, and shall be responsible for assuring that
the consultant is capable of providing integrated services and assisting in the
development of the RBI program. It is essential that the personnel involved in the
operation of the RBI program are intimately familiar with the processes, operating
parameters, procedures, history and other factors to make thorough risk assessments.
Furthermore, since risk tolerance is highly subjective, it is mandatory that senior
management has documented and approved policies and procedures governing RBI
and has defined acceptable risk tolerance.
RBI and inspection planning requires a range of technical input and perspectives
from different disciplines and therefore is best undertaken by a team. The
number of team members and the team composition will vary, depending on the
The team should have a team leader with the authority to manage the team and
the responsibility for ensuring that an appropriate RBI plan is developed. If a
company proposes to contract some, or all, of this work to an outside vendor,
then the process for controlling outside consultants must be defined. External
experts and consultants can contribute valuable technical knowledge and
experience, and also provide a useful degree of independence and objectivity in
assessing the risks and the adequacy of the proposed system. However, the
owner must have a suitable structure and organization to review and
evaluate/validate RBI results.
The RBI program must define the personnel who will participate during each
stage of the risk assessment, including their required qualifications, training, plant
specific knowledge and experience. Key RBI team members may include:
a team leader/facilitator
Chief Inspector
equipment inspectors
a corrosion specialist with sufficient qualifications and experience to
understand the process, predict failure mechanisms and identify
limitations in inspection techniques
process specialists
operations specialists
maintenance specialists
management
risk assessment personnel
environment and safety personnel
financial and business personnel
A knowledgeable person operating the RBI computer model
The role of the company chief inspector in the RBI process must be clearly
defined.
Part of the RBI process must include a documented process for assessing the
competency level of the personnel involved in the risk assessment to ensure the
team has the required knowledge and experience to make sound judgments. The
RBI team members shall have appropriate knowledge of the company’s RBI and
pressure equipment integrity management program, and of risk analysis. The
team leader must have sufficient all-round technical knowledge and experience
of the plant to know what information is required and where to find it.
All personnel participating in the RBI program must be fully trained in the
program and understand the implications of the decisions made. Their training
must be documented.
The impact of personnel changes on the RBI program must be managed and
controlled to ensure the continued competency of persons involved in the RBI
process.
6.3 Documentation
It is essential that all RBI assessments be clearly documented, with all factors
contributing to the final risk assessment being defined. At minimum, the
documentation must include:
team members performing the assessment and their qualifications,
re-assessment interval,
factors used to determine risk,
assumptions made during the assessment,
risk assessment results (unmitigated risk levels),
actions required to move to new mitigation risk levels,
mitigated risk levels, and
documented sign off and acceptance of the RBI assessment by the
responsible inspector.
A critical factor in the success of a RBI program is the ability of the company to
manage change. Even seemingly minor and insignificant changes can have a
tremendous impact on the probability or consequences of pressure equipment
failure.
Operating within the operating boundaries is critical to the validity of the risk
analysis, as well as good operating practice. Key process parameters (such as
IOWs) shall be monitored to determine whether operations are maintained within
the operating boundaries.
Any RBI program shall be linked to the management of change (MOC) process
the owner’s IMS is required to have as per the AB-512 requirements.
The process for evaluating the impact of changes must be addressed in the RBI
program and the documentation must be in sufficient detail to enable the impact
of a change to be fully understood.
The following discusses typical stages of a RBI assessment and defines the minimum
elements that must be addressed during each stage. The stages are as follows:
System Definition/Data Collection
Hazard/Degradation Mode Identification,
Consequence Assessment,
Probability Assessment,
Risk Determination,
Mitigation/Inspection Plan and
Reassessment.
As the exact process for assigning risk to pressure equipment will vary from company to
company, it is not necessary that the system outlined in this document be followed
exactly, provided that all essential elements are addressed. Much more detail regarding
risk assessment is available in some of the referenced documents, particularly
API RP 580.
This stage involves the collection of pertinent data to be used in assessing the
probability and consequence of failure for each pressure item. It identifies what
has been and what will be assessed, and what data will be collected.
Once the background information is in place, the hazards must be identified. This
involves identifying equipment specific potential and credible degradation modes
and damage mechanisms, using the inspection and process data and industry
experience. This stage is critical and requires careful analysis by a corrosion
specialist having sufficient detailed knowledge of the equipment, process, and
failure mechanisms to make accurate evaluations.
At this stage, potential failure scenarios (for example, pit to leak to ignition, or
crack to rupture) are to be identified based on the damage mechanisms
expected. This will assist in evaluating consequences and mitigation methods in
later stages.
3. Consequence Assessment
Although the other consequences are certainly important, they must not be given
higher importance than safety. As well, the importance of safety must not be
diluted due to the inclusion of other consequences in a RBI program.
4. Probability Assessment
In the context of RBI, probability is the likelihood that a given failure event will
occur. Probability is often measured as a frequency of failure events over a
period of time (for example - events per year). Probability assessment is often
considered the most difficult stage in determining risk. The owner must
demonstrate a valid process based on historical data, an understanding of failure
mechanisms, current operation, and recognition of possible future changes to
compile all available data into a single value or category.
5. Risk Determination
Based on the previously obtained consequence and probability of failure, the risk
level for each item can be assigned. The RBI program must define how risk is
derived. Typically, consequence and probability are plotted against each other in
a matrix with the location of the point falling into a range with a pre-defined risk
index. A generic example of a risk matrix is shown below in Figure 1. The same
matrix (or other method) must be used consistently for all risk assessments.
Increasing Risk
Probability of Failure
Increasing
Increasing
Consequence of Failure
Figure 1. Generic Risk Matrix
In most cases, the highest resulting risk for each item, based on the analysis,
should be used to determine the inspection and mitigation strategy. However, it
may be necessary to consider more than one risk level, if different degradation
modes that require different mitigation techniques are involved.
The critical step during this stage is the assignment of the level of risk to the
matrix. The RBI program must define how each risk will be addressed in terms of
inspection frequency, scope and other mitigation techniques. Typically, this is
achieved by segregating blocks in the matrix as having acceptable and
unacceptable risks, and assigning required actions for each risk level. This is a
policy decision that must come from upper management, within the owner
company, as defined in the owner-user program.
6. Mitigation/Inspection Plan/Strategy
7. Re-assessment
The RBI program must include updating the risk assessments to ensure that the
results are current with the most recent inspection, process, and maintenance
information. The effectiveness of mitigation techniques must be validated. At
minimum, the RBI re-assessments are to be performed under the following
conditions:
after changes to the process, the design or other critical factors, or when
new information becomes available that could impact the previous
assessment,
after new inspection data is obtained (after turnarounds),
after a preset maximum time period has elapsed.
The specified maximum time period must be established and documented with
respect to its suitability for ensuring that risk assessments remain current. Per
AB-506, the maximum time period cannot exceed ten years.