Regular inspections of in-service equipment and structures made of Fiber-Reinforced Polymer (FRP) composites give owner/operators important information about the condition and Fitness For Service (FFS) of their assets.
This information helps asset owners and reliability engineers maintain uninterrupted operations, ensure personnel safety, efficiently plan repairs and maintenance, and budget for capital expenditures.
History of FRP inspection guidance
Unlike steel, which has been used for industrial assets for more than a century, FRP materials first appeared in the 1950s.
In the years since then, more than 200 consensus codes and standards have been developed to provide guidance on the design and construction of FRP equipment.
However, a gap still remains in consensus guidance to assess FRP equipment once it is in operational service.
Today, due to a lack of FRP-specific consensus guidance for inspecting in-service equipment, asset owners largely rely on a patchwork of standards and codes originally created for steel equipment, or for new FRP construction, neither of which take into account the damage mechanisms that affect in-service FRP vessels, piping or other equipment and infrastructure.
Fortunately, this situation is changing with the first-ever consensus assessment standard for in-service FRP on the horizon (see more on API 579-1/ASME FFS-1, Part 16 below).
API and ASME standards and codes
The American Petroleum Institute (API) and American Society of Mechanical Engineers (ASME) are two key organizations that have developed detailed inspection codes for destructive and non-destructive testing (DT and NDT) of in-service pipes and vessels, including standards for ultrasonic inspection.
The API has developed more than 800 consensus standards over the last century, using a process accredited by the American National Standards Institute (ANSI).
ASME is the leading international developer of mechanical engineering codes and standards, with nearly 600 codes and standards currently available.
API 579-1/ASME FFS-1
At this time, the consensus codes developed by the API and ASME (API 579-1/ASME FFS-1) focus primarily on fitness for service assessments of metal pressure vessels and piping.
A new part (Part 16) to API 579-1/ASME FFS-1 is in development, which will include in-service FRP composite equipment for the first time.
Work on the new part is informed by Welding Research Council Bulletin 601, which provides reliability engineers with a technically valid, quantitative and repeatable process for evaluating in-service fiber-reinforced polymer (FRP) assets.
Consensus standards and ANSI principles
Consensus standards are developed through a process that ensures a fair, open, and inclusive approach, involving various stakeholders and adhering to specific principles.
The process of creating voluntary standards in the United States is guided by ANSI’s principles of consensus, due process, transparency and openness, and depends heavily on data-gathering and compromises among a diverse range of stakeholders.
ANSI ensures that access to the standards process, including an appeals mechanism, is made available to anyone directly or materially affected by a standard that is under development. Thousands of individuals, companies, government agencies, and other organizations such as labor, industrial, and consumer groups voluntarily contribute their knowledge, talents, and efforts to standards development.
Common inspection standards for in-service FRP equipment
Below are brief descriptions of inspection standards and codes that reliability engineers commonly use to identify flaws or defects in FRP (polymeric) composite equipment and structures.
Also see the interactive table for more details, including if an inspection standard or code is consensus-based. All consensus documents in the chart adhere to ANSI principles.
Note that the usefulness of these standards and codes varies for evaluating FRP, as some focus on steel equipment (again, FRP damage mechanisms are different) or they focus on new FRP construction (not on assets after they are in-service).
Gaps in applicability to in-service FRP composite assets are noted in the commentary below.
It’s also important to understand that while some of the following inspection processes provide SOME information about the state of an FRP asset (e.g., identify visible cracks, leaks or other defects), only two provide ALL the data required to determine if FRP equipment is Fit-For-Service and only one of them, UltraAnalytix NDE, provides the data required to determine Remaining Strength Factor of the FRP to align with the underlying principles of API 579-1/ASME FFS-1, which also allows calculation of the Remaining Life of the equipment.
ASTM E1067 can determine Fitness-For Service but does not provide sufficient data to determine Remaining Strength Factor nor any estimate of Remaining Life.
Usability of Common Inspection Standards for In-Service Polymeric Composite Equipment and Structures to determine Fitness For Service
National Board Inspection Code Part 2
HOIS Good Practice Guide on In-Service Inspection of Offshore Composite Components
Tank Inspection, Repair, Alteration, and Reconstruction
Pressure Vessel Inspection Code: In-service Inspection, Rating, Repair, and Alteration
Piping Inspection Code: In-service Inspection, Rating, Repair, and Alteration of Piping Systems.
Reinforced Thermoset Plastic Corrosion-Resistant Equipment
Fiber-Reinforced Plastic Pressure Vessels
Pressure Piping Code
Fiber-Reinforced Thermosetting-Resin Piping Systems
GRP tanks and vessels for use above ground
Standard Practice for Classifying Visual Defects in Glass-Reinforced Plastic Laminate Parts
Aboveground Storage Tank Inspection
In-service Inspection of Aboveground Atmospheric Fiberglass Reinfgorced Plastic Tanks and Vessels
Standard Practice for Acoustic Emission Examination of Fiberglass Reinforced Plastic Resin (FRP) Tanks/Vessels
UltraAnalytix inspection standard practices
Best practice for inspecting used fiber-reinforced plastics (FRP) equipment
*Observations or Measurements Required for Proposed Part 16 to API 579-1/ASME FFS-1
¹ A consensus document is defined as one which is governed by the Essential Requirements for Due Process. Learn more.
NBIC NB-23: National Board Inspection Code
This code follows the ANSI Essential Requirements for consensus.
This is a post-construction code that is intended to provide rules and guidance for post-construction activities, particularly inspection, of pressure retaining items. Part 2 is for In-service Inspection and Part 3 is for Repairs and Alterations.
Inspection of FRP pressure retaining components is not included in the main body, but is included in Supplement 4 of Part 2. All of the focus is on the visible appearance of the external and internal surfaces and no data is accumulated that allows determination of FFS as a structural property. The supplement is limited to use for vessels and tanks and does not include piping or ductwork.
- Inspector Qualifications for FRP are limited to inspectors or holders of “R” Stamp, associated with construction code activities, and are not formalized by a certification process.
- Requires internal inspection. One purpose is to determine the pressure integrity of the component. Items to look for are identified.
- Acceptance criteria are not provided. The implication is that acceptance criteria will be established by the inspector.
HOIS GP1: HOIS Good Practice Guide on In-Service Inspection of Offshore Composite Components
This is document focuses on inspection for compliance of in-service FRP piping with the original design specification. The primary means of inspection is ultrasonic and the focus is on overt defect detection. Note that this document treats FRP material the same way as steel instead of focusing on the actual damage that occurs to FRP materials.
API 653: Tank Inspection, Repair, Alteration, and Reconstruction
This is often considered to be the principal standard for storage tank inspection. However, the standard explicitly applies only to steel tanks. Not usable for FRP.
API 510: Pressure Vessel Inspection Code: In-service Inspection, Rating Repair and Alteration
This code only describes inspection practices for steel pressure vessels and pressure piping (not FRP).
API 570: Piping Inspection Code: In-service Inspection, Rating, Repair and Alteration of Piping Systems
This code includes FRP piping systems. In-service inspection of FRP piping is limited to inspection of the installation to identify installation defects and does not provide criteria to the inspector. No inspection instructions are provided after the piping goes into service. Note that piping construction codes include identical inspection requirements.
Construction Codes: RTP-1, B&PV.X, B31.1, B31.3, API 12P, NM.2, EN 13121
- Reinforced Thermoset Plastic Corrosion-Resistant Equipment (RTP-1)
- Fiber-Reinforced Plastic Pressure Vessels (B&PV.X)
- Pressure Piping Code (B31.1/B31.3)
- API SPEC 12P: Specification for Fiberglass Reinforced Plastic Tanks (API 12P)
- Fiber-Reinforced Thermosetting-Resin Piping Systems (NM.2)
- GRP tanks and vessels for use above ground (EN 13121)
None of these construction codes provide direction or specification for in-service inspection. All inspection and testing items listed in the construction codes apply to qualification of new equipment. Many codes explicitly state in their scope that they do not apply after equipment goes into service. One exception is EN 13121, which allows the tank manufacturer to identify or specify in-service maintenance and inspections.
FRPI-ASTCLM: Aboveground Storage Tank Inspection
This manual addresses 75% of the essential elements that would be required under the proposed new part (Part 16) for the API 579 Fitness for Service assessment. However, it does not include determination of the actual and expected operating pressures. The approach claims to be compliant with API 653 — which does not apply to FRP. Inspectors are expected to attend training, pass exams, have suitable experience and continue working as an inspector.
FT&V 2007: In-service Inspection of Aboveground Atmospheric Fiberglass Reinforced Plastic Tanks and Vessels
This manual provides some of the observations that would be required under the proposed new part (Part 16) for API 579 It claims to be compliant with API 653.
ASTM E1067: Standard Practice for Acoustic Emission Examination of Fiberglass Reinforced Plastic Resin (FRP) Tanks/Vessels
This provides the technical criteria for Acoustic Emission inspection, one of the methods included in the proposed new part for API 579.
UltraAnalytix® Non-Destructive Evaluation
UltraAnalytix NDE is based on several standard practices for where to obtain data, external inspection, based on other standards, including API 653 and 570. When used together, these provide all of the requirements for the proposed Part 16 update to API 579 assessment. All inspection processes included in the UltraAnalytix system are aimed at detection and evaluation of the condition of FRP using the primary damage mechanism of visco-elastic creep, whereas not a single one of the others except maybe AE addresses that.
TIP 0402-28: Best practice for inspecting used fiber-reinforced plastics (FRP) equipment
This document is focused on FRP equipment that is used in a very narrow process application and defines fitness for service based on visible criteria.
An Inspection Guide for Fiber-Reinforced Plastic (FRP) Equipment
This is a document produced by a resin manufacturer with the stated purpose of encouraging “informed and effective use of FRP”. It focuses on the same FFS criteria as TIP 0402-28.