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CHEMICAL PROCESS INDUSTRIESWelcome to IRISNDT'S QUALITY NONDESTRUCTIVE TESTING AND MATERIALS ENGINEERING SERVICES.
Offering services to the chemical process industries entails meeting their shutdown and every day emergency requirements. IRISNDT's commitment to customer service allows us to address these daily requirements. However, it also entails understanding that specialized chemical process equipment requires:
- Knowledge of the mechanical and corrosion damage mechanisms that impact equipment reliability.
- Using specialized tools and procedures to examine for these damage mechanisms.
- Having knowledgeable and committed personnel who know the history of the customers' equipment and their safety requirements.
- ASME PRESSURE VESSEL AND PIPING AS-BUILT INSPECTIONS
- MODULAR FABRICATION - INSPECTIONS
- DEVELOPMENT OF PIPING AND PRESSURE VESSEL RELIABILITY PROGRAMS
- ON-SITE MATERIALS ENGINEERING AND INSPECTION SERVICES
- HIGH TEMPERATURE HYDROGEN ATTACK ASSESSMENTS
- RISK BASED INSPECTIONS OF SPECIALIZED PRESSURIZED EQUIPMENT
- RUBBER SEALS, PLASTIC AND PLASTIC LINED EQUIPMENT FAILURE ANALYSES
- IN-SERVICE INSPECTIONS
- ADVANCED AND AUTOMATED UT
- TANK INSPECTIONS
ASME PRESSURE VESSEL AND PIPING AS-BUILT INSPECTIONS
The inspection of as-fabricated piping and pressure vessels has been at the core of our company's services since its creation in 1953. Then, the industry required us to perform radiography using isotopes and film. Today, while radiography continues to be the staple technology for as-fabricated vessels, we also inspect piping and pressure vessels using time of flight diffraction (ASME Code Case 2235). As well, we perform computed radiography which based on the ASME Code Case 2476 can be used in lieu of traditional radiography.
Inspecting nondestructively as-fabricated pressure vessels and piping built to meet ASME requirements requires skill, and an extensive quality assurance and safety program. In essence, the local pressure vessel safety authority must approve IRISNDT personnel as the fabricator's NDT Level III personnel. IRISNDT fulfills this role for over 50 fabrication shops within Alberta.
MODULAR FABRICATION - INSPECTIONS
Many of our more recent plant construction projects have required inspection of modules. This construction maximizes the inspection required at modular fabrication yards and minimizes the field welding and field radiography required during installation. In the field, our services must be available at all times to insure that critical examinations such as those of root passes and tie-ins are timely. Material verification tests are also critical in modular fabrication.
DEVELOPMENT OF PIPING AND PRESSURE VESSEL RELIABILITY PROGRAMS
Inspecting as-fabricated equipment has clearly established examination and testing requirements (for example those specified in ASME Section VIII, Division 1 and ASME Section V). However, inspecting equipment that has been in service requires detailed knowledge of the operation, potential damage mechanisms and the impact of equipment malfunctions on production. IRISNDT inspection and engineering personnel work jointly with our customers to tailor inspections to the corrosion and mechanical damage mechanisms of pressurized equipment. These services have been integral in the following projects:
- Replacement of 120" ID pressure vessel heads. The engineering support comprised details such as examinations to ensure that the older steel shell was weldable to a head made with a newer steel specification. A field temper bead welding procedure was developed to minimize heat damage to a vessel lead lining. Finally, to assess the quality of the welds an inspection program was developed encompassing:
- In conjunction with the pressure vessel owner/user of a high temperature water reactor, the following analyses/examinations were performed:
- Optimization of the ultrasonic identification and sizing of stress corrosion cracks at ambient and at high temperature. The sizing and reporting were optimized so that the results could be readily interpreted in the fitness for service model developed for the cracks. The shear wave crack length and depth assessments were correlated to metallographic measurements.
- Discussion on materials to be considered for building a high temperature water reactor. The discussion entailed searching the data published for the last 25 years by the nuclear industry. Fully post weld heat-treated low alloy steels and nickel alloys were considered. The discussion on materials included information on deposited weld metal as well as plate.
- Failure analysis of high temperature water pressure vessel low alloy steel. The investigation comprised the evaluation of failures of low alloy steels used in the nuclear industry for the last 25 years.
- Data evaluation of high temperature water electrochemical tests of nickel and low alloy steels.
- In conjunction with the owner/user of several liquid natural gas storage spheres, we developed a detailed inspection procedure for the equipment. The inspections were performed in lieu of the vessel being inspected internally. The program entailed:
ON-SITE MATERIALS ENGINEERING AND INSPECTION SERVICES
IRISNDT engineering personnel assist directly at plant sites for failure analyses, equipment repair and inspection projects. These services are especially useful during the commissioning and first 3 years of service of chemical plants. Many of our inspectors have participated for years as contractors for the inspection groups in various chemical processing plants.
HIGH TEMPERATURE HYDROGEN ATTACK ASSESSMENTS
After 20 years or more of service, piping and vessels containing hydrogen gas and operating at temperatures greater than 450 °F have developed high temperature hydrogen attack (HTHA). The attack can result in decarburization that weakens the steel and also in fine, discontinuous intergranular cracks.
The HTHA parent material surfaces can develop blisters and become decarburized; these types of damage can be noted visually and with replication. However, heat affected zone cracks may pass undetected even when performing wet fluorescent magnetic particle inspections of the process side. To identify these cracks, petrochemical and nondestructive testing companies have developed a series of ultrasonic examination techniques. Advanced Ultrasonic Backscatter Techniques (AUBT) using the Backscatter, Spectrum Analysis and the Velocity Ratio techniques are the more commonly known inspection methods. MATRIX (a subsidiary of IRISNDT) personnel perform AUBT inspections regularly for the petrochemical industry. See Power Point for more details.
RISK BASED INSPECTIONS OF SPECIALIZED PRESSURIZED EQUIPMENT
IRISNDT engineering personnel have developed risk based inspection (RBI) plans for pressurized equipment in cooperation with our customers. Based on these, inspections have been deferred to optimize the shutdown time, inspection time and practices and also the refurbishing plans for the equipment. For RBI, we take advantage of our knowledge of damage mechanisms and inspections while relying on the operating experience of our customers.
RUBBER SEALS, PLASTIC AND PLASTIC LINED EQUIPMENT FAILURE ANALYSES
Elastomer (rubber) seals improve our equipment and technology reliability daily. They prevent leakage of fuel into hot engine compartments in cars, airplanes and transport engines in general. They allow our air conditioning and heating glycol systems to function without leaks. They isolate contaminants so as to minimize industrial water and soil contamination.
In contrast to metal parts, elastomers can have an initial low cost. However, when seals fail, they can cause significant loss of production and secondary repair/replacement costs. At IRISNDT, our engineering group has examined the failures, developed testing programs and evaluated elastomers for challenging applications such as sealing steam, and solvent containing petrochemical fluids. We can assist you in the failure analysis and selection of gaskets and o-rings. See elastomer failure analyses PPT file.
Plastic and plastic lined equipment is much more than a cheap replacement for metal parts. Plastic (TeflonŽ PTFE and/or thermoplastic) lined steel pipe can transport hydrochloric acid for many years with minimal corrosion and/or structural damage. Instead, for the same low pressure and low temperature fluids, steel piping can have extensive losses. Nevertheless, plastics and plastic lined steel fail. At IRISNDT we have examined the failures of numerous process equipment components. We can assist you in optimizing the reliability of plastic components. See plastics failure analyses PPT file.
IN-SERVICE INSPECTIONS
- Crack Growth Monitoring for Fitness for Service Applications
If a vessel is cracked, repairing the flaws or replacing the cracked component is the most direct method for preventing leaking and/or a catastrophic failure. However, repairs/replacements are not always viable since:
- Some vessels may require a post weld heat treatment that cannot be performed in the field.
- Some vessels may require the removal of linings (coatings, bricks, insulation and others) or internal parts that cannot be replaced.
- Some vessels may require access to areas that are inaccessible due to surrounding components/parts.
- Some repairs can result in residual stresses that make the equipment more susceptible to cracking.
- Specialized vessels often require 2 or more years of fabrication.
- Some vessels may not be shutdown easily on short notice.
In these instances, monitoring cracks so that they do not leak or reach critical sizes may give an industrial plant the time to organize a suitable repair/replacement. IRISNDT personnel have ample experience in:
- Periodically sizing pressure vessel cracks with ultrasound both at high and at ambient temperature. The crack sizes are then compared with the crack sizes allowed in the Fitness for Service model to ensure that the cracks have not reached a critical size.
- Assessing the crack growth in coke drums, hydrocracking and other Heavy Walled Reactors with acoustic emission and ultrasound (see Matrix Website).
- Continuous On-Line Acoustic Emission Monitoring (see Matrix Website).
- Acoustic Emission Inspection of Seam Welded Hot Reheat Pipe
- CORROSION MAPPING
Knowing the profile of corroded areas allows the owner/user to periodically check the metal loss progress and determine when repairs are essential. IRISNDT ultrasonic inspection personnel perform both ambient and High Temperature Corrosion Mapping. These high resolution maps of corroded areas facilitate fitness for service evaluations.
High Temperature Corrosion Mapping, measurements at temperatures greater than 130 °F, is challenging:
- Special high temperature transducers are usually needed.
- Critical equipment with large suspect areas requires the entire area map to be compared periodically. However, the temperature of the transducer changes every time that it is lifted from the scanned surface. As the temperature changes, so do the electrical signals that are translated to a thickness value.
- Special couplants are required to insure that ultrasound is transferred effectively between the examined surface and the transducer.
All of this adds to the challenge. In response, Matrix Inspection & Engineering (a subsidiary of IRISNDT) has developed unique scanning systems that allow for longer transducer residence time and more reproducible data.
- PRESSURE VESSEL CLADDING INSPECTIONS
Roll or explosion-bonded cladded vessels are used to decrease the overall fabrication cost of vessels; they allow one to make a vessel with a carbon steel shell and a chemical or erosion resistant inside surface. On the other hand, inspecting the cladding from the carbon steel side is challenging. IRISNDT inspection personnel have performed critical and successful cladding inspections exemplified in Pressure Vessel Cladding Inspections.
- ACOUSTIC EMISSION OF IN-SERVICE PRESSURE VESSELS AND TANKS
Acoustic emission can be used to perform an overall structural integrity inspection for specific pressure vessels and tanks. Tanks and vessels that have a benign service can be tested with acoustic emission during an over-pressurization. Suspect areas, if found, can be further evaluated and sized with ultrasound (capturing computerized images). Based on a fitness for service evaluation:
- If suspect areas are found, they can be categorized as to whether they require immediate repairs or not. If immediate repairs are not required, the vessel/tank can remain in-service without having to be shutdown, emptied, cleaned for inspection and then refurbished for service.
- If significant flaws are found, the time for opening the tank/vessel can likely be deferred allowing planning time. For more information visit Matrix Website.
- PRESSURE SWING ABSORBERS
Pressure Swing Adsorbers are subject to fatigue cracking and require careful inspection. Internal inspection requires removal of catalyst and a lengthy shutdown. IRISNDT offers a number of external inspection options:
- Acoustic emission (AE) testing for on-stream crack detection.
- In service AE testing using a controlled off-line pressurization. This approach is useful for identifying problem areas just prior to a planned outage.
- Automated ultrasonic scanning of welds for crack detection on or off line.
- Measurements of weld peaking and other nozzle examinations as needed.
- PRESSURE VESSEL API 510, TANK API 653, AND PIPING API 570 IN-SERVICE INSPECTIONS
Vessels, tanks and piping require in-service periodic visual and corrosion monitoring. At IRISNDT, we have inspectors certified to all of these industrial standards who perform these periodic inspections.
- TANK BOTTOM INSPECTIONS
The tank (floor) condition can be assessed qualitatively with acoustic emission while in service:
- More AE indicates more damage.
- Experimental work shows scale build-up is a significant factor during the tank AE tests.
- AE activity is generated from corrosion processes, scale fracture and leaks.
For more details see Tank Bottom Testing.
ADVANCED AND AUTOMATED UT
We have a strong AUT group that performs these field inspections for many IRISNDT customers. The techniques performed include TOFD, phased array, and crack sizing. Typical applications are:
- Identifying lack of sidewall fusion in heavy wall pressure containing equipment welds.
- Inspecting heavy wall vessels for weld flaws following the ASME Boiler and Pressure Vessel Code Case 2235.
- Reproducible mapping and monitoring of corrosion metal general losses.
- Identifying and mapping Hydrogen Induced Cracking.
- Identifying and mapping High Temperature Hydrogen Attack.
- High temperature weld inspection for detection and monitoring of cracking
- High Temperature Corrosion Mapping.
- Rapid in service inspection of welds for service related damage.
- Pressure Vessel Cladding Inspections.
TANK INSPECTIONS
Since API 653 was introduced, operating companies have adopted a more comprehensive approach to the inspection of their storage tanks. The API 653 document describes the minimum requirement for the maintenance of storage tanks. Traditionally, all of this inspection was performed using manual techniques. However, the availability of new technology to scan large tank surfaces is altering the inspection methodology.
- Tank Floor Inspection
Before the 1990's, tank floors were inspected by cutting coupons from the floor to establish a baseline for the soil side condition of the floor. Since the introduction of a magnetic floor scanner, during 1989, the floor integrity no longer needs to be destroyed by removing coupons. Today, IRISNDT uses various magnetic flux exclusion (MFE) floor scanning tools.
These innovative MFE tools allow us to screen tank floors at rates as high as one thousand square feet per hour for soil side corrosion. The MFE tool detects corrosion whether it is located on the process or the soil side of the tank floor. Since the data is qualitative we perform additional inspections to quantify the corrosion depth. This is quantified using a mechanical pit gauge for top side corrosion, and ultrasonic inspections to assess soil side losses.
For further information, please view the following brochures:
