SETSCO

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Inspection of Industry Equipment & Machinery

Tubing Inspection

Tubing inspection is recognized worldwide as an important factor in plant monitoring operation success. Effective monitoring and maintenance of a plant can result in fewer unscheduled stoppages, equipment failures, loses in production, unplanned expenditure on repair, injury and fatalities. Owners are increasingly aware of effective methods available for tube inspection and are adopting responsible, proactive approach towards predictive and preventive
maintenance.

Methodology:

Magnetic Flux Leakage Testing (MFLT)

This technique is based on the influence of defects on a magnetic field. The method is limited to ferromagnetic materials (carbon steel tubes). The MFL probe consists of a magnet with two types of magnetic pickups: coil type and hall element. The coil detects small defects that cause perturbations in the flux. The hall element sensor detects gradual wall loss. The output of the MFL coils is related to change of flux caused by the defect, but not the defect size. This technique therefore cannot be used to size flaws. In addition, rust at the ID surface will also produce noise type signals that can overshadow the defect signals.

Internal Rotary Inspection System (IRIS)

The IRIS (Internal Rotary Inspection System) uses a unique technique of displaying the pulse echo wall thickness image. Each rotation of the mirror produces a stationary, rectilinear image of the corresponding circumferential cross section of the tube wall. This image clearly differentiates between Internal and External defects and may be viewed (real time) on either the oscilloscope or the computer screen. Tubes require flooding for examination and effective cleaning ensures accurate test results.

Remote Field Eddy Current Testing (RFECT)

The Remote Field Eddy Current technique is used in the Inspection of Ferrous Tubes in Boilers, Exchangers, Condensers, Heaters, etc. in a large of industries worldwide. Tubes are tested in the dry condition with minimal influence from internal deposits, scanning included 360 around the tube circumference at scanning rates of 20 meters per minute.

Eddy Current Testing (ECT)

Conventional Eddy Current technique (ECT) is based on measuring the impedance of a coil. The impedance of the coil changes as the electromagnetic field interacts with the material. Initially, the coil is placed in the tube and balanced on the defect free material. The probe pulled, and variations in coil impedance recorded. The impedance changes are related to the type and size of a defect. Conventional eddy current inspection is fast and can be performed at speeds up to 6 feet per second. Conventional eddy current is limited to non-ferromagnetic materials. These include stainless steel, admiralty brass, copper-nickel alloys, titanium, hastelloy, etc.

Aboveground Storage Tank Testing & Inspection

Setsco also offers Aboveground Storage Tank Testing and Inspection services for the following programs: API 653 Inspections - Facilities may implement tank inspections in compliance with API 653 which includes a series of visual inspections and non-destructive examinations to assure continued tank integrity. Compliance with API 653 is achieved through the performance of specific inspections. Each type of inspection is summarized below.

Applications

  • Routine In-Service Inspections are monthly visual inspections conducted by owner/operator personnel who are knowledgeable of the facilities operations, the storage tank systems and the characteristics of the products stored. Personnel performing this inspection will be guided by a checklist developed by a qualified 653 inspector.

  • External Inspections are performed at least every five (5) years or at the quarter corrosion rate life of the shell, whichever is sooner. The inspections are performed by an API 653 Inspector guided by using an In-Service Inspection Checklist. At a minimum, the inspection consists of a comprehensive external visual inspection.

Methodology:

Ultrasonic Thickness Inspections of the shell are performed to determine a rate of uniform general corrosion and to provide indications of the integrity of the shell. Corrosion rates are determined in accordance with the latest edition of API 653. The maximum interval between inspections is five (5) years when the corrosion rate is not known and the maximum interval when the corrosion rate is known is the smaller of RCA/2N years (where RCA is the remaining corrosion allowance in mils and N is the shell corrosion rate in mils per year) or 15 years.

Internal Inspections are conducted at intervals determined by the corrosion rates measured during previous inspections. The bottom corrosion rates are controlled and the inspection interval is governed by the measured or anticipated corrosion rate and the calculations for minimum required thickness of the bottom given in API 653 Section 4.4.7. The actual inspection interval is set to ensure that the bottom plate minimum thickness at the next inspection is not less than the values listed in API 653. Internal inspection at a minimum consists of an ultrasonic thickness survey, magnetic flux leakage testing of bottom plates, comprehensive visual inspection, settlement survey, review of the routine inspection checklists, internal piping and auxiliary equipment inspection.