Friday, December 30, 2011
Wednesday, December 21, 2011
Sunday, December 18, 2011
Level II certification courses at 'Trinity Institute of NDT' starts on 20th January 2012 in India
All the certification courses contains in depth theory, practical and examinations at the end of each course. The institute prepared syllabus to provide more emphasis on practical NDT and the trainers are with more than fifteen years of practical materials testing and nondestructive testing related experience and materials/metallurgical engineering background knowledge. The training center in India is equipped with modern class rooms with audio visual effects, workshops with latest ndt equipments, pleasant accommodation for outstation participants.
To know more about the detailed schedule, obtaining brochures email: training@trinityndt.com or call helpline at +91 9844129439/9900929439. Visit: www.trinityndt.com for latest brochure downloads.
Trinity NDT - Brief basics of Visual and Optical Testing(VT)
Visual Testing(VT) basic requirements
The tool that is used to perform VT is the human eye. The following are the requirements for the performance of VT:
Visual Acuity - Personnel who perform VT must pass an annual eye examination in accordance with industry standards. The eye examination checks for conditions such as visual acuity, color blindness, and depth perception.
Distance - The examiner’s eye should be located within 24 inches and at an angle of not less than 30 degrees to the surface of the weld that is being examined to conduct a direct visual examination. Mirrors can be used to improvethe angle of vision.
Access - If the area to be examined is not directly accessible, an examination aid can be used. Examinationaids are covered later in this Module.
Lighting - A flashlight or other additional lighting should be used to sufficiently illuminatethe area that is to be examined. A minimum of 35 foot candles of light should be available for normal visual weld examinations. When performing VT for small indications, a minimum of 50 foot candles of light should be available. If required by procedure, a light meter can be used to determine the exact amount of illumination that is available.
Examination Aids
Examination aids sometimes are used to facilitate visual examinations. The following are examples of commonly used visual examination aids:
1. Mirrors
2. Portable Lighting
3. Flashlights
4. Light Meters
5. Straight Edges and Rulers
6. Magnifying Lenses
7. Boroscopes
8. Microscopes
9. Video Cameras
10. Weld Gages
When the use of visual testing/examination aids (such as boroscopes) are necessary to perform remote examinations, the image resolution must be at least equal to the image resolution that is attainable by direct visual examination.
Several types of weld inspection gages are available to simplify the measurements of complex weld configurations when conducting VTs.
The following are some of the gauges that are generally used:
Cambridge Gage - This gage can measure undercut, weld reinforcement, bevel angle, root opening, fillet weld size, and joint mismatch.
GAL “Hi-Lo” Gage - This gage can measure joint mismatch, root opening, and weld reinforcement.
AWS Type Gage - This gage also can measure various sizes of standard fillet welds.
Common Applications
The following are common applications for visual weld examinations
- To determine the size and length of fillet welds on structural members
- To inspect the weld joint fit-up including bevel angle, root opening, land, and cleanliness of piping welds.
- To inspect in-process welds and completed welds prior to additional NDT.
- To inspect the proper fit-up of socket weld fittings on small diameter pipe.
The following are the common discontinuities that can be detected during a visual examination:
- Cracks
- Slag
- Porosity
- Undercut
- Cold Lap
- Arc Strikes
- Many more surface discontinuties
Purpose of Visual Inspection method The purpose of a visual weld examination (VT) is to detect visible surface discontinuities on a weldment. VT is the most frequently used method of examination, and welders and welding inspectors continuously use VT during welding operations to make better quality welds. VT often will identifyproblems during welding that can be repaired “in process” to prevent the discovery of a discontinuity by a subsequent nondestructive test.
Advantages of Visual Inspection method VT is the quickest and most cost-effective method of NDT for use in the identification of a surface discontinuity on a weld. Because the VT method of NDT requires the fewest technical and interpretive skills, VT also is the simplest NDT method to learn. The use of VT throughout the welding process significantly improves the success of subsequent NDT and reducesthe cost of repairs.
List of Important American Codes, Standards, Specifications related to NDT
American National Standards Institute (ANSI)
ANSI is the primary organization that is responsible for coordinating the activities of all other standard writing organizations. ANSI primarily reviews and certifies that the standards are correct. ANSI has established specific guidelines for the formation of other standard bodies such as ASME and AWS. Recently, several ANSI piping standards (B31.1, B31.3, B31.4 and B31.8) have been reclassified as ASME documents.
American Society of Mechanical Engineers (ASME)
ASME Codes are among the most widely used in the petrochemical industry and they govern items such as pressure vessels, boilers, and piping.
The following is a list of the ASME Codes
1. ASME Code B31.1
2. ASME Code B31.3
3. ASME Code B31.4
4. ASME Code B31.8
5. ASME Boiler and Pressure Vessel Code, Section I
6. ASME Boiler and Pressure Vessel Code, Section IV
7. ASME Boiler and Pressure Vessel Code, Section V
8. ASME Boiler and Pressure Vessel Code, Section VIII
ASME Code B31.1- Power Piping
Pertains to the design, materials, fabrication, test, and inspection of power and auxiliary piping. Typical systems include steam, water, gas, oil, and air services that support electric power generation.
ASME Code B31.3 - Chemical Plant and Petroleum Refinery Piping
Pertains to the design, materials, fabrication, test, and inspection of chemical piping systems. Typical applications include on-plot stripping steam, crude oil, acid, caustic, sour water, and cooling systems that are used to refine petroleum products.
ASME Code B31.4 - Liquid Transportation Systems for Hydrocarbons, Liquid Petroleum Gas, Anhydrous Ammonia, and Alcohols
Pertains to the design, construction, inspection, testing, operation, and maintenance of liquid petroleum and anhydrous ammonia piping systems. Typical applications include off-shore and off-plot cross-country pipelines, terminals, and tank farms.
ASME Code B31.8 - Gas Transmission and Distribution Piping Systems
Pertains to the design, fabrication, installation, inspection, testing, and operation of gas transmission and distribution systems (including gas pipelines), gas compressor stations, and gas metering and regulating stations.
ASME Boiler and Pressure Vessel Code, Section I - Power Boilers
Pertains to the design, material selection, fabrication, inspection, testing, and certification of power boilers that exceed 15 psi for steam service and that exceed 160 psi and/or 250oF for hot water service.
ASME Boiler and Pressure Vessel Code, Section IV - Heating Boilers
Pertains to the design, material selection, fabrication, inspection, testing, and certification of heating boilers that do not exceed 15 psi for steam service or that do not exceed 160 psi and 250oF for hot water service.
ASME Boiler and Pressure Vessel Code, Section V - Nondestructive Examination
Provides requirements and methods for NDT that include radiographic, ultrasonic, liquid penetrant, magnetic particle, eddy current, visual examination, leak testing, and acoustic emission.
ASME Boiler and Pressure Vessel Code, Section VIII - Pressure Vessels
Pertains to the design, material selection, fabrication, inspection, testing, and certification of pressure vessels. The three classes of pressure vessels that are covered by this code are welded, forged, and brazed. Typical applications include steam generators, heat exchangers, hydrocrackers, fractionation towers, reformer reactors, and other components that are designed to contain fluids or vapors at high temperatures and pressures.
American Society for Nondestructive Testing (ASNT)
ASNT is an organization that is dedicated to NDT. ASNT organizes and distributes technical information that is specific to NDT.
ASNT SNT-TC-1A - Recommended Practice for Personnel Qualification and Certification in Nondestructive Testing: Provides requirements for the qualification and certification of NDT personnel.
American Welding Society (AWS)
The AWS is an organization that provides standards for the welded fabrication of structures and bridges with structural steel and sheet metal.
AWS D1.1 - Structural Welding Code: Provides acceptance standards and welding requirements for buildings, bridges, and tubular structures. The requirements for the qualification of weld procedures and welders also are included in this Code.
American Petroleum Institute (API)
1. API 510
2. API 620
3. API 650
4. API RP-2A
API 510 - Pressure Vessel Inspection Code
Provides requirements for the maintenance inspection, repair, alteration, and relating procedures for pressure vessels that are used by the petroleum and chemical process industries.
API 620 - Design and Construction of Large, Welded, Low-Pressure Storage Tanks
Pertains to the design and construction of large, low pressure, above ground storage tanks. Typical applications include the storage of gases or vapors that results from refining operations.
API 650 - Welded Steel Tanks for Oil Storage
Provides material, design, fabrication, and testing requirements for above ground atmospheric tanks. Typical applications include the storage of crude and other liquid petroleum products.
API RP-2A - Recommended Practice for Planning, Designing, and Constructing Fixed Off- Shore Platforms:Provides a guide for the design and construction of drilling platforms.
Visit the following links to know more about international standards
All the above are registered trade/service marks of the respective institute/society. Consult the concerned Society/Institute stated above for buying the above codes, standards, specifications related to nondestructive testing-NDT
ASME www.asme.orgASNT www.asnt.orgASTM www.astm.orgAPI www.api.orgISO www.iso.chEN www.cen.eu All the above are registered trade/service marks of the respective institute/society. Consult the concerned Society/Institute stated above for buying the above codes, standards, specifications related to nondestructive testing-NDT
Subscribe to:
Posts (Atom)