Jumat, 18 Februari 2011

Test Services in O&G Sector

Mechanical Testing

instronMechanical testing or engineering test is performed to determine various mechanical properties of materials such as strength, hardness, ductility, toughness, brittleness, etc. There are several types of test to determine various mechanical and physical properties of material. The precision results of these tests is utilised to determine suitability of materials for the field application.


A. Tensile Testing
Tensile test is the most elementary type of mechanical test performed on materials. Tensile tests are simple, economical and traceable to the national standards. A tensile test also known as tension test is performed by holding the test items or test specimens in a suitable equipment. An axial pulling force is applied on the test item or test specimen and its behaviour under force is recorded on a conventional graph or chart or computerised data acquisition method.

tensile-testGenerally this test is performed at ambient temperature. Where a material is subjected to elevated temperature such as boilers and pressure vessel applications, a high temperature tensile test is performed. In Australia, AS 2291 specifies test method requirements for high temperature tensile test.

This test provides information such as Proof load, 0.2% proof stress, Yield strength, Ultimate tensile strength or breaking force, Elongation, Reduction of area, modulus of elasticity, etc. 

A.1. Longitudinal Tensile Test
As the name suggest, longitudinal tensile test is performed on the test specimen, which is extracted in the longitudinal direction of the sample of item such as plate or pipe. Longitudinal tensile test is the most common tensile test performed on all types of materials.
AS 1391, AS 2205.2 and ASTM E8 are the most common standards used to perform this test. 

A.2. Transverse Tensile Test
Transverse tensile test is performed on the test specimen, which is extracted in the transverse direction or across the sample of item such as plate or pipe. This test is performed to measure transverse tensile strength, yield strength, proof stress, elongation and reduction of area. The transverse tensile strength is very important mechanical property in pipes and Hoop’s stress calculation.

Transverse tensile test is performed on pipe materials, welded joints and occasionally on pressure vessel plates where design requirements demand. AS 1855, AS 2205.2 and EN 895 are some of the common standards used to perform this test. 

A.3. ‘Z’ Direction Tensile Test
Through thickness tensile test or ‘Z’ direction tensile test is performed to evaluate mechanical properties mostly in steel. The test involves applying tensile forces on a test specimen whose axis is perpendicular to the rolled surfaces of steel plate. The primary purpose of the test is to measure resistance to lamellar tearing by determining reduction of area and ultimate tensile strength in ‘Z’ direction.

EN 10164, ASTM A770, AS 3678, AS 1391 are some of the common standards used to perform test.

or refer to other article in this blog

A.4. Weld Tensile testing
Tensile test is performed on welded test specimen as part of the weld procedure (WPS / WPQR) qualification, welder qualification, weld performance qualification and Production weld qualification. Generally, a transverse tensile test is performed where the weld metal is oriented transverse in the centre of the specimen. A longitudinal tensile test is performed when the weld metal qualification is required or WPS qualification demands.

AS 2205.2, EN 895 and ASME IX QW 150 are some of the common standards applied to perform weld tensile test. 

A.5. Tension test
Tension test is similar as tensile test. The terminology ‘tension test’ is used when the sole purpose of the test is to determine ultimate breaking force or failure load. Tension test is also commonly used to perform proof load test. Occasionally, yield force or deformation force is recorded during tension test. 

A.6. Bond Tension Test
The use of adhesives in engineering applications in progressively increasing. These adhesives are used to bond various metallic panels, protective coatings, wear resistance coatings, etc. The bonding or adhesion on the subsurface is very crucial in engineering application and severe corrosive environment. A coating bond test or adhesive test is performed to measure tensile force required to break or peel off the coating (quantitative test). 

A.7 Proof Load Test
A proof load test is performed on various components to ensure that these components can withstand the design load without failure or without yielding (unacceptable deformation). The test is performed by applying force in the range of 1.1 to 1.5 times of the design load or maximum allowable working load (MAWL) for a specified duration.

TO BE CONTINUED . . . .

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