[ Standards ]
[ Standards ]
The PED follows the inspection activities listed in Table 2 .
Material properties testing With the American pressure codes and the EU / UK pressure directives being material based , the common metallurgical testing techniques are very vital to proper compliance . Following is an overview of these techniques .
- Chemical analysis - Optical Emission Spectrometry ( OES ): Optical emission spectrometry has been widely used as a method to control the production of steel and other alloys in primary producing manufacturers such as foundries due to its speed , accuracy , and efficiency . In the case of highly specified cast alloys , OES analysis is a common technique to confirm the chemical composition of a metallic sample . OES allows for the analysis of many elements in a large magnitude of concentrations in a single measurement making it a useful tool to certify high specification cast alloys . Ni , Cr , Cu , Mo , Va are residual elements that can be of concern in certain steel grades for high spec work .
- Tensile testing Tensile testing consists of applying a pulling force on a test material in two opposite directions . This allows us to determine how strong a material is and how much deformation it can withstand . Ultimate tensile strength , elasticity , yield strength , and strain deformation are typical properties reported , but several other characteristics can also be determined . Calculations for yield strength can be affected by the 1.0 or 0.2 offset vs . 0.5 extension under load ( EUL ) between different specification orders and alloy combinations . These tests are generally performed on an electromechanical or universal testing machine and are standardized by ASTM E8 , ASTM A370 , and ISO 6892 . The degree to which a material is tested is governed by the level of specification required by the customer .
- Hardness testing Hardness testing is a way to measure the surface quality of a cast material . It allows for the determination of a material ’ s resistance to permanent indentation in a non-destructive manner .
- Impact testing Impact testing evaluates the amount of work required to rupture a test material in a destructive fashion . The Charpy test is the most used technique
Hydro-Thermal follows precise pressure regulations ( per our PED specifications ) when testing our direct steam injection heaters in-house . Our testing procedure adds air pressure and water to the heaters , ensuring no product leakage will occur once installed .
in measuring this material property for high specification cast alloys .
Table 2 . Common NDE / NDT activities with some positive attributes and some of the limitations that come with the technique . NDE / NDT method
General applications and positive attributes
Limitations
Radiography ( RT )
Magnetic Particle ( MT )
Liquid Penetrant ( PT )
Can be used for ferrous and non-ferrous materials . Has a great reference library from ASTM ( E192 , E186 , E280 , E446 ) for steels . Many different classifications of defects are showcased in the above reference radiographs
Used for ferro-magnetic materials with being extremely sensitive to cracks and does well highlighting larger rounded indications .
Used on non-magnetic materials highlighting cracks of all sizes but is more sensitive when used as a fluorescent method . Does very well with all sizes of rounded indications .
Casting wall thickness vs . thinness and the ability to maintain proper levels of sensitivity . Is not reliable to exhibit cracking and linear indications .
Smaller ( 0.062 ” diameter and smaller indications ) are hard to ascertain . Relies on being able to magnetize with coil or cabling .
Can leave many false indications on the surface of certain alloys . Method is limited to surface evaluation only .
Ultrasonic Testing ( UT ) Must be used on fine grained materials . Larger grained microstructures like austenitic materials and nickel-based alloys lose the back reflections .
Needs very experienced technician to be able to ascertain reflections from the material being tested .
Visual Testing ( VT )
Used to verify cast external and internal surfaces using reference photographs or tactile plates . Easy to use magnification to assist in evaluation .
Can be very subjective to determine conformance to specifications , difficult to find readily available Level III personnel
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