Z-Grade Quality Material (Through Thickness Property)
In the welding process, will produce a voltage (stress) on the parent plate. Where the voltage can cause cracking defects. Crack / opening material having a direction parallel to the metal surface is referred to as lamellar tearing, this defect would cause material damage to the upright position the plate thickness. Lamellar tearing, the dictionary meaning of the word "lamellar" is a thin layer, membrane or plate-shaped network. While the "tear" is interested nicked widened some parts. So that lamellar tearing the material can be interpreted as a result of welding cracks berbetuk material layer located at the surface of the material and the direction of the plate material. Lamellar tearing it generally occurs in rolled steel plate material, where this is a dangerous condition that occurs when a plate material having a low elastic properties (low ductility) is welded perpendicular to the direction of the plate thickness.
This rift can occur where:
- Strain (strain) due to contraction due to temperature changes occur in the plate thickness direction (through thickness direction of plates)
- Or the inclusion / non-metal material inserts in the form of a thin layer of the field where the main form of insertions (planar ) is in line with the pipe surface. So that the strain (strain) due to the contraction will force the inclusion of non-metal earlier as a trigger to form a planar aperture in the direction parallel to the surface of the plate. At welded steel structure, where the position of the load is borne perpendicular to the surface of the plate, lamellar tearing may be the cause initial damage larger structures. At the level of quality steel plate normal, usually testing has been done in the direction rollingnya (elongated plates - the x-axis) and perpendicular to the direction rollingnya (wide plates - the y-axis), and the material properties in the direction perpendicular plate thickness ( z axis) is not mentioned. With special production technology at this time and the reduction of sulfur content, most of the steel manufacturers have capacity to produce steel plates with the property for plate thickness direction (z-axis), wherein the plate with this type of material is referred to as the Z-grade quality. Z-grade Quality Material This minimizes the risk of lamellar tearing, since this material has a resistance (ductility) is more in the direction of thickness compared to the normal quality grade material. To determine the extent of toughness properties (property) material is high grade Z, performed specific tensile test (Z-axis direction) of the sample material, wherein if the high yield area reduction then this material can be considered to have a good quality grade Z. course testing procedures and how much value reduction of at least the area must be obtained so that the material can be categorized good / not, should refer to the applicable industry standards. Several al industry standards: ASTM D7291, EN 10164 or Rule classification bodies such as GL, BV, LR, ABS or DNV also provides test procedures and acceptance criteria for materials with Z-category This high grade. glance when reviewing the GL Rules for Materials and Welding - Section1: Steel Plates, Strips and Bars, wherein there to category Z-grade material is determined based on the resulting area reduction during tensile testing of unidirectional orientation of the sample with thicker materials (such as image above). There are 2 categories of Z-grade material according to GL rules, the Z25 and Z35, where Z25 is if the resulting area reduction of 25% minimum, looking for Z35 reduction resulting area must be a minimum of 35%. Tests were conducted at 3 tensile test specimen ( Z direction), one of which shall be not less than 25% but still must be greater than 20% for the Z25. As for the Z35 one specimen shall be not less than 35% but still must be greater than 25%. use of this material commonly applied to offshore structures, ships or floating units just as FPSO, FSO and FSRU, which is usually used in the structure had vertical load to the plate thickness / material, such as doubler plate at the connection between the deck plate with stool topside production modules.
- Strain (strain) due to contraction due to temperature changes occur in the plate thickness direction (through thickness direction of plates)
- Or the inclusion / non-metal material inserts in the form of a thin layer of the field where the main form of insertions (planar ) is in line with the pipe surface. So that the strain (strain) due to the contraction will force the inclusion of non-metal earlier as a trigger to form a planar aperture in the direction parallel to the surface of the plate. At welded steel structure, where the position of the load is borne perpendicular to the surface of the plate, lamellar tearing may be the cause initial damage larger structures. At the level of quality steel plate normal, usually testing has been done in the direction rollingnya (elongated plates - the x-axis) and perpendicular to the direction rollingnya (wide plates - the y-axis), and the material properties in the direction perpendicular plate thickness ( z axis) is not mentioned. With special production technology at this time and the reduction of sulfur content, most of the steel manufacturers have capacity to produce steel plates with the property for plate thickness direction (z-axis), wherein the plate with this type of material is referred to as the Z-grade quality. Z-grade Quality Material This minimizes the risk of lamellar tearing, since this material has a resistance (ductility) is more in the direction of thickness compared to the normal quality grade material. To determine the extent of toughness properties (property) material is high grade Z, performed specific tensile test (Z-axis direction) of the sample material, wherein if the high yield area reduction then this material can be considered to have a good quality grade Z. course testing procedures and how much value reduction of at least the area must be obtained so that the material can be categorized good / not, should refer to the applicable industry standards. Several al industry standards: ASTM D7291, EN 10164 or Rule classification bodies such as GL, BV, LR, ABS or DNV also provides test procedures and acceptance criteria for materials with Z-category This high grade. glance when reviewing the GL Rules for Materials and Welding - Section1: Steel Plates, Strips and Bars, wherein there to category Z-grade material is determined based on the resulting area reduction during tensile testing of unidirectional orientation of the sample with thicker materials (such as image above). There are 2 categories of Z-grade material according to GL rules, the Z25 and Z35, where Z25 is if the resulting area reduction of 25% minimum, looking for Z35 reduction resulting area must be a minimum of 35%. Tests were conducted at 3 tensile test specimen ( Z direction), one of which shall be not less than 25% but still must be greater than 20% for the Z25. As for the Z35 one specimen shall be not less than 35% but still must be greater than 25%. use of this material commonly applied to offshore structures, ships or floating units just as FPSO, FSO and FSRU, which is usually used in the structure had vertical load to the plate thickness / material, such as doubler plate at the connection between the deck plate with stool topside production modules.
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