Welded Threaded Pipe Fittings

The standards for Welded Threaded Pipe Fittings mainly include the following aspects:

Appearance quality standard:The surface of the weld seam should be smooth and free from defects such as cracks,lack of fusion,porosity,slag inclusion,splashing,etc.The excess height of the weld seam should be uniform and not exceed the specified value.The outer surface of the steel pipe should be free of obvious scratches,dents,rust and other defects,and the inner surface should be relatively smooth.The depth of local protrusions or pits generally does not exceed 10%of the wall thickness and is not greater than 2mm

Dimensional accuracy standard:The allowable deviation of the outer diameter is usually±0.75%D(D is the outer diameter of the steel pipe),and for high-precision steel pipes,the allowable deviation can be controlled within±0.5%D.The allowable deviation of wall thickness is generally±12.5%t(t is the wall thickness of the steel pipe),and can be controlled within±10%t when there are special requirements.The allowable deviation for the length of steel pipes of fixed length is generally±50mm,and stricter control can also be carried out according to contract requirements

Mechanical performance standards:The tensile strength and yield strength requirements for thick walled spiral welded steel pipes of different materials are different.For example,the tensile strength of Q235 steel pipes should be≥375MPa,and the yield strength should be≥235MPa;The tensile strength of Q345 material steel pipe should be≥470MPa,and the yield strength should be≥345MPa

Process performance standards:including bending test,flattening test,and expansion test.The bending test requires that there should be no cracks on the outer surface and weld seam of the steel pipe after bending.The flattening test requires that the weld seam and base metal should not have cracks,fractures,or other phenomena.The expansion test requires that the steel pipe should not have defects such as cracks or tears after expansion

Non destructive testing:Internal quality inspection is carried out using ultrasonic testing,magnetic particle testing,or penetrant testing to ensure that there are no defects inside the pipe fittings that exceed the standard requirements