Welded Threaded Pipe Fittings

The quality inspection of Welded Threaded Pipe Fittings covers multiple aspects,including appearance,size,thread,welding quality,performance,etc.The following are the specific inspection contents and methods:

Appearance inspection

Visual inspection:By directly observing the surface of the pipe fittings with the naked eye,check for cracks,sand holes,pores,slag inclusions,burrs,burrs,severe rust,and other obvious surface defects.The surface of the pipe fittings should be smooth and flat,without obvious unevenness or deformation.

Surface roughness detection:Use a surface roughness template or roughness measuring instrument to compare or measure the roughness of the pipe surface,ensuring that it meets the design and relevant standard requirements.

Size inspection

Measurement of pipe diameter and wall thickness:Use measuring tools such as calipers and micrometers to measure the outer diameter,inner diameter,and wall thickness of the pipe fittings.During measurement,multiple points should be taken at different parts of the pipe fittings to ensure that the dimensions are within the allowable tolerance range.

Length and angle measurement:Use a ruler or tape measure to measure the length of the pipe fitting,and use a protractor to measure the angle of the pipe fitting,such as the bending angle of an elbow,to check if it meets the design dimensions.

Groove size inspection:For pipe fittings with grooves,use groove gauges and other tools to check whether the angle,depth,and width of the groove meet the welding process requirements.

Thread detection

Thread gauge testing:Use thread gauges and stop gauges that match the thread specifications of the pipe fittings for testing.The gauge should be able to be smoothly screwed into the thread,and the depth of the gauge screwed into the thread should not exceed the specified number of turns,in order to determine whether the size and accuracy of the thread are qualified.

Thread surface quality inspection:By visual inspection or using a magnifying glass,observe whether there are defects such as missing teeth,broken teeth,burrs,and loose threads on the thread surface.The thread should have a complete tooth profile and a smooth surface.

Welding quality inspection

Non destructive testing

Radiographic testing:Using X-rays or gamma rays to irradiate the weld seam,inspect for defects such as porosity,slag inclusion,lack of penetration,cracks,etc.inside the weld seam based on the image displayed on the film.

Ultrasonic testing:By propagating ultrasonic waves in the weld seam,it determines whether there are defects inside the weld seam based on the reflected waves,and is sensitive to defects such as internal cracks.

Magnetic Particle Testing:Suitable for fittings made of ferromagnetic materials,by applying magnetic particles on the surface of the weld,observing the aggregation of magnetic particles,and detecting defects such as cracks on the surface and near surface of the weld.

Penetration testing:Coating a penetrant containing colored dyes or fluorescent agents on the surface of the weld seam to allow it to penetrate into the defects,then removing excess penetrant,and applying a developing agent to determine whether there are open defects on the surface of the weld seam based on the traces displayed on the developing agent.

Metallographic analysis:Samples are taken from the welds and heat affected zones of the pipe fittings for metallographic analysis.By observing the metallographic structure,checking the crystallization of the weld seam,whether there are defects such as overheating and overburning,and evaluating the influence of welding process on material properties.

Performance testing

Pressure test

Hydrostatic test:Fill the pipe fittings with water,apply a certain pressure,maintain it for a specified time,and observe whether there is any leakage,deformation,or other phenomena in the pipe fittings.The test pressure is usually about 1.5 times the working pressure.

Pneumatic test:For some pipe fittings that are not suitable for hydrostatic testing,pneumatic testing can be used.Fill the pipe fittings with compressed air,apply the specified pressure,and check the surface of the pipe fittings for any air leakage using soap water,etc.

Airtightness test:Fill the pipe with a certain pressure of gas,then immerse the pipe in water or use other airtightness testing methods to observe whether there are bubbles emerging,in order to check the sealing of the pipe.

Mechanical performance test:Samples are taken from the pipe fittings for tensile testing,bending testing,impact testing,etc.,to test the mechanical performance indicators such as tensile strength,yield strength,elongation,bending performance,and impact toughness of the pipe fittings,ensuring that they meet the material and usage requirements.