Welded Threaded Pipe Fittings

During the use of Welded Threaded Pipe Fittings,different types of failures may occur due to various factors.The following is a detailed introduction for you:

Loose connection

reason

Improper installation:If the threaded fittings are not tightened according to the specified torque or the threads are not aligned correctly during installation,it is easy to cause loose connections.During the operation of the pipeline system,due to factors such as vibration and pressure changes,the connection parts of the fittings will gradually loosen.

Vibration impact:Pipeline systems will generate vibrations during operation,such as pump operation,fluid flow,etc.Long term vibration can reduce the frictional force of threaded connections,leading to gradual loosening of pipe fittings.

Temperature change:The temperature change of the medium inside the pipeline can cause thermal expansion and contraction of the pipe fittings.If the material of the pipe fittings is different,there will be differences in the coefficient of thermal expansion.When the temperature changes,the threaded connection will be subjected to additional stress,resulting in loose connections.

Harm:Loose connections can cause leaks in the pipeline system,not only wasting media,but also potentially leading to safety accidents.For example,leaked flammable and explosive media may cause dangers such as fires and explosions.

leak

reason

Sealing failure:Sealing material is the key to ensuring the sealing performance of threaded pipe fittings.If the sealing material is selected improperly,aged,damaged,or installed incorrectly,it can lead to seal failure and leakage.For example,rubber gaskets may lose their elasticity after long-term use,and PTFE sealing tape may be damaged or improperly wrapped.

Thread damage:Threads may be worn,corroded,or damaged by external forces during use,resulting in a decrease in the fitting accuracy of the threads and an inability to form an effective seal.For example,during installation or disassembly,improper use of tools may scratch the threads;In environments with corrosive media,threads are prone to corrosion.

Excessive pressure:When the pressure inside the pipeline system exceeds the design pressure of the threaded fittings,it will affect the sealing performance of the fittings,which may cause the sealing parts to rupture or deform,resulting in leakage.

Hazard:Leakage can cause medium loss and affect the normal operation of pipeline systems.For some toxic,harmful,flammable and explosive media,leakage can also pose a serious threat to the environment and personnel safety.

Thread damage

reason

Wear and tear:During the installation and disassembly of threaded fittings,friction occurs between the threads,and long-term friction can cause surface wear of the threads,resulting in shallower tooth profiles and smaller outer diameters,affecting the fitting accuracy and connection strength of the threads.

Corrosion:If the medium transported by the pipeline is corrosive,or if the environment in which the pipe fittings are located is humid and contains corrosive gases,the threads will be corroded.Corrosion can cause rust spots and pits on the surface of threads,and in severe cases,it can lead to thread fracture.

Overload:When the external force borne by threaded fittings exceeds their load-bearing capacity,such as excessive tightening or significant tension,pressure,etc.,it can cause thread deformation or fracture.

Harm:Thread damage can cause pipe fittings to be unable to connect properly or not firmly connected,affecting the stability and sealing of the pipeline system.Severe thread damage may require replacement of fittings,increasing repair costs and time.

corrosion

reason

Chemical corrosion:The medium transported by pipelines may contain various chemical substances,such as acids,alkalis,salts,etc.,which can react chemically with the material of the pipe fittings,leading to corrosion of the fittings.For example,in the pipeline system of the chemical industry,the transported chemical medium has strong corrosiveness and is prone to corrode threaded fittings.

Electrochemical corrosion:When metal pipes of different materials come into contact with each other and are in a humid environment,they will form primary batteries and undergo electrochemical corrosion.For example,when connecting carbon steel pipe fittings with stainless steel pipe fittings,if effective insulation measures are not taken,electrochemical corrosion is prone to occur in humid environments.

Environmental factors:The environmental conditions in which the pipe fittings are located can also affect their degree of corrosion.In marine environments,the air contains a large amount of salt,which can accelerate the corrosion of pipes;In high temperature and high humidity environments,pipe fittings are also prone to rusting and corrosion.

Harm:Corrosion can cause thinning of the wall thickness and reduced strength of the pipe fittings,affecting their service life.Meanwhile,corrosion products may clog pipelines,affect the flow of media,and even cause damage to other equipment in the pipeline system.

crackle

reason

Welding defects:For welding threaded fittings,if the welding process is improper,such as excessive welding current,fast welding speed,uneven cooling of the weld seam,cracks will occur at the weld seam.These cracks may gradually propagate during the operation of the pipeline system,leading to the rupture of the pipe fittings.

Stress concentration:During the processing,installation,or use of pipe fittings,stress concentration may occur due to unreasonable structural design,improper installation,and other reasons.Cracks are prone to occur in areas of stress concentration.For example,bends,tees,and other parts of pipe fittings are prone to stress concentration due to changes in fluid flow.

Fatigue damage:During operation,pipeline systems are subjected to periodic pressure changes,vibrations,and other effects,causing fatigue damage to pipe fittings.Long term fatigue can cause cracks on the surface of pipe fittings and gradually propagate.

Harm:Cracks can seriously weaken the strength and sealing of pipe fittings.Once the cracks propagate to a certain extent,the pipe fittings may suddenly rupture,leading to the failure of the pipeline system and causing serious safety accidents.