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Sprial steel pipe,Piling pipe,Stainless steel pipe

38 Terms for Pipes and Fittings(2)


16. 20℃, 50-year confidence lower limit (σLCL):

A stress value used to evaluate material performance, which refers to the confidence lower limit of the predicted long-term strength of the pipe made of the material under internal water pressure at 20℃ and 50 years with a confidence level of 97.5%, in MPa.

17. Long-term hydrostatic strength (σLTHS):

Indicates the average strength predicted at temperature T and time t (the average strength refers to the confidence lower limit of the material strength when the confidence level is 50%), in MPa.

18. 20℃, 50-year long-term strength (σLTHS):

The average strength or predicted average strength of the pipe under water pressure at 20℃ for 50 years, in MPa.

19. Environmental stress cracking:

The phenomenon of accelerated stress cracking due to environmental conditions. The environmental stress cracking resistance of the material is often expressed by ESCR.

20. Degree of crosslinking:

A physical quantity indicating the degree of crosslinking. When cross-linking occurs between polymer chains, it is expressed as the average number of cross-linking units per polymer molecule. It is also called cross-linking point density and cross-linking index. It is usually expressed by gel content.

21. Ductile failure:

Destruction accompanied by obvious awakening deformation.

22. Brittle failure:

Destruction without obvious plastic deformation in the rupture area.

23. Penetration failure:

A form of failure in which the pressurized fluid in the pipe seeps out of the pipe wall to form visible loss but no obvious cracking occurs.

24. Hoop stress:

Stress along the circumference of the pipe caused by internal pressure in the pipe wall.

25. Burst pressure:

The maximum pressure before the pipe ruptures in the hydrostatic burst test of the pipe.

26. Failure temperature:

The highest temperature that occurs when the pipeline system exceeds the control limit.

27. Structural wall pipe:

A general term for pipes with composite wall structures composed of multiple layers of materials and pipes with special-shaped wall structures such as open ribs, closed ribs (hollow), etc.

28. Special-shaped wall pipe:

A general term for pipes with smooth inner wall and spiral, annular or ribbed outer wall.

29. Double-wall corrugated pipe:

The inner wall is smooth and flat, the outer wall is trapezoidal or arc-shaped corrugated ribs, and the inner and outer wall corrugations are hollow special-shaped pipes.