# General terms used to pipe and pipe fittings

Nominal diameter (DN)

Calibration of thermoplastic piping system pipe diameter, pipe diameter, outside diameter size or its approximation.

Ring to the bending stiffness/ring stiffness

A measure of the pipe ring resistance to deformation ability. Test method can be used or fixed value calculation method of unit is N/m2 or KN/m2.

Elastic deformation rate in diameter

Pipe under outer pressure load, pipe diameter vertical wall section before the value of the elastic deformation and load center shaft diameter ratio. Expressed in percentage, be determined by the flattening test.

Out of roundness

In the pipe of the same cross-sectional measurement difference of minimum and maximum overall diameter diameter.

Standard size ratio (SDR)

Pipe nominal diameter and the ratio of nominal wall thickness. The SDR = DN/en.

The maximum working pressure (MOP)

Allows continuous use of fluid in pipe system of the maximum effective pressure, unit is the MPa.

Nominal wall thickness en

Pipe wall thickness of the specified value, the unit is mm.

Always use the coefficient C (design)

The total coefficient of a numeric value greater than 1, it takes into account the was not in the prediction of conditions of use and the lower limit of pipeline accessories such as part of nature in the system.

Prediction confidence lower limit hydrostatic strength (sigma LPL)

The confidence level of 97.5%, corresponding to the temperature T and the lower limit of the predicted value of the time T hydrostatic strength, sigma LPL = sigma (T, T, 0.975), the unit for the MPa.

Minimum required strength (MRS)

To 20 ℃, 50 years of sigma LPL confidence lower limit value according to the R10 or R20 series rounded down to the most close to a priority to get the stress value of units for the MPa. When the sigma LPL is less than 10 mpa, according to the R10 series roundness, when sigma LPL is greater than or equal to 10 mpa according to the R20 series of roundness.

Design stress sigmas

The prescribed application allowed under the condition of stress, MRS divided by the coefficient C, rounded to the next smaller values of priority the R20 series, namely the sigma s = (MRS)/C.

The allowable deviation/limit deviation

Allow the limit deviation between numerical values and rules. E. the difference between the maximum allowable values and called on the deviation, e. deviation is called the minimum allowable values and deviation.

The tolerance

Quantity allowed deviation, represented by the difference between the minimum and maximum allowed value. Is equal to the difference between upper and lower deviation.

As a little outside diameter

Outer diameter pipes of a cross-sectional survey, the unit is mm.

The average diameter of

Corresponding to the central circle diameter of the tube wall section. Average diameter is equal to the difference between the average average diameter and wall thickness, average or average diameter and wall thickness, the sum of the unit is mm.

The confidence lower limit (20 ℃, 50 years sigma LCL)

Stress value of the one for the evaluation of materials performance refers to the materials of pipes in 20 ℃, 50 years of water pressure, the confidence level of 97.5%, the prediction of the long-term strength of the confidence lower limit, the unit for the MPa.

Long term hydrostatic strength (sigma LTHS)

Said to predict the average temperature T and time T intensity (average intensity refers to the confidence level of 50% confidence lower limit of strength of materials), unit of MPa.

20 ℃, 50 years long-term strength (sigma LTHS)

Pipe in 20 ℃ water pressure under 50 years of average intensity or predict the average intensity, units for the MPa.

Environmental stress cracking

Due to the influence of environmental conditions and accelerated stress cracking phenomenon. Environmental stress cracking resistance of the commonly used material ESCR said.

Degree of crosslinking

Said the crosslinking degree of physical quantities. When the crosslinking between the polymer chains, with each unit of crosslinked polymer molecules averages said. Also called junction, crosslinking density index. Normally expressed as gel content.

Ductile damage

Awaken with obvious deformation damage.

Brittle failure

There is no obvious plastic deformation damage fracture area.

Seepage failure

In-pipe pressurized fluid seepage wall form visible loss but not obvious cracking destruction form.

Hoop stress

Internal pressure in the pipe wall caused by stress along the pipe circumference direction.

Burst pressure

Before the tubing pipe burst in static hydraulic blasting test of the maximum pressure.

Fault temperature

Pipe system is beyond control limit of maximum temperature.

The structure wall pipe

Composed of multilayer material composite wall structure and wall opening for ribbed, closed ribbed (hollow), and other special pipe wall structure.

Different wall tube

Inner surface is smooth, the outer wall is spiral, annular or Xuan ribbed pipe wall structure.

Double-wall corrugated pipe

Wall smooth level off, the outer wall of trapezoidal corrugated ribs or arc, between the inner and the outer wall corrugated for hollow wall pipes.

Annular ribbed tube

The outer wall of tube wall smooth level off, have a circular strengthening rib deformed tube wall of tubing.

Spiral ribbed tube

The outer wall of tube wall smooth level off, the strengthening rib spiral, special wall pipe made of spiral winding process.

Flat wall tube

The outer wall of tube wall smooth homogeneous wall pipes.

Mechanical connection pipe fittings

Through mechanical connection methods (such as threaded connections, conformity of connection, etc.) realizes the connection pipe fittings.

Elastic sealed pipe fittings

With elastic sealing ring seal connection pipe. Usually can't pass the axial load.

Solvent adhesive type pipe fittings

By solvent adhesive connection pipe fittings.

Fused fittings

In the connection surface (under) the preset electric heating element of pipe fittings.

Hot melt docking pipe fittings

Have the same port, and stay connected pipes size by hot melt welding connection pipe fittings.

Hot melt socket pipe fittings

With the inner surface of the heating tool heating pipe socket and the pipe or valve insert the outside surface, and then insert the merge each other welding, so as to realize the mutual connection of pipe fittings

Standard size ratio (SDR)

Pipe nominal diameter and the ratio of nominal wall thickness. The SDR = DN/en.

The maximum working pressure (MOP)

Allows continuous use of fluid in pipe system of the maximum effective pressure, unit is the MPa.

Nominal wall thickness en

Pipe wall thickness of the specified value, the unit is mm.

Always use the coefficient C (design)

The total coefficient of a numeric value greater than 1, it takes into account the was not in the prediction of conditions of use and the lower limit of pipeline accessories such as part of nature in the system.

Prediction confidence lower limit hydrostatic strength (sigma LPL)

The confidence level of 97.5%, corresponding to the temperature T and the lower limit of the predicted value of the time T hydrostatic strength, sigma LPL = sigma (T, T, 0.975), the unit for the MPa.

Minimum required strength (MRS)

To 20 ℃, 50 years of sigma LPL confidence lower limit value according to the R10 or R20 series rounded down to the most close to a priority to get the stress value of units for the MPa. When the sigma LPL is less than 10 mpa, according to the R10 series roundness, when sigma LPL is greater than or equal to 10 mpa according to the R20 series of roundness.

Design stress sigma s

The prescribed application allowed under the condition of stress, MRS divided by the coefficient C, rounded to the next smaller values of priority the R20 series, namely the sigma s = (MRS)/C.

The allowable deviation/limit deviation

Allow the limit deviation between numerical values and rules. E. the difference between the maximum allowable values and called on the deviation, e. deviation is called the minimum allowable values and deviation.

The tolerance

Quantity allowed deviation, represented by the difference between the minimum and maximum allowed value. Is equal to the difference between upper and lower deviation.

As a little outside diameter

Outer diameter pipes of a cross-sectional survey, the unit is mm.

The average diameter of

Corresponding to the central circle diameter of the tube wall section. Average diameter is equal to the difference between the average average diameter and wall thickness, average or average diameter and wall thickness, the sum of the unit is mm.

The confidence lower limit (20 ℃, 50 years sigma LCL)

Stress value of the one for the evaluation of materials performance refers to the materials of pipes in 20 ℃, 50 years of water pressure, the confidence level of 97.5%, the prediction of the long-term strength of the confidence lower limit, the unit for the MPa.

Long term hydrostatic strength (sigma LTHS)

Said to predict the average temperature T and time T intensity (average intensity refers to the confidence level of 50% confidence lower limit of strength of materials), unit of MPa.

20 ℃, 50 years long-term strength (sigma LTHS)

Pipe in 20 ℃ water pressure under 50 years of average intensity or predict the average intensity, units for the MPa.

Environmental stress cracking

Due to the influence of environmental conditions and accelerated stress cracking phenomenon. Environmental stress cracking resistance of the commonly used material ESCR said.

Degree of crosslinking

Said the crosslinking degree of physical quantities. When the crosslinking between the polymer chains, with each unit of crosslinked polymer molecules averages said. Also called junction, crosslinking density index. Normally expressed as gel content.

Ductile damage

Awaken with obvious deformation damage.

Brittle failure

There is no obvious plastic deformation damage fracture area.

Seepage failure

In-pipe pressurized fluid seepage wall form visible loss but not obvious cracking destruction form.

Hoop stress

Internal pressure in the pipe wall caused by stress along the pipe circumference direction.

Burst pressure

Before the tubing pipe burst in static hydraulic blasting test of the maximum pressure.

Fault temperature

Pipe system is beyond control limit of maximum temperature.

The structure wall pipe

Composed of multilayer material composite wall structure and wall opening for ribbed, closed ribbed (hollow), and other special pipe wall structure.

Different wall tube

Inner surface is smooth, the outer wall is spiral, annular or Xuan ribbed pipe wall structure.

Double-wall corrugated pipe

Wall smooth level off, the outer wall of trapezoidal corrugated ribs or arc, between the inner and the outer wall corrugated for hollow wall pipes.

Annular ribbed tube

The outer wall of tube wall smooth level off, have a circular strengthening rib deformed tube wall of tubing.

Spiral ribbed tube

The outer wall of tube wall smooth level off, the strengthening rib spiral, special wall pipe made of spiral winding process.

Flat wall tube

The outer wall of tube wall smooth homogeneous wall pipes.

Mechanical connection pipe fittings

Through mechanical connection methods (such as threaded connections, conformity of connection, etc.) realizes the connection pipe fittings.

Elastic sealed pipe fittings

With elastic sealing ring seal connection pipe. Usually can't pass the axial load.

Solvent adhesive type pipe fittings

By solvent adhesive connection pipe fittings.

Fused fittings

In the connection surface (under) the preset electric heating element of pipe fittings.

Hot melt docking pipe fittings

Have the same port, and stay connected pipes size by hot melt welding connection pipe fittings.

Hot melt socket pipe fittings

With the inner surface of the heating tool heating pipe socket and the pipe or valve insert the outside surface, and then insert the merge each other welding, so as to realize the mutual connection of pipe fittings.

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