ISO 6993-1:2006 ガス燃料供給用の埋設された耐衝撃性ポリ（塩化ビニル）（PVC-HI）配管システム—パート1：最大動作圧力1 bar（100 kPa）の配管 | ページ 2

3.1.1

nominal outside diameter

d_n

numerical designation of size which is common to all components in a thermoplastics piping system other than flanges and components designated by thread size

Note 1 to entry: It is a convenient round number for reference purposes.

Note 2 to entry: For metric pipes conforming to ISO 161-1, the nominal outside diameter, expressed in millimetres, is the minimum mean outside diameter d_{em, min}.

3.1.2

mean outside diameter

d_em

measured length of the outer circumference of the pipe divided by π, rounded up to the nearest 0,1 mm

Note 1 to entry: The value for π is taken to be 3,142.

3.1.3

minimum outside diameter

d_e,min

minimum value of the mean outside diameter

Note 1 to entry: It is equal to the nominal outside diameter d_n, expressed in millimetres.

3.1.4

maximum outside diameter

d_e,max

maximum value of the mean outside diameter

3.1.5

outside diameter at any point

d_e

measured outside diameter through the cross-section at any point of the pipe, rounded up to the nearest 0,1 mm

3.1.6

out-of-roundness

difference between the measured maximum outside diameter and the measured minimum outside diameter in the same cross-sectional plane of the pipe

3.1.7

nominal wall thickness

e_n

wall thickness, in millimetres, tabulated in ISO 4065, corresponding to the minimum wall thickness, e_min, at any point

3.1.8

mean wall thickness

e_m

arithmetic mean of at least four measurements regularly spaced around the same cross-sectional plane of the pipe, including the measured minimum and maximum values obtained, rounded up to the nearest 0,1 mm

3.1.9

wall thickness at any point

e

measured wall thickness at any point around the circumference of the pipe, rounded up to the nearest 0,1 mm.

3.1.10

standard dimension ratio

SDR

Note 1 to entry: It is a convenient round number for reference purposes.

3.2.1

high-impact poly(vinyl chloride)

PVC-HI

mixture of unplasticized PVC and an impact-resistance modifier

3.2.2

lower confidence limit of the predicted hydrostatic strength

σ _LPL

quantity with the dimensions of stress, which represents the 97,5 % lower confidence limit of the predicted hydrostatic strength for a single value at a temperature T and a time t

Note 1 to entry: It is denoted as σ_LPL = σ(T, t, 0,975).

3.2.3

minimum required strength

MRS

value of σ_LPL, at a temperature of 20 °C and a time 50 years, σ(20, 50 years, 0,975), rounded down to the next smaller value of the R 10 series or of the R 20 series conforming to ISO 3 and ISO 497, depending on the value of σ_LPL

3.2.4

overall service [design] coefficient

C

overall coefficient with a value greater than 1, which takes into consideration service conditions as well as properties of the components of a piping system other than those represented in the σ_LPL

3.3.1

natural gas

gaseous fuel containing a mixture of hydrocarbons, primarily methane, but generally also including ethane, propane and higher hydrocarbons in much smaller amounts, as well as some inert gases such as nitrogen and carbon dioxide, plus minor amounts of trace constituents

Note 1 to entry: Natural gas remains in the gaseous state under the temperature and pressure conditions normally found in service.

3.3.2

pressure

overpressure relative to atmospheric pressure

3.3.3

maximum operating pressure

MOP

maximum effective pressure of the gas in a piping system, expressed in bars, which is allowed in continuous use

Note 1 to entry: It takes into account the physical and the mechanical characteristics of the components of the piping system.