Pressure - B

Pressure - B

What is the recommended maximum operating pressure for a PE pipe?

The relationship between the maximum operating pressure (MOP), the minimum required strength of the PE pipe grade (MRS) and the pipe geometry (SDR standard dimension ratio) is given by the following industrially recognised and applied formula;

MOP = (20 x MRS) / (C x (SDR-1))

Where C is the ‘overall service (design) coefficient, or Safety Factor.

It is generally recommended by our customers and design institutes that for water applications the minimum value of C is 1.25 and for gas applications the minimum value of C is 2.0. The designer may apply higher coefficients depending upon national codes of practice or judgment of local conditions and the critical nature of the application.

Example 1: What is the maximum operating pressure of a PE100 SDR11 water pipeline?

MOP = (20 x MRS) / (C x (SDR-1))

MRS = 10 MPa, SDR = 11, C = 1.25

MOP = (20 x 10) / (1.25 x (11-1))

MOP = 16 bar

Example 2: What is the maximum operating pressure of a PE100 SDR17 gas distribution main?

MRS = 10 MPa, SDR = 17, C = 2.0

MOP = (20 x 10) / (2.0 x (17-1))

MOP = 6.25 bar

(Note, other factors such as resistance to rapid crack propagation (RCP) are suggested to be taken into account, particularly for gas applications, to confirm that the calculated MOP can be applied. Refer to EN 1555 and ISO 4437)

References

EN ISO 12162:1995 Thermoplastics materials for pipes and fittings for pressure applications – Classification and designation – overall Service (Design) coefficient
EN 1555:2002 Plastics piping systems for the supply of gaseous fuels. Polyethylene (PE).
ISO 4437:1997 Buried polyethylene (PE) pipes for the supply of gaseous fuels - Metric series - Specifications

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