The nominal wall thickness of Ductile Iron Pipe is calculated as a function of the nominal size (NB) utilizing the following formula:

**e** = K (0.5 + 0.001NB)

*where:*

**K** = A coefficient used for the determination of Class thickness and is selected from a series of whole numbers normally from 7 to 14

**e** = The nominal wall thickness of the pipe

**NB** = The nominal bore of the pipe

The Ductile Iron Pipes are supplied in 6m lengths. The standard wall thickness and operating pressures are given below:

PFA – Allowable Operating Pressure

Internal pressure, excluding water hammers, that a component can safely and continuously withstand under hydraulic service.

PMA – Allowable Maximum Operating Pressure

Maximum internal pressure, including water hammer that a component can safely withstand during service.

PEA – Allowable Text Pressure

Maximum hydrostatic pressure that can be applied on site to a newly laid pipe component can withstand for a relatively short duration, when either fixed above ground level or laid and back-filled underground in order to measure the integrity and leak tightness of the pipe.

*e1= The thickness of cement mortar lining**Pipes supplied in container loads will be in 5.5 or 5.7 metre length**A tolerance of +1mm applies**Thicknesses are greater for calculated for “smoothing” between C40 and C30 and also between C30 and C25*