Cold Water Pipe (HDPE)

Pipe Marking – HDPE Pipe (Cold Water)

Mechanical Properties of HDPE

Properties	HDPE	Units	Standards
Density	0.951	g/cm3	ISO 1183
Melt Mass-Flow Rate (MFR) (190 °C/5.0 kg)	0.58	g/10 min	ISO 1133
Environmental Stress-Cracking Resistance (F0)	1000	Hour	ASTM D1693B
Tensile Stress (Yield)	23.0	MPa	ISO 527- 2/2
Tensile Strain (Break)	600	%	ISO 527- 2/2
Flexural Modulus	850	MPa	ISO 178
Brittleness Temperature	-70.0	°C	ASTM D746
Vicat Softening Temperature	120	°C	ISO 306/A
CLTE – Flow (20 °C to 60 °C)	0.00015	cm/cm/°C	ASTM D696

Hydraulic Properties

The velocity of flow in hdpe pipes does not normally exceed 1-2 meters per second in distribution mains. The hydraulically smooth bore of a hdpe pipe gives excellent flow characteristics through its operational life and the hydraulic friction co-efficient normally used in the design of hdpe pipes working under pressure are:

Colebrook-White k = 0.003 mm
(max 0.01 mm to allow for some deposition with age)
Hazen Williams c = 150
The Colebrook-White based formula is recognized by engineers throughout the world as the most accurate basis for hydraulic design.

The Advantages of HDPE are as follows:

Non-toxic
High impact strength
High resistance against corrosion-internal and external
High chemical resistance
Toughness
Flexibility
Ease of handling and laying
Can be made in long lengths
Excellent resistance against abrasion
No build-up of minerals on inside walls, i.e. crustations
Weather resistance
Expected life of 50 years or more
Smooth surface with low friction losses, i.e. hydraulic smooth C-value (Hazen Williams) = 150-165, K-value (Prandtl – Coalbrook) = 0.007mm
Very low water absorption
No stress cracking
Suitable for high temperature application (PP)