Minimum thickness of 3 layer polyethylene coating

Minimum thickness of 3 layer polyethylene coating

DIN 30670 – Polyethylene coatings for steel pipes and fittings

Nominal size of pipe

Minimum thickness of normal coating, in mm
Up to DN100


Over DN100 up to DN250

Over DN250 up to below DN500


From DN500 up to below DN800

From DN800


The minimum coating thickness shall be 0.7mm greater where coatings will be subjected to particularly high mechanical stress.

Along any 1 m length of pipe, the coating thickness may be up to 10% less than the minimum required, provided the thinner area does not cover more than 5 cm2

ISO 21809-1 Petroleum and natural gas industries – External coating for buried or submerged pipelines used in pipeline transportation systems – Part 1: Polyolefin coating (3-layer PE and 3-layer PP)

Coating classes and design temperature ranges

Coating class

AB  C  a
Top layer materialLDPEMDPE/HDPE


Design temperature ranges (℃)

-20 to +60-40 to +80

-20 to +110

a Installation and transportation at temperature below 0 ℃ can cause mechanical damage

Minimum total coating thickness



Total coating thickness a

Class A1 b

Class A2 cClass A3 dClass B1 bClass B2 cClass B3 dClass C1 bClass C2 cClass C3 d
Pm ≤


15< Pm ≤50

50<Pm ≤130
130<Pm ≤ 3002.


300 <Pm


a  The required total coating thickness may be reduced by a maximum of 10 % on the weld seam for SAW welded pipes.

b  Class 1 is for light duty (onshore sandy soil)

c   Class 2 is for moderate duty (clay soils, absence of backfill)

d  Class 3 is for heavy duty (rocky soil or offshore)