Extruded three-layer polypropylene coating on steel pipes

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Extruded three-layer polypropylene coating on steel pipes

Nowadays “FERRUM” S.A. is the main Polish manufacturer of the anticorrosive, extruded, three-layer, polyethylene/polyethylene co- ating on steel pipes. The coating technology allows to obtain the anticorrosive three-layer polyethylene/polyetylene coating, which consist of:

epoxy layer,
copolymer layer (bonding agent),
polyethylene/polypropylene layer.

The coating is applied on steel pipes of diameters from 159 mm to 1420 mm and length from 6 m to 18 m. Properties of applied coatings comply with the following stan- dards:

EN-PN ISO 21809,
DIN 30670,
DIN 30678,
NFA 49-710,
EN-PN 10285.

The anticorrosive coating consists of the following layers:

epoxy layer of minimum thickness of 80 μm,
copolymer layer of minimum thickness of 250 μm,
polyethylene layer of minimum thickness between 1,8 mm and

3,7 mm or polypropylene layer of minimal thickness between 1,8 mm and 2,5 mm.
“FERRUM” S.A. manufactures coated steel pipes in diameter from 159 mm to 1420 mm and length from 6 m to 18 m. We provide coating services with reference to pipes delivered by our custo- mers.

Coating grade	Coating type	Coating thickness depending on the pipe outer diameter [mm]
		159 – 273	323,9 – 457	508 – 559	610 – 762	813 – 1420
Polietylenowa	N-n, S-n	2	2,2	2,5	2,5	3
N-v, S-v	2,7	2,9	3,2	3,2	3,7
Polipropylenowa	standardowa	2	2,2	2,2	2,5	2,5

Note: for the diameters over 1420 mm ”FERRUM” S.A. can make coating by polyethylene tapes acc. to DIN 30672 class B30, C30 and C50.

N-n, N-v coating with low density polyethylene (LDPE) or medium density polyethylene (MDPE) with regular –n and reinforced –v thickness
S-n, S-v coating with high density polyethylene (HDPE) with regular –n and reinforced –v thickness

Anticorrosive coating 3LPE/ 3LPP according to PN-EN ISO 21809-1 is composed of:

epoxy layer of minimum 125 μm thickness,
copolymer layer of minimum 150 μm thickness,
polyethylene or polypropylene layer from 1,8 mm to 4,7 mm.

Layer thickness

g/m	Class A1	Class A2	Class A3	Class B1	Class B2	Class B3	Class C1	Class C2	Class C3
≤15	1,8	2,1	2,6	1,3	1,8	2,3	1,3	1,7	2,1
15≤ C ≤50	2,0	2,4	3,0	1,5	2,1	2,7	1,5	1,9	2,4
50≤ C ≤130	2,4	2,8	3,5	1,8	2,5	3,1	1,8	2,3	2,8
130≤ C ≤300	2,6	3,2	3,9	2,2	2,8	3,5	2,2	2,5	3,2
300 < C	3,2	3,8	4,7	2,5	3,3	4,2	2,5	3,0	3,8

The coating manufacturing process consists of the following operations:

the surface blast cleaning to Sa 2 1/2 acc. to ISO 8501-1,
the electrostatic spraying of epoxy powder onto a heated pipe,
wrapping a pipe with extruded copolymer,
wrapping a pipe with polyethylene/polyetylene in continuous way,
cooling the coating and dressing the pipe ends.

An extruded polyethylene coating has higher mechanical properties in comparison with cold applied polyethylene tape coating. Anticor- rosive coatings made of three-layer PE/PP are characterized by:

high mechanical strength,
high adherence of the coating to the pipe,
guaranteedlong-lastinganticorrosiveprotectionofundergroundpipelines for minimum 50 years,
100% protection of weld zone of coated longitudinally and spirally welded pipes,
suitability for bending of coated steel without damaging the insulation layer.