In order to satisfy increasing demand by the thermal hydraulic and plant engineering industries, the new GK COLOR project has been designed to provide customers with painted steel pipes.

GK COLOR is ready to install, in compliance with the standard related to the identification of conveyed fluids through-colour coded pipes, and simultaneously saves installers expensive painting costs.

Pipes for general applications are normally available in two standard colours.
The basic product is varnished with one coat, but two or more hands can be applied if required.


Product types: pipes of circular cross-section for domestic or industrial installations and for the construction of scaffolding or structures.
Dimensions: all external diameters, varying from a minimum of 17.2 mm to a maximum of 219.1 mm.
Pipe lenghts: all lengths are available, from a minimum of 4500 to a maximum of 7000 mm.
Mass per unit length: maximum allowed 40kg/m.


The finishing layer forming the upper film is a water-soluble high solids thermosetting melamine-based coating. Besides being highly resistant to atmospheric agents, it also has guaranteed adhesion and anti-abrasion properties, is totally free from 'chalking' effects and discolouration over time, and is devoid of substances that are toxic for the environment and for the health of its users.
Gloss: UNI EN ISO 2813 test: 60 Gloss for all RAL colours
Discolouration: UNI EN 13523 - Part 22 outdoor exposure: no variation after 280 days
UV resistance test: UNI EN 13523 test - Part 21 outdoor exposure: decrease of less than 10 gloss after 1000 hours
Hardness: UNI 10782 test: 2H
Adhesion: DIN EN ISO 2409 grid test: 100% GTO
Cupping: DIN EN ISO 6272 test: 10 mm
Curvature: minimum radius of curvature four times the external diameter of the pipe (in the bending test using a radius of curvature equal to three times the external diameter, the film showed no chipping).
Bending: DIN EN ISO 6860 conical mandrel test - no cracking.
Humidistat resistance: ASTM D2247-10 test: more than 300 hours
Salt spray (fog) resistance: DIN EN ISO 4628 / ASTM B 117: no variation after 300 hours
Maximum continuous operating temperature: -40°C +150°C
aximum temperature for short periods: +250°C


The prodution process of GK color pipes is fully automatic. Operator intervention is limited to the loading of pipe bundles, the settings , quality controls and the unloading of the finished product.
The pipes are sandblasted externally using a spherical grit to achieve an SA class 2.5 finish, ensuring perfect adhesion of the coating and producing a smooth surface finish with low roughness.
After the painting process, the coating thickness is checked and the pipe is then marked according to the required specifications. The finished pipes are then packed in hexagonal bundles and fastened with four metal straps.


GK color pipes can be cut, drilled, threaded and cold bent without seriously damaging the coating. Hot work processes such as blowpipe cutting and various types of welding only cause limited burning to the coating, approximately 20 - 30 mm from the relative point.
The film may be restored simply by brushing the relative point to remove any remaining burn marks, and if needed, by sand-papering it, and finally, by applying the appropriate GK color product, which is available in can or spray can form.


GK color pipes are considered as non-hazardous special waste and can be recycled. They can be sent to collection points for ferrous metals and can be recycled as normal un-coated pipes.
The identification code is 12.01.01.


Standard colours

Standard colour * Content RAL
Green Water RAL 6032
RAL 6029
RAL 6024
Silver grey Vapour and overheated water RAL 9006
Brown Mineral oils, vegetable and animal oils, liquid fuels and/or inflammable substances RAL 8007
RAL 8002
RAL 8003
RAL 8024
Ochre yellow Gaseous or liquified gases (excluding air) RAL 1024
Orange Acids RAL 2010
RAL 2009
RAL 2008
Light violet Acids MUNSELL 5P 7/8
MUNSELL 2.5P 7/8
MUNSELL 2.5P 7/6
Light blue Air MUNSELL 5PB 7/8
MUNSELL 2.5 PB 7/8
MUNSELL 2.5 PB 7/6
Black Other fluids RAL 9004
Red Fire extinguishing RAL 3000
RAL 3020
RAL 3002
RAL 3001
White Combustible fluids RAL 9003
Yellow Hazardous fluids RAL 1021
RAL 1018
RAL 1023
* The above colour samples are purely indicative and only the content definition is binding


Pipe colour identification

Content RAL colour
Air RAL White 9010
Combustible gases (acetylene, butane, natural or methane gas, propane, oxygen) RAL Yellow 1021 (yellow/red)
Acids (cyanide, acetic acid, acid salt solutions, sulphuric acid) RAL Orange 2000
Oils (excluding fuel) RAL Orange 2003
Water vapor (district heating, heated vapour, condensed vapour)
Hot water
Circulation systems
Fire extinguishing systems
RAL Red 3000
Water (fresh water, waste water, lake water, hot water, cold water)
Usable rainwater
RAL Green 6018
Dry and wet solids RAL Red/Brown 8015
Combustible liquids (acetone, alcohol, fuel, petrol, diesel, heating oil) RAL Brown 8001 (brown/red)
Alkalis (caustic soda, ammonia, potassium carbonate, sodium bicarbonate, soda, foam)
Acids and alkalis
RAL Violet 4001
Fresh water
Cold water
RAL Blue 5015
Air (compressed air, hot air, pressed air, waste air)
Non-combustible gases
RAL Grey 7001
Vapour RAL Silver 9006
Non-combustible gases (carbon dioxide, nitrogen, chlorine, noble gas, argon, helium, ozone, inert gas)
Non combustible liquids (wine, beer, milk, disinfectant liquid)
Dirty water
Protected rainwater
Water solutions
Other liquids
RAL Black 9005 (yellow/black)
Black RAL 9005 (brown/black)
Black RAL 9005