3LPP Coated Pipe


What is 3LPP Coated Pipe?

The pipe is coated with a three-layer polypropylene (3LPE) coating composed of a fusion bonded epoxy (FBE) primer, an adhesive layer, and an outer layer of polyethylene to provide resistance to corrosion and long-lasting protection. The three-layer polypropylene coating system is used for buried or submerged pipelines operating at moderate temperatures. This system provides excellent resistance to mechanical damage, gouging, abrasion, and cathodic disbondment. Additionally, the three-layer polypropylene coating has very good adhesion to pipe surface and bond strength between coatings. The fusion bonded epoxy primer provides excellent corrosion resistance while the adhesive layer provides good impact resistance and toughness. The outer layer of polyethylene provides UV resistance and dark color to prevent light reflection.

Table of Contents

The Layers of 3LPP Coated Pipe

The initial layer of a 3LPP (three-layer polypropylene) coating is formed by fusion bonding a high-performance Fusion Bonded Epoxy primer, or FBE primer. The following step is to apply a copolymer that functions as an adhesive. The final step in this process is to apply a polypropylene outer coat. While the inner 3LPP Coating protects the material from chemical damage or decay, it is the outside layer that imparts toughness to the material, making it one of the most durable coating options available.

Property Indicators of 3LPP Coated Pipe

Properties 3LPP Indicators
Minimum Pipe Diameter 90 mm (3.5″)
Maximum Pipe Diameter 1220 mm (48″)
Minimum Recommended Handling & Construction Temperature -20°C
Maximum Recommended Operating Temperature 110°C (buried service)
Bendability Yes

Tests of of 3LPP Coated Pipe

Property Test Description Typical Values
Degree of cure of epoxy resin DIN 30670 ∆Tg according to the manufacturer specifications
Impact Test DIN 30670 ≥ 7 J/mm
Cathodic Disbondment DIN 30670 23°C/ 28 days or 60°C/ 2 days max 7 mm
Peel Strength DIN 30670 > 35 N/cm at 23°C; < 15 N/cm at 70°C

Production Standards of 3LPP Coated Pipe

The Service Life of PP Coated Pipe

Operating Temperature(℃) Expected Minimum Service Life (Year)
23 50
60 50
80 30
90 16
100 8
If the coatings are used at alternating temperatures, their expected service life should be inferred from the values made above.

Cathodic Disbanding

Cathodic stripping is a critical property of pipeline coatings, and its effectiveness is directly connected to the coating’s combined effect with cathodic protection.

Specimen dimensions: 150*150 steel tube wall thickness, two for each trial group (specimen size, solution, and voltage are subject to different requirements according to different standards, only according to domestic industry standards)

      ≤8mm(65℃± 2℃,-3.5V,24h)

      ≤8mm(65℃± 2℃,-1.5V,48h)

      ≤15mm(65℃± 2℃,-1.5V,30d)

Frequency: two samples per second in accordance with industry standards

The primary apparatus includes a cathode stripping experiment box and a micrometer.


Indentation hardness is a term that refers to the hardness of a material as measured by the depth of the indentation or the area of the indentation when the indenter is pushed into the material surface with the prescribed static test force. General head diameter 1.8mm, cross-sectional area 2.5m square meters.

      ≤0.2mm(23℃± 2℃)

      ≤0.3mm(70℃± 2℃)

Requirements for frequency standards, three samples per time, sample thickness of 2mm.

The test was conducted over a 24-hour period. The Three Layer Polypropylene (3LPP) technology is used in pipelines working in the -20 to +110oC temperature range. The two systems typically have a thickness of 1.5 to 3mm.

Marking & Packaging of 3LPP Coated Pipes

- Marking:

  • 3LPP Pipe Coating is delivered with marking in accordance with industry standards and client requests.
  • Marking is accomplished by the application of paint to the ends of pipes.
  • On the bundle’s tags, the same data, as well as extra information based on the customer’s request, is provided.

- Packaging

  • 3LPP Pipe Coating is packaged in hexagonal or circular bundles that are secured with steel strips.
  • Bundle weight – up to 5000 kg upon customer request.
  • Each bundle includes three tags.

What is PP Coating?

Polypropylene, often known as PP material, is a colorless, odorless, non-toxic, transparent solid substance that is not flammable. It is also non-flammable since it has no odor. This particular plastic has a density of just 0.90 –” 0.91g /cm3, making it one of the lightest types of plastics currently available on the market. When subjected to high temperatures and oxidation under 80°C it may tolerate corrosion by acids, alkalis, salt solutions, and a range of organic solvents, but when exposed to higher temperatures and oxidation it can break down.

The compound is also highly water-resistant, with an absorption rate of around 0.01 percent and a molecular weight of approximately 81 million 150 million. However, owing to the shrinkage rate (1 percent to 2.5 percent), it is not suited for use due to its excellent molding properties. It is difficult to attain the requirements required for some of the higher dimensional precision pieces when using thick wall items since they have a propensity to droop. A high level of surface shine is also required.

In addition to being a thermoplastic synthetic resin with excellent qualities, polypropylene is also used in a range of applications. Since its inception, polypropylene has been extensively developed and employed in a variety of areas, including machinery, automobiles, electronics, and electrical appliances, construction, textiles, packaging, agriculture, forestry, fishing, and the food industry, to name a few. Its chemical resistance, heat resistance, electrical insulation, high strength mechanical qualities, and excellent high wear-resisting processing properties have made it a preferred option for a wide range of applications in several industries.

History of the Development of PP Materials

The notion of directed polymerization was initially proposed by G. Natta, who was the first to effectively polymerize propylene into polypropylene (using aluminum chloride and titanium as catalysts), and he was also the first to popularize the concept.

Production units for polypropylene with capacities of 6000 metric tons per year and 9000 metric tons per annum were built by Italian and American companies, respectively, in 1957.

Polypropylene saw a period of fast expansion from the late 1960s to the mid-1970s, which lasted just a few decades.

Because of advancements in polypropylene yield throughout the 1980s, it is now just marginally lower than polyethylene yield, putting it in second position overall among synthetic resins and only slightly lower than polyethylene yield.

The People’s Republic of China started exploring the process of polypropylene manufacturing in 1962, and the results were published in 1962. Since the 1980s, the use of polypropylene has increased at an exponential pace in China. As a consequence of the introduction of contemporary polypropylene manufacturing technology and equipment in China, the nation has seen a large growth in its production volume and has entered a period of fast expansion. Its overall production capacity was 12.967 million tons in 2012, according to the International Energy Agency (million tons). In 2015, the production capacity of polypropylene was 20.13 million tons per year.

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