Pipelines are used to carry water, oil, and gas from one place to another. These pipelines are made of steel, and steel can get rust very easily if it is not protected. To stop corrosion, special coating systems are used. Two of the most common coating systems are 3LPE (Three Layer Polyethylene) and 3LPP (Three Layer Polypropylene).

Both coating systems have three layers: FBE (Fusion Bonded Epoxy), adhesive, and outer layer. These layers protect the steel pipe from damage, moisture, and chemicals. But both coatings are used in different temperature conditions.

In this article, we will explain the difference between 3 LPE vs 3LPP Coating System in very simple English. You will learn about layers, temperature limits, thickness, surface preparation, inspection methods, and where these coatings are used.

What is 3LPE Coating System?

3LPE (Three Layer Polyethylene) is a coating used for protecting steel pipelines from corrosion.

Layers in 3LPE:

FBE (Fusion Bonded Epoxy) – Anti-corrosion layer
Adhesive Layer – Bonds coating layers
PE (Polyethylene) – Outer protective layer

Temperature Limit:

Normal temperature ≤ 80°C

Example:

Underground water pipelines

What is 3LPP Coating System?

3LPP (Three Layer Polypropylene) is used when pipelines operate at higher temperatures.

Layers in 3LPP:

FBE (Fusion Bonded Epoxy)
Adhesive Layer
PP (Polypropylene)

Temperature Limit:

High temperature ≤ 140°C

Example:

Hot oil pipelines

Key Difference: 3 LPE vs 3LPP Coating System

Feature	3LPE	3LPP
Full Form	Three Layer Polyethylene	Three Layer Polypropylene
Outer Layer	PE (Polyethylene)	PP (Polypropylene)
Temperature	≤ 80°C	≤ 140°C
Application	Normal temperature	High temperature
Example	Underground water pipeline	Hot oil pipeline

Coating Thickness & Test Values

FBE: 200–300 µm

Adhesive: 200–300 µm
PE (3LPE): 2.0 – 3.0 mm
PP (3LPP): 2.0 – 3.5 mm
Holiday Test: 5 – 25 kV

Surface Preparation

Before coating, the pipe must be properly cleaned.

Steps:

Remove oil and grease
Shot blasting – SA2.5 or SA3
Achieve clean metal surface

Important Point:

Surface should be very clean for coating to stick properly

Inspection Methods

✅ 1. Surface Cleaning Check

Ensure no dust, oil, or rust

✅ 2. Layer Thickness Check

Check thickness of each layer

✅ 3. Holiday (Spark) Test

Detect pinholes or coating damage

Acceptance Requirements

For coating to be accepted:

Surface must be clean
Coating thickness must match required values
No holidays (pinholes)
Proper bonding between layers

Where These Coatings Are Used

3LPE Used In:

Underground pipelines
Water pipelines
Normal temperature conditions

3LPP Used In:

Hot oil pipelines
High temperature pipelines
Example: Crude oil pipeline (~130°C)

👉 Both coatings are mainly used for external/Internal pipeline protection

Conclusion

Both 3LPE and 3LPP coating systems are used to protect pipelines from corrosion. The main difference is temperature. 3LPE is used for normal temperature pipelines up to 80°C, while 3LPP is used for high temperature pipelines up to 140°C.

3LPE is commonly used for underground water pipelines, while 3LPP is used for hot oil pipelines. Choosing the correct coating is very important for safety and long life of pipelines.

FAQs – 3 LPE vs 3LPP Coating System

1. What is 3LPE coating used for?

It is used for underground and water pipelines at normal temperature.

2. What is 3LPP coating used for?

It is used for high temperature pipelines like hot oil pipelines.

3. What is the temperature limit of 3LPE?

Up to 80°C.

4. What is the temperature limit of 3LPP?

Up to 140°C.

5. What tests are done in coating inspection?

Surface cleaning, thickness check, and holiday (spark) test.

3 LPE vs 3LPP Coating System – Complete Guide for Pipeline Coating