3PE Coated Steel Pipe

3PE Coated Steel Pipe (Three-Layer Polyethylene)

1. Introduction

3PE coated steel pipe is widely used for buried oil, gas, water transmission and infrastructure pipeline projects where long-term corrosion protection and mechanical resistance are required. The 3PE coating system is typically designed according to project specifications such as DIN 30670 and ISO 21809-1, combining a fusion bonded epoxy layer, an adhesive layer and an outer polyethylene layer.This three-layer structure provides strong adhesion to the steel pipe surface, improved resistance to soil stress, moisture exposure, impact and abrasion during transportation, handling and installation. For pipeline projects in regions such as Africa and the Middle East, buyers should confirm the coating standard, coating thickness, cut-back length, holiday test requirements, pipe end preparation and inspection documents before production.

For buried or exposed pipeline sections, the coating decision is not only about corrosion resistance; buyers also need to check coating thickness, holiday testing, end cutback and protection during loading.

Forever Steel supplies 3PE coated steel pipe, also known as 3LPE coated pipe, for buried oil, gas, water transmission, sewage and underground pipeline projects. The three-layer polyethylene coating system normally includes an epoxy primer, adhesive layer and polyethylene outer layer to improve corrosion resistance and mechanical protection.

2. 3PE and 3LPE Coating Structure

A 3PE coated steel pipe is built with three external anti-corrosion layers over the steel pipe substrate. The first layer is a high-performance FBE primer, which bonds directly to the blasted steel surface and provides corrosion resistance. The second layer is a grafted copolymer adhesive, which connects the epoxy primer with the polyethylene outer layer. The third layer is a tough HDPE top coat, which protects the pipe against soil stress, impact, abrasion and handling damage during buried pipeline service.

3. 3PE Coated Steel Pipe Applications

Application	Why 3PE / 3LPE Is Used	Buyer Should Confirm
Buried gas pipelines	Polyethylene outer layer improves mechanical protection	DIN 30670 or ISO 21809-1 class
Crude oil pipelines	Corrosion protection for long-distance buried service	Pipe grade, coating thickness, cutback
Underground water transmission	Protects pipe from soil corrosion and handling damage	Holiday test and coating repair rule
Sewage systems	External protection for buried wet environments	Base pipe type and coating standard
Piling or infrastructure pipe	Extra protection during soil contact and installation	Impact risk, packing and loading method

4. 3PE Coating Structure and Quotation Checklist

Layer / Item	Function	RFQ Requirement
Epoxy primer	Bonds to blasted steel and provides corrosion resistance	Primer type and minimum thickness
Adhesive layer	Connects epoxy primer with PE outer layer	Compatible adhesive material
Polyethylene outer layer	Mechanical protection against soil and handling damage	Total coating thickness and coating class
Base pipe	Seamless, ERW, LSAW or SSAW pipe	Standard, grade, OD, wall thickness
Pipe ends	Welding and field joint preparation	Cutback length and bevel protection
Inspection	Confirms coating continuity and thickness	Holiday test, DFT report, visual inspection

5.3PE Coated Pipe Inspection Before Shipment

Before shipment, Forever Steel can check coating thickness, surface appearance, holiday test results, cutback length, pipe marking, bevel protection, packing condition and required mill test certificates. For large-diameter 3LPE pipe, loading control matters because coating scratches, edge damage and impact marks can create problems before installation.

Coating Technical Data for Finished 3PE Coated Pipes

Test Property	Unit	Requirement (Standard)	Test Method
Peel Strength (Adhesion)	N/cm	≥100 (at 20°C) / ≥40 (at 50°C)	DIN 30670
Impact Resistance	J/mm	≥7	DIN 30670
Indentation Resistance	mm	≤0.2 (at 23°C) / ≤0.3 (at 50°C)	DIN 30670
Elongation at Break	%	≥600	ASTM D638
Cathodic Disbondment	mm	≤7 (at 65°C, 24h)	ASTM G42
Holiday Detection	kV	25 kV (No breakdown)	ASTM G62
Surface Resistivity	Ω	≥1012	DIN 30670

Overview of 3PE Anti-corrosion Steel Pipe Technology Details

Parameter	Technical Detail / Requirement
Applicable Pipe Types	Seamless (SMLS), LSAW, SSAW, ERW
Diameter Range	88.9 mm – 2020 mm (Standard range)
Standard References	DIN 30670, CAN/CSA-Z245.21, ISO 21809-1, NF A49-710
Coating Thickness	Generally 2.0 mm to 3.7 mm (Depending on pipe diameter and project requirements)
Service Temperature	-40°C to +80°C
Surface Preparation	Sa 2.5 (Near-White Metal Blast Cleaning) as per ISO 8501-1
Anchor Profile	50 μm – 100 μm (Roughness for optimal FBE adhesion)

DIN 30670 Coating Thickness Requirements for 3PE Coated Steel Pipe

Nominal Diameter (DN)mm	Outside Diameter (OD)mm	Type N (Normal) Class	Type S (Special) Class
		Min. Thickness (mm)	Min. Thickness (mm)
≤ DN 100	≤ 114.3	1.8	2.5
DN 100 < DN ≤ 250	114.3 < OD ≤ 273.1	2	2.7
DN 250 < DN ≤ 500	273.1 < OD ≤ 508.0	2.2	2.9
DN 500 < DN ≤ 800	508.0 < OD ≤ 813.0	2.5	3.2
> DN 800	> 813.0	3	3.7

Minimum 3LPE Layer Thickness Range

Mkg/m	3LPE Layer thickness(mm)
	Class A1	Class A2	Class A3	Class B1	Class B2		Class B3	Class C1	Class C2	Class C3
M≤15	18	21	26	13	18		23	13	17	21
15	20	24	30	15	21		27	15	19	24
50	24	28	35	18	25		31	18	23	28
130 300	2,6	3,2	3,9	2,2	2,8		3,5	2,2	2,5	3,2
300	32	38	47	25	33		42	25	30	38
Please note:The total required thickness may be reduced for SAW pipes by a maximum of 10%on joint seam. Class 1 and 2 for medium and light applications (sandy soil). Class 3-application in extreme conditions(rocky soil)or underwater.

Minimum Finished Coating Thickness for 3LPE Coated Pipes

Steel Pipe Sizes						Min Coating Thickness in mm
≤103/4”(273.1 mm)						2.5
>123/4”(323.9 mm)to≤18”(457 mm)						2.8
>20"(508.0 mm)to≤30"(762 mm)						3.0
>32"(813.0 mm)						3.3

3PE Coating Process for Steel Pipes

Frequently Asked Questions

1. How do you verify coating quality on 3LPE coated steel pipe before shipment?

We implement internal quality control from raw material review to final shipment release. For orders related to buried gas pipelines, crude oil lines, and underground water transmission, buyers usually expect the product to match both the application and the supporting 3LPE coated steel pipe, DIN 30670, ISO 21809-1, and API 5L base pipe requirements.

2. Can you provide holiday test records, MTC, and third-party inspection for 3LPE pipe?

Yes. We can provide Mill Test Certificates according to EN 10204 3.1, and 3.2 can be arranged when required. Third-party inspection by agencies such as SGS, BV, or ABS can also be accepted before shipment.

3. How do you prevent coating scratches on 3LPE pipe during inland transport and ocean freight?

We use export-oriented packing and loading methods based on the product type, including end protection, stable bundling or blocking, waterproof wrapping where needed, and careful loading control. The goal is to reduce rust, scratches, bevel damage, face damage, coating damage, thread damage, or handling impact during domestic transport and long sea shipment.

4. Is 3LPE coated steel pipe normally used for buried gas and underground water pipeline projects?

This product is commonly supplied for buried gas pipelines, crude oil lines, and underground water transmission, with buyer demand often tied to 3LPE coated steel pipe, DIN 30670, ISO 21809-1, and API 5L base pipe.