Three-layer polypropylene coating with project-defined thickness and pipe-end cutbacks
Our 3LPP supply combines the specified steel pipe with an FBE primer, adhesive and polypropylene outer layer. Pipeline purchasers can retain the coating class, total thickness, end cutback and release tests as one coating package. The base-pipe grade and wall remain separate, fully identified purchase requirements.
| System | Fusion-bonded epoxy primer, adhesive and polypropylene outer layer |
|---|---|
| Base pipe | Specified steel grade, route, OD, wall and length |
| Coating reference | ISO 21809-1 or the project-adopted PP coating specification |
| Thickness | Selected coating class and purchaser-defined minimum total build |
| End preparation | Coating cutback, edge profile, bare-end protection and weld-end detail |
| Release scope | Approved application procedure and agreed coating inspection records |
Identify the pipe mass per meter before selecting a thickness class.
| Pipe mass Pm (kg/m) | C1 total min. (mm) | C2 total min. (mm) | C3 total min. (mm) |
|---|---|---|---|
| Pm ≤ 15 | 1.3 | 1.7 | 2.1 |
| Over 15 to 50 | 1.5 | 1.9 | 2.4 |
| Over 50 to 130 | 1.8 | 2.3 | 2.8 |
| Over 130 to 300 | 2.2 | 2.5 | 3.2 |
| Pm > 300 | 2.5 | 3.0 | 3.8 |
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ISO 21809-1:2018 Table 2 Class C reference, expressed as minimum total coating thickness in millimeters. The standard permits a 10% total-thickness reduction at SAW weld seams. Each coating order states the adopted edition, project amendments, coating class and required service conditions. The middle mass bands exclude their lower limit and include their upper limit.
The outer layer is PP in 3LPP and PE in 3LPE. A specified PP system keeps its own material qualification and service envelope; replacing the outer polymer is a change of coating system.
The approved application procedure combines surface preparation, material selection, application settings and inspection. Its qualification records identify the coating line, application method and material combination covered by the tests.
The steel specification and required pipe testing are established before coating. Coating acceptance and steel-pipe acceptance remain separate records, joined by the pipe identity.
Bare steel at each end provides the space needed for the joint preparation and field welding. Cutback length and tolerance follow the field-joint system and project drawing.
The transition from coated body to bare end affects how the field-joint coating overlaps. The edge shape and any feathering requirement belong in the coating procedure.
Field-joint material is selected for adhesion to the prepared pipe and adjacent PP coating under the approved installation conditions. The joint specification identifies the compatible material system, preparation and application procedure.
Transport restraints, supports and laying method affect mechanical damage to the coating. Abrasion-resistant additions, concrete overcoating or installation-specific protection are distinct project scopes.
A project pipe list can be matched with its coating schedule and field-joint details. We keep differences in pipe mass, thickness class and end preparation visible instead of assigning one coating build to every size.
Crossings and other mechanically demanding sections may need a different thickness class or additional protection. The installation design defines those requirements alongside the basic corrosion coating.
Inspection records the required total build and its distribution around the pipe, including the weld seam where applicable. Pipe identity links the readings to the released coating lot.
The agreed holiday test checks coating continuity using the applicable procedure and settings. Test voltage is selected for the adopted specification and thickness.
Peel adhesion, impact, indentation and other required tests address different coating properties. Their methods, temperatures and acceptance criteria follow the approved inspection plan.
Cutback geometry, exposed steel preservation and repaired areas are checked before release. A repair retains its qualified material and acceptance record.
Suitable pads and lifting arrangements protect the coating from sharp contact. Bundle restraints and stacking supports avoid concentrating handling loads at a coating edge.
The exposed cutbacks and weld ends receive the specified temporary protection. End caps protect the bore without hiding the need to inspect the coating transition.
Our quote identifies the base pipe, coating system, selected thickness class, cutback, inspection and destination terms. Field-joint materials or additional installation protection are separate inclusions when required.
No. 3LPP uses polypropylene and 3LPE uses polyethylene as the outer layer. Their qualified material systems and service envelopes are separate.
The purchaser selects the class using the adopted specification, pipe mass and installation conditions. The Class C table provides a standard reference; the project requirements establish the actual purchase minimum.
No. Thickness and material qualification address different requirements. The selected FBE, adhesive and PP combination must be qualified for the specified temperature and duty.
The bare cutback allows end preparation, welding and field-joint installation. Its length and edge profile need to match the field-joint procedure and project detail.
No. Holiday detection checks discontinuities. Adhesion is evaluated by its own test method, alongside other required system properties in the inspection plan.
Yes, within the specified base-pipe and coating scope. Weld-seam profile, pipe identity and the applicable seam-thickness allowance remain part of the procedure and acceptance requirements.
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Attach the base-pipe schedule and coating specification, including class, total thickness, design and handling temperatures, cutbacks and required tests. Add quantity and destination. We return the defined steel-pipe, coating and release-document scope together.