Gilsonite in Pipe Coating: An Overview
Buried steel pipelines carrying water, oil and gas must be protected from corrosion for decades. Bituminous coatings — including those modified with gilsonite — have a long record in this field.
Why pipes corrode
Moisture, oxygen and soil salts attack bare steel. Coatings act as a barrier and work with cathodic protection.
Role of gilsonite
- Raises hardness and softening point of bituminous enamels
- Improves adhesion to steel
- Reduces cold flow and sagging
- Increases resistance to soil stress
Coating types
- Hot-applied bitumen enamels
- Cold-applied primers and mastics
- Coating tapes with bituminous adhesive
Main bituminous pipe coating systems
| System | Application | Typical use |
|---|---|---|
| Hot-applied enamel with glass fibre | Coating plant or field | Water and oil pipelines |
| Cold-applied tape | Field | Repairs, fittings, small pipes |
| Mastic | Brush or trowel | Valves, bends, irregular shapes |
| Bituminous paint | Brush or spray | Ductile iron and concrete pipes |
Why gilsonite is added
Pipe coatings must resist soil stress (movement of soil around the pipe), impact during laying and flow at elevated service temperatures. Gilsonite raises softening point and hardness while keeping adhesion to steel.
Where bituminous systems are used today
Many new oil and gas pipelines use polyethylene or epoxy systems, but bituminous coatings remain common for water pipelines, rehabilitation, field joints and repairs because they are economical and forgiving to apply.
See pipe coating grade gilsonite and bitumen enamel pipe coating.
Recommended product
Coating & Waterproofing Grade Gilsonite
| Property | Typical value | Test method |
|---|---|---|
| Appearance | Black powder | Visual |
| Softening point (R&B) | 150 – 200 °C | ASTM D36 |
| Ash content, max | 5 % | ASTM D3174 |
| Moisture, max | 1 % | ASTM D95 |
| Solubility in TCE, min | 97 % | ASTM D2042 |
| Particle size | ≤ 200 mesh | Sieve |
| Typical dosage | 5 – 25 % of compound | |
| Packing | 25 kg bags palletized; 1 MT jumbo bags. | |
Typical values. The final specification is confirmed in the COA of each shipment.
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