Coatings Corner - Experts in Action
Gas Flow Efficiency and Epoxy Resin Based Coatings
Pranav Purani
Improving Gas Flow Efficiency
Worldwide demand for gas pipeline capacity is at historic highs and expected to rise, with an expenditure of more than US $200 billion over the next 20 years. Sustaining while increasing flow efficiency — through:
- Improving capacity
- Fighting corrosion
- Reducing and controlling pumping costs is key to meeting gas delivery projections.
Flow efficiency coatings, now a major established technology, are a sensible, effective means of helping ensure current and future demand is met. Such coatings are created by a thin film (80-130 microns thick when dry) applied internally to pipe, mainly to reduce friction between the gas and the roughness of the internal steel surface.
One of the most reliable and commonly used types of coating is epoxy resin based. With the establishment of global standards - the most common being API RP 5L2 and ISO 1574 - pipelines can be assured that epoxy resin based coatings meet or exceed quality specifications in such areas as:
- Adhesion
- Porosity
- Flexibility
- Chemical resistance
- Corrosion resistance
- Hardness
- Resistance to pressure variation
Using epoxy based resins achieves significant positive consequences, both onshore and offshore:
- Helps optimize the number of required compressor stations.
- Contributes to meeting product purity.
- Reduces valve maintenance.
- Allows greater flexibility for product switchover.
- Reduces the energy cost of pumping.
- Provides corrosion protection while pipes are in storage or transit.
- Supports the effectiveness of pigging and scraping.
For pipeline owners, contractors, and coaters, these advantages can translate into:
- Lower project capital cost
- Reduced commissioning costs
- Speedy inspection Faster pay-back
Application of Epoxy Based Resin Coatings
The coatings' two components - resin, known as the "base" and the curing agent, known as the "hardener" or "activator" - both of which come in liquid form, are mixed wither before or during application. No heating is necessary.
Products mixed during application generally use plural component spray equipment. Proper manufacturer specified mix ratio is set on the proportioner. Appropriate manufacturer specified spray nozzle, orifice size, and spray pressure are selected.
The spray nozzle is mounted on the end of the spray boom, which moves from one end of the pipe to the other while the pipe rotates on a rig.
To achieve the desired uniform wet flow thickness of 200-220 microns, adjustments are made to the following:
- Speed of the spray boom
- Rotation of the pipe
- Distance between spray tip and pipe surface
- Pressure of spray
Coating curing results from cross-linking and polymerization.
This Coatings Corner was produced from a full article by the author that ran in World Pipelines. You may reach Mr. Pranav Purani at pranavpurani@berryplastics.com to discuss how flow efficiency epoxy resin based coatings can make a difference in your capacity.