Glass Reinforced Plastic (GRP) Pipes: Chemical Resistance and Applications

Introduction

GRP or Glass Reinforced Plastic pipes are in great demand in places where chemical resistance is a requirement because of its anti-corrosive features. It can be used in chemical processing plants, water treatment plants, and even within the industrial piping systems. In the article below, I will study and elaborate on corrosion resistance of GRP pipes, its determinants, and how to choose the material suited for the task.

What is Glass Reinforced Plastic (GRP)?

GRP is an acronym for the plastic and fiberglass composite known to some as fiberglass reinforced polymer (GFRP), or Fiberglass Reinforced Plastic (FRP). A fiberglass composite is formed when operational plastic is reinforced with the integration of microscopic glass fibers. The integration provides a lightweight, durable, and corrosive resistant material useful in diverse fields including piping systems.

Chemical Resistance of Glass Reinforced Plastic pipes (GRP)

Corrosive pipeline plumbing systems are inherently aggressive to the polymer making them suitable for venting pipelines. Their anti-corrosive capabilities are reliant on various determinates:

Resin Type

Different resins provide different levels of resistance:

Polyester Resins – Appropriate for standard multifunctional use with moderate resistance against corrosive chemicals.
Vinyl Ester Resins – Gives additional resistance against acids, alkalis and other solvents.
Epoxy Resins – For costly aggressive chemicals, epoxy gives excellent anti corrosive resistance.

Concentration of Chemicals

The concentration of the chemical transforms the ability of GRP pipes to undergo an attack. GRP pipes may face accelerated degradation with increased concentration.

Operating Temperature

The resistance of chemicals in GRP pipes is affected by high temperature. The long-term durability of specific chemicals is accompanied by temperature limits which should be followed by the manufacturers.

Exposure Duration

Over time, applying aggressive chemicals for long periods can cause GRP pipes to lose their structural integrity.

Choosing Glass Reinforced Plastic pipes (GRP) for Chemical Applications

Appropriate GRP pipes for application are selected with the aid of chemical resistance charts which users are provided by manufacturers. The supplier of resin provides information for chemical resistance claiming:

The material’s upper service temperature limit is verified.
The service life under realistic conditions is established.
Has the material been subjected to ASTM C 581 standard or equal?

Uses of Glass Reinforced Plastic pipes (GRP) in the Chemical Sector

GRP pipes are employed for a variety of chemical transports such as:

A- Hydrochloric acid, up to 37 % concentration, e.g. used in demin units. GRE (epoxy) has limited resistance against hydrochloric acid (< 10 %) and therefore GRVE (vinyl ester) shall be used, lined with a resin rich layer (liner), reinforced with double C-glass veil.
B-Sodium hydroxide (caustic), up to 50 % concentration, e.g. used in chemical plants. Glass-fibre is not resistant against sodium hydroxide, and therefore only “lined” GRE or GRVE shall be used. The resin rich liner shall be reinforced with double synthetic veil (e.g. Nexus), and thickness of the liner shall be minimum 1.5 mm.
C-Sodium hypochlorite solution, e.g. used in chlorination units. Sodium hypochlorite, typically produced on-site using electrolytic cells, i.e. concentrations typically up to 1 %, and pH in the range 9 to 10, will attack all thermoset resins. However, UPVC lined GRVE is a proven option for the transport of sodium hypochlorite.

Benefits of Using Glass Reinforced Plastic pipes (GRP)

Corrosion Resistance- Great reliability for a wide range of aggressive chemicals.
Lightweight- Far more manageable and easier to install than metal pipes.
High Strength-to-Weight Ratio- Cost effective durability without heavy burden weight.
Low Maintenance- Extensive lifespan with little care requirements.
Versatility- Can be customized for different applications.

Comparison of Glass Reinforced Plastic pipes (GRP) with Other Materials

Property	GRP Pipes	Steel Pipes	PVC Pipes
Corrosion Resistance	Excellent	Poor (without coating)	Moderate
Weight	Lightweight	Heavy	Lightweight
Strength	High	Very High	Moderate
Maintenance	Low	High	Low
Cost	Moderate	High	Low

Maintenance and Inspection of GRP Pipes

In order to keep GRP pipes functional, maintenance and review of the pipes is essential:
Visual Inspection- Monitor fractures, delamination, or defect manifestation on the surface.
Chemical Compatibility Testing- Check for any chemical damage from time to time.
Ultrasonic Testing- Examination of the pipe’s thickness and general health.
Pressure Testing- Confirm that there are no leaks and the system is not losing pressure.

Conclusion

For industries dealing with chemical piping, Glass Reinforced Plastic (GRP) pipes are an exceptional prefabricated choice. They are superior durable, lightweight, and have strong resistance to corrosion making them perfect for the transfer of aggressive chemicals. With the right selection of resin to be used in combination with proper supervision, industries can develop effective long-term and efficient piping systems by neglecting damage from chemical substances by proper maintenance systems.

FAQs

Q1: What is the difference GRP vs. FRP pipes? A1: Both GRP (Glass Reinforced Plastic) and FRP (Fiberglass Reinforced Plastic) are frequently being confused with each other, but FRP is a more general label that encompasses all fiber reinforced plastics while GRP applies solely to glass fiber reinforced plastics.

Q2: Are GRP pipes suitable for potable water applications? A2: Yes, if GRP pipes satisfy required health and safety protocols, they can be used for potable water applications.

Q3: What is the shelf life of GRP pipes? A3: When properly used and with regular maintenance, the lifespan of GRP pipes exceeds 50 years.

Q4: Do GRP pipes have UV resistance? A4: Indeed. GRP pipes can be made with UV-resistant coatings to protect them from sunlight damage.

Q5: In what ways are GRP pipes fitted together? A5: Adhesive bonding, butt and wrap joints, and mechanical couplings all different ways of joining GRP pipes depending on the application.