A Guide To The Manufacturing Methods Of FRP Manhole Cover

FRP covers have robust strength to bear heavy loads while adding visual beauty to residential and commercial utility points. So, don't you want to know about the FRP manufacturing process of manhole covers? 🤔 Read with us to know about the step-by-step making process of FRP manhole covers.

20 Dec, 2023
The Complete Guide To FRP Manhole Cover Manufacturing Process - blog poster

FRP Manhole Covers: What Is It?

FRP covers, popularly known as Fibre Reinforced Plastic manhole covers are a strong alternative to traditional manhole covers like cast iron covers, and precast concrete covers. They are made of composite materials like polymer or plastic embedded with fiberglass which results in lightweight yet durable and strong manhole covering lids.

Not only that, fiber-reinforced covers have high resilience to harsh climatic conditions and corrosion. Combing which makes an FRP cover the perfect manhole cover for outdoor usage. 

So, are you looking for the right type of manhole cover for your outdoor sewer setting? 😌

Then, you must check out our FRP covers in Kolkata which come in different customized shapes and sizes. As the top manhole covers manufacturer and paver blocks manufacturers in Kolkata, we can say that the structural properties of FRP covers offer robust benefits while adding visible aesthetics to any underground utility point. 

But, do you know that the FRP manufacturing process involves steps that are different from the making process of other manhole covers?

Well, continue reading this blog to unfold facts about the FRP manufacturing process. 😉

A round shaped FRP manhole cover

Recommended: A Guide To The Gallery Of Features Of FRP Manhole Covers

What Are The Benefits Of Fiber Reinforced Plastic Covers (FRP)?

Before you start understanding the intricacies of the FRP manufacturing process, you must understand in what ways can an FRP cover benefit your outdoor project.

So, let's get started! 🤩

  • FRP manhole covers are the best when it comes to enduring heavy loads and weight. The inherent strength of fiberglass combined with resin reinforcement can not only withstand heavy vehicular weights but is also capable of staying strong under extreme climatic conditions.
  • Unlike traditional manhole covers, FRP composites are lighter in weight. Thus, making it easy for you to install it and remove it for maintenance.
  • FRP materials in manhole covers are durable and have anti-corrosion properties. Thus, making it ideal for places that have high humidity and moisture content in the air.
Aesthetically pleasing FRP manhole cover image

Read Also: Ultimate Advantages Of FRP Manhole Covers By Om Concrete Products

What Are The Raw Materials Needed For FRP Manhole Covers?

Do you know that the weight of an FRP manhole cover is one-seventh of the total weight of a traditional cast iron cover? 🤭

Yes, that's right! The covers of FRP are made from the mixture of the following:

  • Fiberglass - Raw fiber glass strands used in the molding process of the FRP covers make the integral structure of the covers harden to support and bear heavy weights without bending or breaking down.
  • Resin - Unsaturated resin mixture, usually polyester helps in binding the fibreglass reinforced plastic together to give it a desired shape. Thus, making the external surface of the final product strong and durable.
  • Additives - Various additives are incorporated in the fabrication of the FRP manhole covers to enhance the surface finish and strength of the product.

These are the basic raw materials that are needed in the FRP manufacturing process of the manhole covers. So, now let's find out what makes the rigid profile of FRP manhole covers in the manufacturing process step-by-step.

What Are The Steps Of Manufacturing FRP Manhole Covers?

As the world is shifting towards sustainable practices for a healthy eco-space, our FRP manufacturing process also incorporates the values of maintaining sustainability. So that, the world can be a better place. 🌍

Read this step-by-step FRP manufacturing process guide for drain covers to understand, how the FRP manhole products are created.

1. Preparation Of Compression Molding

The first step of the molding process involves the combination of the pull and extrusion process, which is also known as the pultrusion process. It involves meticulously cleaning the moldings to ensure that the final surface veil is smooth and hard enough to withstand weight. 

Henceforth, an application of release agents is applied to the composite materials that make sure that the composite does not get stuck to the molds in the curing process. 

2. Reinforcement Of Glass Fibres

In this process, multiple layers of fiberglass roving are laid strategically to get the desirable length and thickness of the final product. After this, a layer of resin is applied evenly on the fiberglass surface to ensure saturation of the composite materials.

Thus, all this reinforcement passes through the pre-forming creel in a cross-section manner, which ultimately shapes up the final product of the manhole cover.

3. Curing Of FRP Covers

Once the reinforced materials are pulled out of the pultrusion heated die, the next step of thermosetting takes place. Which makes the resin harden to give a rigid shape to the die mold within which all the reinforcement materials are laminated together.

The curing process needs an optimal controlled temperature to maximize the strength of the fiberglass-reinforced materials.

4. Cutting And Trimming Of The Final Product

Once the curing of the reinforced materials is over, the hard materials pass through the saw-cutting process. To give the exact shape required to the composite fiberglass, where excess materials are cut off and trimmed before it get dispatched to the customers.

It also helps to enhance the visual appeal of the FRP manhole covers and ensures a smooth finish for the final FRP products.

5. Quality Inspection

Checking the quality of the product and the process plays a pivotal role in ensuring that the FRP manhole covers meet the desired expectations and guidelines. Inspections are led out at each step while the FRP covers are in the making stage to detect and rectify potential defects.

6. Strength And Durability Testing

As you already know, the main purpose of FRP drain covers is to provide unexceptional strength to withstand heavy vehicular and footfall weights in various commercial and residential infrastructures. 

That is why, tests are carried out on the various samples of the FRP materials to ensure that they are strong enough to serve their purpose. 

A flat FRP drain cover pic

Read More: FRP Manhole Cover Vs Cast Iron Manhole Cover - A Comprehensive Guide 


FRP manhole covers are truly a guide in providing a safe passage to utility access points while covering open drains that resist severe accidents.

You can also check out our range of customizable FRP manhole covers on our website of Om Concrete Products.