GRP Pipe Standards for Engineers – Design, Pressure Classes, Global Codes (2025)

GRP pipe or glass reinforced plastic pipe is a fundamental material in construction. Due to its high corrosion resistance and strength-to-weight ratio, it is used in agriculture, water systems and marine industry. Worldwide, there are several major standards for pipelines which GRP pipe follows. Whether nationally or internationally, they shape the world in a way to boost the similarity between all manufacturers.

GRP pipes standards guarantee the quality, safety, and function of glass-reinforced plastic pipes which should apply for water, sewerage, and chemical systems. Standards like ISO 10639 or AS 3571 define material essential properties (resin and glass fiber), manufacturing and jointing methods, testing, and installation. Additionally, they require marking and labels which lasts over decades and ease tracking and identifying.

In this article we’ll figure out what exactly these standards are and how they affect the quality and manufacturing process of GRP pipe.

Overview of Global GRP Pipe Standards

GRP pipe standards, not only go through each step of GRP pipe’s production to make sure of consistency in pipe’s properties, but also, they follow installation and pipe performance in various environments. Let’s break it into both national and international standards:

North America

In North America, there are three central standards for GRP pipe which include quality, water utility, and chemical resistance.

1. ASTM Standards (D2996, D3517, D3754): ASTM D2996, D3517, and D3754 show the specifications of GRP pipes for design engineers and QC inspectors. ASTM D2996 is for filament-wound pipe corrosion resistance used in industrial purposes, while ASTM D3517 requires several tests for pressure endurance and hoop strength in water and wastewater systems. As noted in ASTM International, the following ASTM D3754 pipes are perfect for buried applications or sewage systems to focus on a long lifespan while being eco-friendly.
2. ASME B31.1 / B31.3: ASME B31.1 and B31.3 are two other pipe standards which are essential in industrial application of GRP pipes such as food and beverage or off-shore and on-shore piping. According to ASME, ASME B31.1 code will provide power plants to control their temperature and pressure conditions via using GRP pipes. Also, ASME B31.3 checks for the right joints in chemical and petroleum industries where integrity and corrosion resistance are desired.
3. AWWA C950: In pipeline standards for water systems, AWWA 950 shines as a leader to persuade design engineers for portable water pipelines. AWWA 950 takes control of joints systems, manufacturing process, and after installation testing to avoid leaks in water systems. For American specialists who are looking for long-term investments via resistant and long-lasting pipelines, AWWA considers a wide range of standardizations. (source: Academia-edu)

Europe

BS 5480, BS 7159, EN 14364, and DIN 53769 Series of European standards go through pipelines’ standards to guide engineers achieve the best match for their demands.

1. BS 5480: As a key pipe standard in the UK, BS 5480 plays such a role in above-ground and buried pipelines. Due to measuring and controlling the nominal size (DN) and pressure (normally up to 25 bar), this may insist on chemical resistance and leak proofing.
2. BS 7159: In the UK infrastructure designs, BS 7159 assists engineers to select the perfect material and installation method for high-pressure applications like water and industrial systems or high-temperature aims such as chemical pipelines.
3. EN 14364: As mentioned in Afnor EDITIONS, EN 14364 indicates the right properties for joints and installation of GRP pipes based on toughness, diameter size, and pressure resistance.

1. DIN 53769 Series: The DIN 53769 series refer to German grp pipes which include tests for hydrostatic pressure tolerance and fittings. These series are mainly used in chemical, water, and wastewater systems to ensure pipes will handle high pressures (to 40 bar).

International standards (ISO)

ISO standards shape the construction of pipe’s performance, utilities, installation and fundamental properties in a way to create such a stable base for water supply, industrial and marine applications.

1. ISO 10639: engineers keep seeking a reliable pipeline’s standard for buried installation or irrigation. Whether in a high-pressure or a non-pressure water utility, ISO 10639 specialize GRP pipe characteristics as diameter size, joints systems, or durability via standard tests.
2. ISO 10466: ISO 10466 evaluates how pipes perform in water and drainage systems without getting any degradation in aggressive environments and external loads. The standard emphasizes the long lifespan of pipes to develop infrastructure for large-scale projects.
3. ISO 10471: ISO 10471 essentially tests ring deflections or pipe behavior in harsh situations. It has assisted manufacturers in preventing mechanical troubles or deformation for decades. These properties made ISO 10471 a global choice for experts.
4. ISO/TR 10465-1/2/3

After all, ISO/TR 10465-1/2/3 go through guiding engineers who are  looking for their international projects’ demands. It includes three central parts:

Part 1: Checking installation methods

Part 2: Going through static calculations methods

Part 3: Testing parameters, limitations, and functions of pipe for an ideal buried system.

Australia

Australian GRP pipe standards normally rely on material properties and installation conditions, while fulfilling local criteria.

1. AS 3571: As Australia’s national GRP pipe standard, AS 3571 is followed by pressure tests (diameter size and wall tolerance). According to STANDARDS Australia AS 3571 has two versions: AS 3571.1 (2009) covers sewerage and drainage pipes, while AS 3571.2 (2009) evaluates the properties of water supply pipes, supporting sizes from DN 100 to DN 2500 and pressures up to 25 bar.
2. WSAA Appraisals: WSAA refers to the Water Services Association of Australia which is used for water and sewer systems. These types of appraisals will assure you with evaluation of size (DN 100 to DN 3000) and pressure resistance (up to PN 35).

GRP Pipe material standards

GRP pipes are such an amalgam of a magnificent trio, including a resin matrix, glass fibers, and other aggregates or additives. These raw materials are also followed by several standards.

Here, we’re providing an explanation of both ISO and ASTM with a comparison table for better understanding:

Resin Specifications

Based on ISO 10639, the resin matrix of GRP should be selected between unsaturated polyester (UP) or vinyl-ester (VE) to resist pressure and non-pressure water.

As mentioned in ASTM D3517, thermosetting polyester or epoxy resins are allowed to be used to reach the desired pressure resistance while showing the flexible and durable components.

Glass Fiber Specifications

E-glass (alumino-borosilicate glass) is required due to its high strength (≥2,400 MPa) and corrosive-resistant properties. Check ISO out for more information.

According to ASTM D3517, E-glass fibers, including filament diameters of 6–24 µm are the best match for creating a consistent pipe base.

Aggregate Specifications

Fillers like siliceous sand (ISO 10639:2017) or mandates siliceous sand (ASTM D3517-19) are mainly used to improve the reinforcement and stiffness of structural aims.

Component	ISO 10639:2017	ASTM D3517-19
Resin	UP or VE, chemical resistance	Polyester/Epoxy, ≥2% elongation
Glass Fiber	E-glass, ≥2,400 MPa tensile	E-glass, 6–24 µm filaments
Aggregates	Optional, siliceous sand	Siliceous sand, 30–50% filler

Laminate Structure Requirements

GRP pipes are covered by structural and inner layers or such optional outer layers followed by standards like BS EN 14364 and ISO 10639.

Liner Design: Based on BS EN 14364 covers the inner side with a resin liner for corrosion avoidance, while ISO 10639 provides thermoplastics or thermosetting resin liners to resist internal pressures in water supply or portable water systems.

Structural Layer Design: The structural layer like glass fiber-reinforced will assist pipes through high stiffness classes up to SN 5000 by following BS EN, while ISO 10639 contains filament-wound layer to reach high strength.

Outer Layer Design: These outer liners are covering the pipes to avoid UV or mechanical damage in above-ground pipelines.

GRP Manufacturing Method Standards

There are several methods for manufacturing the GRP pipes, such as centrifugal casting or filament winding. Each may follow such unique standards:

Filament Winding

At this process filament-wound reinforced thermosetting resin pressure pipes (RTRP) up to 24 inches in diameter are created regarding ASTM D2996 standards.

The process is all about roving glass fibers with resin base to shape a multi-layered pipe by rotation onto a mandrel.

Centrifugal Casting

Reinforced polymer mortar pipes (RPMP) are mainly used in sewer systems and industrial applications are evaluated through ASTM D3754 standards.

To form a dense and smooth inner layer of pipe the centrifugal casting shows how resin, glass and aggregates are rotating in a mold. Learn more on What is GRP Pipe.

Dimensional and Mechanical Classifications

GRP pipes are categorized by pressure (PN) and stiffness (SN) to contain various applications’ aims.

PN (Pressure Classes): Classifying classes such as PN 1 (no pressure) PN 4, PN 6, PN 10, …, etc. these classes provide the maximum available pressure in the bar to reach internal pressure resistance of each in water systems.

SN (Stiffness Ratings): Clarifies stiffness classes such as SN 2500, SN 5000, and SN 10000 (measured in N/m²) to indicate the resistance-rate of the external side of pipe under high-pressure buried applications.

Wall Thickness and Performance Tables

Wall thickness is a critical parameter related to pipe size, pressure rating, and stiffness class.

Wall thickness: It can define the minimum wall thickness based on diameter size (DN 50 to DN 4000), stiffness rates, and pressure classes (PN) to improve structural cohesion under both internal and external pressures.

Performance Tables: Manufacturers provide such a comparative table to indicate how they are related and sink to the standards. Some tests like hydrostatic pressure (ASTM D2992) and ring stiffness (ISO 7685) are required to measure these properties. Here is a sample wall thickness table:

DN (mm)	PN	SN	Wall Thickness (mm)
300	PN 16	SN 5000	10–15
600	PN 10	SN 10000	15–20

Jointing Standards

Joints ensure leak-tightness and structural integrity in GRP piping systems via standards like ISO 8639 and EN 1092 on different joint methods.

EPDM Couplings: In this type of joints, ISO 8639 lightens the way of leak proofing via tests under conditions like internal pressure, bending, or extensions to assure the joints are flexible and rubber-sealed.

 Flanged Joints: For metal or GRP rigid rings that support leakproofing under high-pressure water systems, standards like BS 4504 contain pressure rates in circular flanges, while EN 1092 goes through PN-rated GRP pipes.

Feature	EPDM Couplings	Flanged Joints
Flexibility	High (allows movement)	Rigid (fixed connection)
Pressure Handling	Moderate	High (depends on flange class)
Installation	Quick (rubber-sealed)	Requires bolting & gaskets
Standards	ISO 8639	EN 1092, ANSI B16.5, BS 4504

Testing Standards

Testing will aid manufacturers in reaching the safety and flawless performance they desire across various conditions. Below, we’re providing you with key standards:

ASTM D3567: It will define dimension measurement of GRP pipes through parameters such as outer and inner diameter, wall thickness, and longevity. It also includes tapered dimensions to assist engineers in selection.

ISO 8521 and ISO 8513: ISO 8521 test wall thickness via six methods (using burst method as the reference method) which goes with all pipe’s sizes, while ISO 8513 by using strip or a cross-section method to test strength under specific loads like during installation process.

ISO 7685, ISO 10471, ISO 10468: These standards check pipes for long-term deflection or ring creep properties under wet conditions over decades through constant load or deflection methods.

ASTM D2992: going through cyclic or static pressure testing to determine the safety of GRP pipes under high-pressure water systems for both reinforced thermosetting resin pipes (RTRP) and polymer mortar pipes (RPMP).

ASTM D4161: defines the flexibility of seal joints through checking for leaks under pressure and deflections, while covering pipes in different lengths to flow water easily in water systems.

Certifications of GRP Pipes

Certifications define manufacturing quality with regional requirements, providing assurance to stakeholders.

ISO 9001 certifies an intact quality management system to continue consistency during the production process of GRP pipes, while ISO 14001 is focused on environmental conditions and sustainable trends to prove their responsibility toward nature.

AS 3571.1 and AS 3571.2 cover drainage, water supply, and sewerage systems. These standards follow ISO standards to indicate the material and design of pipes for local infrastructures.

WSAA appraisals which are managed by Water Services Association of Australia to ensure all GRP pipes are qualified in their perfect criteria (long lifespan and water utility authorities) in water and sewer applications.

Installation Standards

ISO/TR 10465-1/2/3 set standards for buried installation and backfill to avoid any damage. Comparing static calculations and defining installation parameters, in addition to including safety factors and aggressive soils, will make such a perfect installation and durable pipe over decades.

Product Marking Requirements

Clear marking by following the GRP pipe standards is required to identify and trace pipes easily. As noted in ISO 10639 each pipe’s mark should contain several factors in durable labels to track them over the years:

• Manufacturer’s name or logo
• Product type (for example, GRP-UP is for unsaturated polyester)
• Nominal size (DN, like DN 300)
• Pressure rating (PN, such as PN 16)
• Stiffness class (SN, for example, SN 5000)
• Batch number

Conclusion

Finally, we’ve got to the last part. GRP pipes standards shape the way of unique pipelines all around the world through their strict rules. From global standards of GRP pipes to standards of each component of them such as material, installation, manufacturing methods, or jointing, we’ve clarified each by a comprehensive explanation. Overall, standards will provide us with a wide range of certifications to guide this industrial and durable line!

FAQs

1.How does ISO 10639 contribute to GRP pipe standards for water systems?

Whether in a high-pressure or a non-pressure water utility, ISO 10639 specializes in GRP pipe characteristics such as diameter size, joints systems, or durability via standard tests

2.What countries support GRP pipes standards globally?!

There are multiple countries that set standards for GRP pipes through various testing. North America, UK, Germany, and Australia provide manufacturers with a wide range of standards to meet their demands.

3.How do GRP pipe standards ensure proper installation?

ISO/TR 10465-1/2/3 set standards for buried installation and backfill to avoid any damage. Comparing static calculations and defining installation parameters, in addition to including safety factors and soil conditions will make such a perfect installation and durable pipe over decades.