GRE pipe material properties are the numbers a design engineer needs after the word “GRE” is already on the shortlist: modulus, thermal expansion, hydraulics and the temperature basis the datasheet actually uses. This guide helps operators, EPC teams and procurement engineers turn a published material table into support, anchor, expansion and line-sizing questions — without inventing flows, wall thicknesses or certificate numbers.
GRE (glass-reinforced epoxy) is the epoxy-matrix fiberglass family used for many oilfield line-pipe duties; the definitional contrast with GRP belongs in GRP vs GRE Pipes: What’s the Difference?. Here the job is narrower: use the published IFGS property set for acid-anhydride GRE designed as per API 15HR, and declare the resin and temperature basis before you treat any figure as your design value.
Service-fit selection for high-pressure GRE line pipe belongs in High-Pressure Fiberglass Line Pipe Selection: When API 15HR GRE Fits (Service Envelope, DN, Joints, RFQ). How to write the full GRE/FRP specification from pressure, temperature and medium belongs in How to Spec GRE/FRP Line Pipe from Pressure, Temperature, and Medium. Corrosion drivers stay with their owner page — this post does not rewrite them.
Why design engineers need the material data sheet, not just “GRE”
Calling a line “GRE” only names the matrix family. Anchors, guides, restraint spacing, expansion loops and hydraulic sizing need the published gre pipe material numbers for the resin system you are buying — and a clear statement of the temperature basis those numbers sit on.
CNPS supplies API 15HR certified fiberglass pipe (and API 15LR / 15S / 17J certified products in their families). That statement names the product family; it does not replace the size-specific datasheet or invent certificate or monogram numbers. Request certificate copies in the RFQ when required.
For the catalogue summary that carries the property table used in this guide, start from IFGS intelligent fiber glass solutions Catalog — the primary product page for this post. How to read an API 15HR claim and which evidence to ask for is covered in API 15HR Fiberglass Line Pipe Standard: Reading an API 15HR Claim and the Evidence to Request.
Published IFGS property table (as stated) and what each value is used for
The live IFGS catalogue page publishes a property set for acid-anhydride GRE line pipe designed as per API 15HR. Quote these figures only with that label. They are not a free-standing rating for every resin system or every diameter.
| Property (as published on IFGS) | Published value | Typical design use |
|---|---|---|
| Medium temperature | ≤ 65.5 °C | Upper bound for this anhydride table — not a substitute for your design temperature |
| Density / specific gravity | 1.95 g/cm³ (121.74 lbs/ft³) | Weight take-off, handling and support reactions |
| Heat conductivity | 0.40 W/m·°C (0.23 BTU/ft/hr/°F) | Heat-loss / heat-gain checks; insulation questions |
| Coefficient of linear expansion | 14×10⁻⁶ mm/°C (6.1×10⁻⁵ in/in/°F) | Expansion length, anchors and guides (page unit as published) |
| Hazen-Williams factor C | 150 | Friction method for water-like lines when that method is declared |
| Absolute roughness | 0.0053 mm (0.00021″) | Darcy/Colebrook-style friction when roughness is the method |
| Hoop elastic modulus | 24.1 GPa (3.5×10⁶ psi) | Circumferential stiffness language for pressure containment |
| Axial elastic modulus | 11.9 GPa (1.7×10⁶ psi) | Longitudinal stiffness language for restraint and thermal load paths |
| Poisson ratio (minimum) | 0.38 | Coupling of hoop and axial strain under load (qualitative use here) |
The same IFGS page states production scope DN40–DN900 and pressure rating 3.45 MPa–34.5 MPa, and cites API Spec 15HR-2016 and SY/T 6267-2006. Those scope lines frame the catalogue; they are not a pressure-per-DN table. For the high-pressure product envelope, see High-Pressure Fiberglass Line Pipe and the Oct 23 guide linked above.
Use each published value for the check it belongs to. Do not invent flows, wall thicknesses, pressure-per-DN ratings or certificate numbers from this blog table.
Thermal expansion and conductivity: anchors, guides, expansion questions
Two published numbers drive most early layout questions:
- Linear expansion. The IFGS acid-anhydride table states a coefficient of linear expansion of 14×10⁻⁶ mm/°C (also given as 6.1×10⁻⁵ in/in/°F). Ask the supplier how that coefficient is applied over your installed length, temperature swing and restraint scheme — and whether the expansion calculation sits on the same temperature basis as the property table.
- Heat conductivity. The same table states 0.40 W/m·°C (0.23 BTU/ft/hr/°F). Use it when you are checking heat loss or gain; do not treat it as an insulation specification.
Before you freeze anchors and guides, put these questions into the RFQ (answers are supplier/datasheet items — this guide does not invent them):
- What free thermal growth do you calculate for our length and ΔT on the offered resin system?
- Where must anchors, guides and expansion loops sit relative to tees, flanges and steel tie-ins?
- Does the offered joint system carry axial load, or must guides take it?
- Is the conductivity figure for the pipe wall only, or does it assume a coating or wrap?
Keep expansion qualitative until the datasheet and layout length are on the same sheet.
Hoop vs axial modulus and Poisson: restraint and supports (qualitative)
Filament-wound GRE is anisotropic. The IFGS acid-anhydride table states a hoop elastic modulus of 24.1 GPa and an axial elastic modulus of 11.9 GPa, with a Poisson ratio (minimum) of 0.38.
In plain language for support and restraint conversations:
- Hoop modulus speaks to circumferential stiffness under internal pressure. It is part of why GRE line pipe is discussed for pressure containment in its class — it is not a substitute for the rated pressure of your diameter.
- Axial modulus speaks to longitudinal stiffness. Thermal growth, buried restraint and guided runs load the pipe axially; the axial figure is the language of those conversations.
- Poisson (minimum) 0.38 couples hoop and axial strain. Treat it as a reminder that a restrained GRE line does not behave like isotropic steel; ask the manufacturer how they want restraint modelled for the offered construction.
Support spacing, anchor loads and burial factors belong in the manufacturer calculation for the offered size and joint system — not in invented blog formulas.
Hydraulics: Hazen-Williams C and roughness (method, no invented flows)
The IFGS acid-anhydride table publishes two hydraulic surface figures:
- Hazen-Williams factor C = 150
- Absolute roughness 0.0053 mm (0.00021″)
Use them as method inputs when your project standard says which method applies:
- If the hydraulic basis is Hazen-Williams, declare C = 150 as the published GRE figure for this table and keep the calculation on your flowsheet — this guide does not invent flow rates, velocities or head-loss results.
- If the basis is Darcy/Colebrook (or equivalent), declare absolute roughness 0.0053 mm and run the friction factor on your own Reynolds numbers.
Do not mix methods silently. State the method in the RFQ so every offer uses the same surface figure for the same duty. Density 1.95 g/cm³ from the same table supports weight and handling take-offs; it is not a hydraulic friction input.
Temperature basis depends on resin system (declare yours)
The IFGS acid-anhydride GRE table is published against medium temperature ≤ 65.5 °C. Other CNPS fiberglass line-pipe pages use different temperature wording for different constructions:
- High-pressure fiberglass line pipe (PDP 9411) states temperature resistance up to 110 °C.
- The combined API 15HR / 15LR FRP pipeline page uses the wording API-rate 93 °C–110 °C.
- The API 5B thread GRE pipe page states a design-temperature basis of 93 °C for wall thickness and also carries 110 °C maximum-operating language on the same page — resolve by declaration, not by averaging.
Resin system decides the temperature basis. Acid-anhydride GRE numbers on IFGS are not automatically valid at a 110 °C headline from another page. In the RFQ, declare:
- your design fluid temperature and any short-term excursion;
- the resin / cure system you are buying (anhydride vs other);
- the temperature basis you want every property and rating to sit on;
- that offers must not mix a 65.5 °C anhydride table with a different page’s 93/110 °C wording without saying so.
Until that declaration is written, treat every published temperature figure as page-specific evidence.
Data to request with a GRE line-pipe quotation
Put material data on the same sheet as pressure, DN and joints. A minimum set:
| RFQ field | What to write |
|---|---|
| Standard / edition | API Spec 15HR-2016 (and SY/T 6267-2006 if required) — or the edition your project names |
| Size / pressure class | DN and class language; confirm inside published DN40–DN900 and 3.45–34.5 MPa family scope where that scope applies |
| Resin / cure system | Acid-anhydride or other — named, not assumed |
| Temperature basis | Design T + the datasheet basis (do not mix 65.5 °C anhydride with 93/110 °C page wording) |
| Material table | Confirm hoop / axial modulus, Poisson, expansion, conductivity, density, C and roughness against the offered construction |
| Expansion / restraint | Anchors, guides, loops; who calculates free growth for your length and ΔT |
| Hydraulics method | Hazen-Williams C and/or absolute roughness — method named |
| Joints / fittings | Joint family and any flange or fitting interface (owned elsewhere; declare here) |
| Documents | Size-specific datasheet, IFGS catalogue reference, certificate copies if required |
For a broader EPC package layout, see What EPC Buyers Should Put in an FRP/GRE Pipe RFQ Package. When the material fields above are filled, send the sheet through Talk to an Engineer so the offer is built against your temperature basis and resin system — not a generic “GRE” headline.
FAQ
What are GRE pipe material properties in this guide?
They are the published IFGS figures for acid-anhydride GRE designed as per API 15HR — density, conductivity, linear expansion, Hazen-Williams C, absolute roughness, hoop and axial moduli and Poisson (minimum) — used for design checks, not for service selection or a full GRE definition.
What is GRE pipe material versus GRP?
GRE is glass-reinforced epoxy; GRP is the broader glass-reinforced plastic family. One definitional line is enough here — use the GRP vs GRE contrast linked in the lead for the full contrast.
Why is the IFGS medium temperature ≤ 65.5 °C when other pages say 110 °C?
Because temperature basis follows resin system and page scope. The IFGS acid-anhydride table is published at ≤ 65.5 °C; other CNPS pages state up to 110 °C or 93–110 °C wording for other constructions. Declare your design temperature and the datasheet basis in the RFQ; do not flatten the figures.
Can I use Hazen-Williams C = 150 for every fluid?
C = 150 is the published IFGS acid-anhydride figure. Use it when your project standard applies Hazen-Williams. For other methods, use the published absolute roughness 0.0053 mm. This guide does not invent flow rates or head-loss results.
What do hoop and axial modulus mean for supports?
Hoop modulus (24.1 GPa as published) speaks to circumferential stiffness; axial modulus (11.9 GPa as published) speaks to longitudinal stiffness under thermal and restraint loads. Support spacing and anchor loads still come from the manufacturer calculation for the offered size — not from blog formulas.
Where is the primary product page for these numbers?
The IFGS catalogue product page linked once above as the primary CTA. Pair it with the high-pressure line-pipe page and the Oct 23 selection guide when the question is service fit rather than material data.
What is the fastest next step?
Confirm the IFGS acid-anhydride property set against your resin and temperature basis, fill the data-request table, and send it through Talk to an Engineer with your DN, pressure class and joint family declared.
