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Redco EXTREN – Answers To Your FAQS

Redco EXTREN – Answers To Your FAQS

Fiberglass reinforced plastic (FRP) composites have been used in a wide variety of industries for decades. But knowledge of the material and its properties are not yet common knowledge, so we’ve assembled some answers to frequently asked questions that come up regarding the material.

1.) What is EXTREN?

This is the most general question but it alludes to the three grades of Redco EXTREN available. EXTREN is a series of plate, tube, and shapes of mechanical-grade FRP and is a made of glass rovings and mat bound by a plastic resin. There are three basic grades available:

EXTREN 500: Polyester resin, non-fire retardant, olive-green in color.

EXTREN 525: Polyester resin, fire retardant, grey in color.

EXTREN 625: Vinyl ester resin, fire retardant, beige in color (for applications with aggressive corrosion concerns)

All three grades have a UV-inhibitor to make the EXTREN suitable for outdoor use.

2.) How much more does EXTREN cost than traditional materials such as steel, aluminum or wood?

This answer can only be made by splitting the question into two parts. The upfront cost of EXTREN is more than all of the comparable materials, perhaps between 2-3 times more, depending on the product. However, the product was never meant to compete with traditional materials on upfront cost.

In many applications EXTREN has a vastly lower lifecycle cost, this is because EXTREN will last much longer before replacement, require much less maintenance, be much easier to install, suffer much less corrosion damage, or any combination of those properties and others not listed here. Frankly, EXTREN would not have persisted as a viable product for so many decades if it did not offer customers substantial advantages and cost-savings over the long term!

3.) What is the operational temperature range of EXTREN?

Series 500-525 EXTREN can handle operational temperatures up to 150 degrees Fahrenheit and the 625 series can handle up to 200 degrees.  All three product lines are excellent in cold applications and can operate down to -60 degrees Fahrenheit.

4.) How long will EXTREN last outside?

This is impossible to say. It depends on location, sun exposure, and weather patterns: there is no way to simply calculate this, nor is the material guaranteed for a specific amount of time. What will occur first is a discoloring of the EXTREN but this does not affect physical strength. If extra UV-protection is desired, polyurethane or epoxy based paints will help.

5.) What is the fire retardancy of EXTREN?

Series 525 and 625 have a 94 V-O flame spread rating. Series 500 is not fire retardant.

6.) What MIL-spec does EXTREN meet?

There are several specs that reference FRP:

MIL R 21607 (GRADE 1, TABLE 1, OR CLASS A) – Series 525 conforms to the flammability requirements of the specification and will certify as such.

MIL R 7575 – The resin Series 500 and Series 525 conform to this specification. The requirement specifies a
polyester resin.
MIL P 25421 (This specification has been superseded by NAVSEA Dwg. 803-5000903 Rev. C) – This is for a glass cloth reinforced epoxy round
tube and cannot be certified. Redco EXTREN can be certified to some of the mechanical properties of this specification, and this has been acceptable to
several of the Naval Shipyards. The product has a special glass orientation; therefore, is a custom, not a shelf
NAVSEA Dwg. 803-5000903, Rev. C (Replaces MIL P 25421) – Is a specification for specially reinforced round
tubes with higher crosswise properties and a higher full section modulus than standard EXTREN. Certifications can be provided. Sizes offered are presently are 1-1/2”, 1-3/4”, 2” and 2-1/2” round tubes with 1/4” wall.
MIL P 17549C, GRADE 3 – This is a specification for flat sheet that EXTREN cannot meet. It does meet the mechanical properties of Table 1, in the lengthwise direction, but not in the crosswise direction; therefore,
it cannot be certified.

If you have further questions about Redco EXTREN or would like additional assistance please contact us.