Belt Service factors - High temperatures

Aidan Mitchell
(not verified)
Posted in: , on 9. Mar. 2002 - 05:27

Should an additional service factor be applied when selecting belts for high temperatures? How much and when is it applied?

I have a belt in a hot service (ammonium phosphate) apprx 215 F. The belt has a epdm rubber compound and is performing well. My concern is that the belt (Carcass) is underrated. The belt is in an elevator service so there is no cooling effect as there could be on a conveyor.

Is some literature, including goodyears red book they make reference to an additional envirnomental service factor. In it they suggest applying a .75 factor to the belt rating in order to select the belt.

What effect doe temperature have on the carcass (nynon & poly) and what should I expect to observe?

Any comment or suggestions would be appreciated.

Regards Aidan

Re: Belt Service Factors - High Temperatures

Posted on 11. Mar. 2002 - 05:01

Dear Aidan:

The 215F temperature should not present a problem. Therefore, the 75% safety factor should not apply.

Both polyamide (nylon) and polyester carcass materials can withstand this temperature quite well -- especially with the protection of the EPDM cover.

In high heat conditions, the fabric can embrittle and lose all of its tensile strength. When this happens, each layer of fabric can crack and rupture lines can appear on the belt cover - even if the cover rubber is still good. If transverse cracks appear on the cover rubber, investiate the carcass integrity by probing with a spatula or by removing a section of the cover. If the carcass is brittle, consider a belt change-out before it breaks.


Dave Miller ADM Consulting 10668 Newbury Ave., N.W., Uniontown, Ohio 44685 USA Tel: 001 330 265 5881 FAX: 001 330 494 1704 E-mail:

Belt Safety Factor - Elevated Temperature

Posted on 26. Mar. 2002 - 08:32

Dear Mr. Mitchell

Your assesment is correct regarding splice capacity at elevated temperature. Above 65 deg. C, the belt core rubber physical properties usually begin to lose fatigue strength. Manufacturer's core gum compounds differ as does their performance. We have tested steel cord belts for splice dynamic fatigue at elevated temperatures using a hydr. Instron machine, hot plate radiator, and thermal couples for monitoring. The core gum capacity of some mfgs. dropped over 50% at 120 deg C. The range at this temperature was 50-85%. Some belts were then rejected from consideration for the overland design. The belt was installed and has been in operation since 1999. The belt in this comment transported hot briquettes. The conveyor is 7km long.

Also note, that the power consumption usually will rise at this temperature, thus furthering the need for a stronger belt.

We await any further questions.

Lawrence Nordell


Conveyor Dynamics, Inc.

1111 West Holly St.

Bellingham, WA,

USA 98225

Ph 360/671-2200

Fx 360/671-8450


Lawrence Nordell Conveyor Dynamics, Inc. website, email & phone contacts: phone: USA 360-671-2200 fax: USA 360-671-8450
Geert Seynhaeve
(not verified)

Re: Belt Service Factors - High Temperatures

Posted on 1. Jul. 2002 - 01:24


Have you ever considered to use a steel carcass instead of textile for your high temperature applications ? Steel will not give in at the temperatures mentioned.

Bekaert offers a whole range of woven steelcord fabrics called Fleximat(R). Textile belt manufacturers can easily exchange standard textile materials with this steel reinforcement on their calendar.

The steelcords used have been adapted in order to immitate the elongation of textile while preventing the disadvantage of creep. So no adaptations are needed on your conveyor installation.

Also rubbers are easily adaptable to adhere very well to the brass coated steelcord.

Don't hesitate to drop us a mail if you're interested and will give you a list of belt manufacturers which have used our Fleximat(R) reinforcement.

Kind regards.

Re: Belt Service Factors - High Temperatures

Posted on 1. Aug. 2002 - 10:59


The rubber, not the steel, looses strength at the higher temperatures.


Lawrence Nordell Conveyor Dynamics, Inc. website, email & phone contacts: phone: USA 360-671-2200 fax: USA 360-671-8450

Re: Belt Service Factors - High Temperatures

Posted on 21. Aug. 2002 - 09:52

Hi Aidan !

High temperature up to 215 F° represents no difficulty for the nylon or polyamid carcass but for the splicing. A hot splicing traditionally resists only 70 to 90 % of the nominal strenght of a multiply belt by static resistance tests under normal temperature (68 F°). Dynamic testing with 10.000 impluses up to 25 % of the nominal belt strenght every 50 seconds demonstrate the real strenght under more realistic conditions. After this the splice will usually breaks at only 40 to 60 % of the nominal belt strenght. Under high temperature the final resistance of the splice will be only 20 to 40 %. The splice is your Achille's heel, that why all the belt manufacturers try to overdimensioned their belts.

Have you ever considered to use the new mechanical and elastic splice "Super-Screw", produced by Minet SA in France ? With a textil carcass and a high temperature rubber cover and using self taping screws it represent an interesting alternative and should solve your problems! You will find more information under their web site

Best regards

Edgar Jakob

Managing Director


Uferstr. 2a

94315 Straubing / Germany

Phone: +49-9421-180844

Fax: +49-9421-180893



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