Submersible Nylon cable ties

[Chitahua]

I've got an application where I need to install cable ties to support a submersed product . the product weighs about 5.0lbs and will be strapped on a 2" pipe.. I know nylon is hygroscopic, but I've done some testing under hot water for about five weeks with positive results but I'm worried about long term. Given that it's not supporting much weight, does anybody know if it ok. to use Nylon cable ties for this situation?

 

[Pud]

Nylon 12 ties would be a better option (if you can get them where you are in the world)

Nylon 6 and 6.6. do not like chlorides much so avoid salt water, etc.

http://www.tynevalleyplastics.co.uk

Why be happy when you can be normal?

 

[patprimmer]

A lot of nylon rope is used on ships. It is mostly nylons 6 or 6.6. Also many fittings on sailing boats are nylons 6 and 6.6.

Chlorides are certainly an issue in the presence of zinc such as contained in poor quality brass.

I am more concerned about the temperature of the hot water.

Nylon will soften and lose tensile strength with exposure to water due to it being hygroscopic, but it will reach equilibrium with the water and stabilise. As nylon is quite strong even after water absorption, it will depend on the load. To test place a cable tie in hot water (say 80 deg C for say a week, then test strength. By then it will have absorbed all the water it is likely to.

A second issue however is relevant. You mention temperature. Nylons also hydrolyse in hot water given time.

Regards
Pat
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[Chitahua]

Thanks for the feedback.. My test was done with 70°C Water for three weeks. I'm pretty sure it reached maximum water absorption. Although the cable ties (which are Nylon 6/6) became brittle, they easily maintained the necessary strength. The product will not be exposed to those temps very frequently. (about as frequent as you will purge a boiler). However, it will frequently be exposed to brine water. What sort of problems do Chlorides present? will the Nylon react to chlorides and decompose?

 

[patprimmer]

At 70 deg C it will.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

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[bithkits]

How about looking at the rapstrap?

[URL unfurl="true"]http://www.rapstrap.com/[/url]

Not sure if it will be strong enough though. Made from elasticated polyurethane

Adriaan.
I am a Mechatronics Engineer from South Africa.

http://www.martin-electronics.co.za

 

[patprimmer]

Polyurethanes can be quite poor to hydrolysis in water at room temperature. 70deg C sure as hell won't reduce that problem.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

http://eng-tips.com/market.cfm

for site rules

 

[bithkits]

Polyurethanes can be quite poor to hydrolysis in water at room temperature. 70deg C sure as hell won't reduce that problem.

Interesting, thanks!

Mechatronics Engineer from South Africa.

 

[TomDOT]

How about a stainless steel worm-drive (hose) clamp? They are available in a wide variety of sizes, and 304 or 316 stainless.