Secure Connection Soft "Pipe" to Hard Pipe 3

[JavaMoose]

Hello all,
Been a lurker for a while, first post asking for help. I'm working on a project where I need to come up with a secure way to couple LLDPE 20mil tubing to "hard" pipe. Lines will be either 6" or 8" diameter, I'm looking at either HDPE or PVC for the hard lines on the system. System will be filled with Salt Water, low pressure of around .5 bar, fluid will be flowing and not static.
Problem I am running into is how to securely couple the tubing to the pipe. My first though was using stainless hose clamps with a gasket in-between the LLDPE tube and the pipe. However, I'm not sure if this is the most secure (or economical) way to go about this. Just seeing if anyone has any thoughts, ideas or knows of a product that would fit my needs. Any other questions of further clarifications, ask away.
Joe

 

[Jmoore1]

http://technom.test.componence.com/...yloc-Products-Catalog-GLOC-105-12-02-A4-1.pdf

Take a peak at the above link for grayloc connectors, im not sure whether you can get them in plastics or tubing, but Ive used them for connecting two different materials of piping without a bimetallic weld.

 

[JavaMoose]

JMoore, those look like a nice connector - like a grown-up sanitary clamp. However, not seeing how those would work in my set-up. Maybe on the HDPE/PVC side, but not on the LLDPE tubing side.

Just to be clear, the LLDPE tubing has a wall thickness of .508mm - so it is thin and flexible, though it is pretty strong.

 

[jdarco]

Are you injecting something into the line with the tubing? If so, look up "injection quill" and you may find something that will work. Or, why not just drill and tap the PE or PVC pipe, assuming it has enough wall thickness, and use a MPT x Compression fitting like Jaco or Parker?

 

[MikeHalloran]

Yeah, on the LLDPE side, I'd slip it over some rigid pipe or tube. ... after deburring and radiusing the end of the rigid pipe or tube, and adding a bead about 1/4" from the end if possible.

Then I'd secure it with triple hose clamps. ... but I'd isolate the LLDPE from injury by the hose clamps by interposing a layer of thick tough hose. You might be able to find marine exhaust hose in the right size, or wrap the PE with a strip of reinforced rubber sheet.



Mike Halloran
Pembroke Pines, FL, USA

 

[JavaMoose]

Mike: Similar to what I was thinking initially. I really like the idea of welding a bead near the edge of the pipe (maybe even one between the clamps too) - like making a custom barb fitting, in a way.

I wonder about wrapping the LLDPE tubing with the "rubber" sheet though, I guess it would have to be fairly thin. I was looking at higher-quality hose clamps, SUS316L, smooth-band with rolled edges for soft pipe.

I'm wondering, if I went this route, wether or not a gasket would be required in-between the LLDPE and the HDPE (or PVC) pipe?

 

[kacarrol]

I'm not too sure about cost effectiveness or even what size they come in but I used storz connections on a project like this (but the hose was 2 1/2"). There are a couple of other names for couplings here:

http://en.wikipedia.org/wiki/Hose_coupling

This company offers flanged hose spigots and some other couplings in the sizes you require:

http://dixoneurope.co.uk/pages/english/products/water-couplings.php

(see the last few pages of the "King" Combinations Nipple PDF)

I thought I'd just add that as an FYI.

 

[MikeHalloran]

I wouldn't attempt to use sheet gasket.
I'd use RTV silicone, which is removable with some difficulty,
or 3M 5200 Marine Sealant, which is essentially permanent,
and is available in ~3oz tubes at, of all places, Wal-Mart.



Mike Halloran
Pembroke Pines, FL, USA

 

[JavaMoose]

@ Kacarrol: Those Dixon connectors are great! I'm going to contact them and see if they can do 6" or 8" in Nylon or UV stable PP. Since the system is full of seawater I would like to stay away from wetted metals. Thanks!

@ Mike - RTV sounds like a good way to go. I loathe 5200, just personal preference.