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I don't know too much and didn't read all the responses, but I did pick up on the word "steep". I recall a story about the closing of a penstock with a valve unfortunately located at the top of the hill. All the momentum and gravity pulled a vacuum on the line which promptly collapsed.

fvincent, Thanks for your reply. There may indeed be a problem with their measurement or calculations. This is my suspicion bolstered by your response. Actually d/D = 0.163, so a/A = 2.7%. Does this change your response? I'm interested and would be greatly pleased to understand how you...

Thanks you guys!

In other words a circular tube lying bottom center of a circular pipe through which gas is flowing. We've had an entity performing some actual tests for us using air, but we can't believe the results. The capacity loss associated with an area reduction due to the innerduct of less than 3%, is...

Can't find anywhere. Does anyone have typical values for MDPE-MDPE, MDPE-HDPE and HDPE-HDPE. Application is cable being pulled through conduit. Static? Dynamic? Variation with speed? Thanks!

I have a 1/2" stopcock on the branch of a gas service line carrying fiber-optic cable. It is in the vicinity og the gas service line stopcock. Since the only time it should be used is in an emergency by fire or gas utility personnel, and will sever the cable, I'd like to make access...

Hacksaw; Thank you for your reply. The conduit is certified gas pipe. It is installed inside a larger diameter pipeline that operates with gas pressure up to 60 psig. The conduit will only see pressure internally if there is a failure that breaches it. My primary interest is containing the...

Anyone have experience and/or suggestions on how to seal around FO cable exiting a conduit. Sheath of cable and conduit are both polyethylene. Can't access ends. Must be able to contain 100 psig of gas in conduit. Thanks!!!!

Goosen I'm interested in knowing of the references you found that would help calculate/estimate capacity loss of gas flow through a pipe into which a smaller pipe (d/D < .25) is inserted. In other words annular flow outside of innerpipe. Thanks!

We are developing technology for installing fiber optic cable in live natural gas distribution main. I would appreciate your advice. Polyethylene tubing is used as innerduct in the main. It lies straight and in the center at the bottom of the pipeline that is carrying gas at 60 psig. At...

Try Mueller

Let me clarify. Assume the innerduct lies on the bottom of the main and traverses directly over the tap hole. Assume impact on the capacity of the main from innerduct is already accounted for. Question is what is impact on flow out the tap hole due to blockage by innerduct. Assume innerduct...

A natural gas pipeline at around 60 psig contains a tubular innerduct. At certain points the innerduct traverses a tap hole in the main for a branch. Diameter of main/innerduct is from 2-3&quot;/.25&quot;, 4&quot;/1/2&quot;, 6+&quot;/1&quot;. How could I determine the impact of blockage by...

OK, I took a shot at it. I come up with a maximum bend radius of almost 18&quot;, more than double the bend radius of the pipe at its outside wall. If anyone is interested and kind enough to either confirm or suggest a different answer, i would be grateful. Thanks!

I'm using Polyethylene tubing as innerduct in a gas pipe. The internal pressure of innerduct is 0 psig. Would the minimum bend radius specified for innerduct assumed to be used to contain internal pressure still apply, or could a smaller bend radius be used without compromising integrity...

You may wish to refer to gas quality specifications in gas company contracts that address CO2 primarily to limit corrosion I suppose. Pipeline pressure, steel composition, and trace gas constituents such as oxygen, hydrogen and sulfur may also be important factors.

Should be fun for hard-core math types. An innerduct of outside diameter d, runs inside a 4&quot; IPS pipe (0.188&quot; wall). Said pipe makes a 90 degree turn. The elbow used is a long radius, i.e. bend radius of 1.5R or 6&quot;. What is the maximum bend radius in inches of the innerduct...

zdas04. In the case of plastic innerduct and main, the assumption is probably not that much of a &quot;stretch&quot;. Yeah, I imagine your applications are pretty complex. You seem capable of meeting the challenge. Thanks for your helpful responses. Kevin

Thanks zdas04. Our limited flow tests also produced results that were quite a departure from those predicted using the standard hydraulic diameter. We'll give your approach a shot and see if we can close the gap. By the way, do you use this same diameter to calculate friction factor? Some...

Glue the fitting on eh? Intrigueing. I like it! A contact name would be appreciated. Thanks SSC