Sewer line aerial crossing

[marthab]

Is there a way to insulate a sanitary sewer pipe for an aerial crossing? The pipe is DIP, 8".

 

[bimr]

You would probably want to use 2" frp insulation with a plastic cover over it. Depending on where you are, you would put a self limiting electrical heat tape under the insulation for freeze protection.

 

[rconner]

Ductile iron pipe is "pre-insulated" for many applications (also including hydronic services etc.), with various insulations and jackets applied in somewhat controlled Shop circumstances by many applicators. It is probably also at times field-insulated for various reasons by mechanical contractors etc. I believe pre-insulated pipe vendors in the USA include Thermacor, Perma-Pipe, Urecon and probably others. You could find out more about insulation and other design aspects of such specialty systems with a search involving such words/firms, and/or also talking with contractors, Engineers, Owners etc. experienced in such pipes/systems. I would only add that if there can be low/no flow in the exposed line during periods of extreme cold, it might also be good practice to equip the crossing with a means of draining (of course prior to/in the event of such flow stoppages) and/or with a means (e.g. heat tape etc. talked about by Mr. Bimr) to proactively prevent the contents from freezing.

 

[SlideRuleEra]

Perhaps you could refer to ANSI/AWWA 600, "Installation of Ductile-Iron Water Mains and Their Appurtenances"

http://www.techstreet.com/cgi-bin/detail?product_id=1258385

http://www.SlideRuleEra.net

 

[rconner]

While I would in general recommend C600 as a very good standard that has provided a lot of practical information on a lot of subjects to a lot of folks for some decades, "Piping requiring insulation" is among a short list of specific, specialized issues listed under the heading "Conditions not discussed" in the introductory section of this standard. The standard goes on further to explain that these as a group these are: "Installations that require special attention, techniques, and materials .... Each of these installations requires special considerations based on many influencing factors that cannot be discussed adequately in a single standard. These installations may require design by a competent engineer and consultation with representatives of the material manufacturing industry."
There is however some basic information concerning the structural design and support etc. of uninsulated ductile iron pipe on supports and bridge crossings available from DIPRA at dipra.org (and also some in AWWA Manual M41 (Manual of Water Supply Practices Ductile Iron Pipe and Fittings).

 

[LCruiser]

Where is it, how long is the exposed length, etc.??

 

[bimr]

Here is a standard specification that may answer some of your questions:

http://www.ci.bend.or.us/depts/public_works/docs/6_Division_III_Sewer__lt_green.pdf

The normal insulation for an application like you describe is a fiberglass insulation 2" thick. The fiberglass insulation is protected with jacketing. The jacketing is either plastic, aluminum, or stainless steel. Stainless straps are used to hold the jacketing on.

What you have to consider is the design temperature, and possible exposure to road salt (damage to jacketing).

http://www.pacificinsulation.com/pacins_pages/pipe_insulation.html

http://www.dipra.org/pdf/bridgeCrossings.pdf

http://www.owenscorning.com/comminsul/systems.asp?System=83