Gravel Bedding for 900mm Diameter Steel Pipe

[harmsgundam]

Hi to all,

I would like to ask if one can use gravel as bedding for a 900mm diameter steel pipe. If yes, what will be the size limit for the gravel to be used? Can you guys site any reference standards or documents to prove this usage? Thank you for those who can answer.

 

[cvg]

you have not given many details so the answer is fairly generic. contractors like pea gravel because it is very cheap, but sand is usually better. I typically avoid gravel. However, there may be some good reason for the gravel that you could elaborate on.

 

[bimr]

It is acceptable to use gravel with steel pipe.

"For many installations, gravel or dry coarse sand falls into place at adequate density without additional compaction."

 

[cvg]

yes, gravel compacts easily, but fine soil can migrate into the voids of open graded gravel potentially causing settlement of the trench. this can be mitigated with a filter layer or with compacted trench plugs.

"Trench Breaker ‐ Trench breakers (also known as trench plugs) are barriers placed within an open
pipeline excavation in order to slow flow and reduce erosion in the trench and also to prevent the trench from becoming a subsurface drainage path."

http://www.elibrary.dep.state.pa.us/dsweb/Get/Rendition-757909/html/index344010.png

 

[harmsgundam]

Any reference standards or documents to prove the usage of gravel as bedding for steel pipes having this diameter of 900mm?

 

[cvg]

google it, there are plenty
without further information, hard to tell what kind of pipeline you are building

 

[LittleInch]

If this is a coated pipeline t provide protection from corrosion, then no, "gravel" is generally too sharp and pressure and any movement can damage the coating leading to corrosion of the steel.

Also depends on the amount of gravel and if the pipe moves in any way. Pea gravel moves under pressure and can allow the pipe to float through it. Sometimes you want some flexibility - most times you don't....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[chocobo1198]

LittleInch is right. For a coated steel pipeline, you want to make sure that the bedding material does not damage the coating. I work for a regional water utility and most of our pipelines now are coated with Lifelast Durashield 310... back then it would be coal-tar enamel. And so... our standard is to backfill with sand. It works well for installation if compacted properly. There is a downside though... when someone has to dig close to it... the sand will just start gushing out... at least in an area where rain is frequent.