Wood Lagging for Pipeline Protection 1

[Lumberman]

The use of Wood Lagging in Pipeline construction is an effective and inexpensive way to provide superior mechanical protection during installation, lowering-in and burial; where rocky material would damage the corrosion protection. The wood lagging is manufactured with 11 ga. soft steel wire and stapled to the wood 2x4's to effect a "blanket" which is wrapped around the pipe (wire to the outside)and then strapped tight. Do the staples and wire serve as "sacrificial" anodes or create cathodic risk to the coated pipe?

thanks for your opinions

 

[Metalguy]

Sounds like they are electrically insulated from the pipe, so there should be no effect. Does the pipe have CP to protect any coating/wrapping defects?

 

[Lumberman]

Thanks. Yes. The pipe has CP. The owners query the presence of metal in the vacinity of the pipe. (albeit the soft, low grade metal of wire and staples, vs. Coated and CP Gas Pipe that is 6" to 36" in diameter)

I agree that the separation by the wood is the insulator, and suggest that the wire and staples MAY also assist as sacrifial anodes. Corrosion is always a natural concern.

IF the wood rots over time, and there is "some" gradual slow contact to the coated pipe in places by the ends of the staples, for example (say 10-15 yrs...) will this cause major corrosion problems? Or will the normal periodic monitoring of CP levels neutralize the risk? I'm not a corrosion expert and I'm attemping to get a rationale to agree or disagree with the concerns that have been expressed. Again: Thanks

 

[Metalguy]

The CP should protect any spots where the staples or other things (termites?!) damage the coating. I think you're in good shape if the CP system is well designed and installed.

The staples and wire won't add any protection, but they shouldn't hurt it either.