Monitoring of Pipe Coating HDD 5

[frank2121]

Dear Mates,

I need to know which methods can be used to Monitoring of Pipeline Coating During Pulling Operation in a Horizontal Directional Drilling (HDD).

How I can know if there is some damage in coating or not ?

Thank you in advance

 

[LittleInch]

As far as I know you can't monitor this.

Most people use at least a 3 layer PE or PP coating, lots of drilling mud and hope for the best.

You can add extra layers like rock guard or pull in a PE liner first then your main pipe and make sure your CP is quite good. This is if you know you're drilling through rocks or sharp gravel.

But even if you find damage what can you do? It's not going to come out again.

A bit more background would help.

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

 

[TugboatEng]

Would a capacitance test after install be applicable here?

https://www.google.com/url?sa=t&sou...Vaw23cdijFHBhio9Ifhxy_XD9&cshid=1626015693984

 

[frank2121]

i dont know if the insulation resistance test can be done after HDD to check the integrety of coating and if there some damage.

 

[TugboatEng]

If one were able to install reference electrodes alone the exterior of the pipe prior to installation a reduction in capacitance could indicate damage to the coating.

 

[LittleInch]

But it's pointless.

You somehow find a test that shows you have some coating damage or maybe a long scratch.

Then what?

There's simply nothing you can do.

All you can do is assume maybe 5 or 10% coating loss and size your CP transformer accordingly.

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

 

[TugboatEng]

Excellent point!

 

[HTURKAK]

If the subsurface is hard abrasive rock , coating loss may occur during HDD installations. In this case, armour coating should be applied..
The following excerpts from ASCE Horizontal Directional Drilling Design Guideline Task Committee ( Eric R. Skonberg,...)

(4.8 STEEL PIPE CORROSION COATING
Steel pipe is subject to corrosion and is therefore generally installed with an external corrosion coating. External coatings used in HDD installations should be well bonded to the pipe to resist soil stresses and have a smooth hard surface to reduce friction and maintain the corrosion barrier (Directional Crossing Contractors Association 1995 ). Numerous external coating products are currently on the market, some designed specifi cally for HDD installations. Mill-applied thin fi lm fusionbonded
epoxy is commonly recommended in a minimum thickness of 20 mils (Directional Crossing Contractors Association 1995 ).

(4.8.2 Armoring Coatings
Coating loss due to abrasion from soil and very soft rock (i.e., shale and mudstone) is not a critical problem in HDD installations unless large, abundant inclusions of signifi cantly harder material are likely to be encountered (i.e., cobbles and boulders). Coating loss occurs during HDD installations through hard abrasive rock (i.e., granite, quartzite, and hard sandstone). In general, bedrock with high unconfi ned compressive strength and Mohs hardness can be expected to be abrasive and cause
coating wear. Point loads from sharp rock fragments and gravel may also gouge coating. Using an armoring coating, or abrasion-resistant overlay (ARO), over the corrosion coating can help preserve the integrity of the corrosion coating and minimize damage that can potentially occur as a result of HDD installation. The length and type of rock to be penetrated should be taken into consideration when specifying the armoring coating (Hair 2002 ). Generally speaking, an armoring coating of 40 mils provides
adequate protection for most subsurface conditions. ARO applications exceeding 40 mils are possible, but the designer should consult the coating manufacturer to assess the risk of the coating cracking during pipe installation....)

I will suggest you to look also, “ Coating requirements for pipelines installed by horizontal directional drilling ( by Hair , J. D. )