NATURAL GAS PIPE LINES.........PITTED AREA SAFTY

[myapples]

WHAT ARE THE MEASURES AND WAYS TO MAKE PITTED AREA/SPOTS ON PIPES TO MAKE IT SAFE TO AVOID LEAKS AND OTHER HAZORDS,AND HOW PITTING ACCURES WHILE PIPES ARE LYING OUTSIDE THE GROUND(EARTH),AND HOW IT STARTS IN THE GROUND.

 

[Metalguy]

Grind the pits out and measure remaining wall thickness--must be above minimum--don't forget corrosion allowance too.

Wet storage, differential oxygen conditions, and carbon steel will pit unless something is done to prevent it--like coating, etc.

Don't allow pipes to sit on ground. As a minimum, put thick layer of gravel (for drainage) under them.

"You see, wire telegraph is like a very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? Radio operates the same way: You send signals here, they receive them there. The only difference is there is no cat." A. Einstein

 

[SJones]

Consult the PRCI Pipeline Repair Manual

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04

 

[brimmer]

To measure the corrosion you can use a pit gauge or pencil probe with UT flaw detector. Once corrosion is mapped, complete fitness for service evaluation (B31G, RStreng, API 579 etc.). Many repair options available, sleeves are commonly used on gas pipelines for external corrosion.
As far as how the corrosion accures, or occurs, the iron in the pipe (Fe) is reacting with oxygen in water to produce iron oxides/hydroxides, but this is a very simple explanation, you can easily look this up in any corrosion book and background info. I highly recommend you seek outside help from consulting company in the area of NDT to map corrosion& pipeline integrity to complete fitness for service and repair options to assist.

 

[awol]

Fastest and cleanest method to repair local pitted pipe is a composite repair. Minimal training to install. Mostly designed for short section of pipe. Not intended for full stick lengths. Many suppliers to choose from.