Re: The LPG problem in Launcer/receiver

From: <elie>
Date: Sat Jul 28 2007 - 18:22:00 EDT

1. You should have 2-pig passage indicators, one 1-km before the trap (warning), and one downstream of the pig trap receiver's isolation valve so you will know the pig is inside the receiver.
2. I suggest renting or leasing temporary tank(s) for capturing LPG. You should not release any flammable liquid into the atmosphere.
3. In order to release nitrogen into the atmosphere, you need Oxygen monitoring instruments to warn personnel of Oxygen deficiency in the surrounding air. Nitrogen may replace the air (Oxygen) and people may die.

   Cheers,

sanjib basu <basusan2000@yahoo.com> wrote:

           Dear Piping Designers/Pipeliners,

The excellent clarity of advise on Pig launcher/ receiver Gordon Rededek again reissued by Paul makes me sit up and feel that probably i could get real help & advise on the problem below:

I have a LPG Pipeline 6" x 30 Km which is to be pigged while commissioning.

The Procedure what is to be adopted may be:

1.Pig the line dry after Hydrotest with HD Foam pig till the foam is touch dry. 2. Introduce Nitrogen Slug between two pigs with say 30% volume/length of the pipeline
3.Introduce LPG ( pressure available 21 BarG) behind the second Pig 4.Blow out the air & Nitrogen by opening two block valves installed back to back by crack opening First & then fully open second procedure.. out of Receiver connected to a separate Vent line erected at a safe distance & height. 5. When Liquid LPG comes in behind the Second Pig --- What should I do?

Supposing I discharge some in atmosphere & close the valves by following the reverse procedure and Close the mainline valve at the receiver, how do I remove the liquid in the Scrapper Trap?

Drain it? Where? how? Safely?

The Client wants to do a baseline survey with LPG and hopes to do it say at an interval of 4 years to asses Corrosion/ pitting if any. At that time the scrapper on either side will be full with Liquid LPG... how do we safely dispose it.

Any one who worked in the Operation please advise. I will have further questions to ask about venting too from TRV's.

Sanjib Basu

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Received on Sat Jul 28 18:22:00 2007