Pig Receiver/Launcher related terms 3

[zacharialamsyah]

I rarely involved in Pig Launcher/Receiver design.. Once I Involved i found terms such as "barred tee" , "end closures" and "Kicker line".

What i want to know what the definitions of them?,

Is there Kicker line have same meaning as "bypass line"?
Is there Barred tee have same meanins as "pig trap"?

Thank you for opinions and comments
regards
ZA

 

[zdas04]

Starting at the pipeline you have:
[ul]
[li]Barred tee: A standard tee with pigging bars welded into the branch.[/li]
[li]Side Valve: Connects to the branch on the barred tee, it is the normal path for flow from the upstream through the barred tee, and out to the downstream pipeline while not in pigging mode. In pigging mode the side valve is shut and the flow is through the kicker/bypass through the barrel, reducer, throat, barrel isolation valve, barred tee and out.[/li]
[li]Barrel Isolation valve: Full bore valve between the barred tee and the pig trap.[/li]
[li]Pig Signal (Pig sig): A device to demonstrate when a pig has passed a point. For a launcher it is on the pipeline side of the barred tee. For a receiver it is on the pig trap side of the barrel isolation valve[/li]
[li]Throat: A section of the pig trap that is the same diameter as the pipeline.[/li]
[li]Eccentric reducer: The transition (flat side down) piece from the throat to the barrel on the pig trap[/li]
[li]Barrel: Section of the pig trap that is used to allow a pig to lose velocity on a receiver and to allow some space for loading the pig on a launcher (Typically one pipe size bigger than the throat)[/li]
[li]Kicker Line/Bypass Line: A reduced size line going from the barrel to the side of the side valve not connected to the barred tee. On a launcher it is called the Kicker. On a receiver it is called the bypass.[/li]
[li]Closure: Quick opening fitting on the pig trap to allow access for launching/receiving pigs[/li]
[li]Pig trap: General term for the device between (inclusive) the barred tee, the side valve, and the closure.[/li]
[/ul]

David Simpson, PE
MuleShoe Engineering

Law is the common force organized to act as an obstacle of injustice Frédéric Bastiat

 

[zacharialamsyah]

Thank you david simpson

Your explanation was more than I expected. Informative

Regards
Zachari Alamsyah

 

[LittleInch]

whilst I hate to get into a debate on this too much and the explanation given by zdas04 is very good, often the valve and line quoted above as the "side valve" is termed the bypass valve / line as it "bypasses" the pig trap itself. The kicker line is the one coming from the trap to the far side of the bypass valve and is often referred to as that for both launcher and receiver, though there is a more common trend now to simply have pig traps capable of either duty and not specific to one or the other.

Typically you tend to see two pipe sizes bigger than the main line for the barrel size.

also try and avoid sloping the pig trap - Does very little and just gets in the way. Make the barrel flat.

See attached typical P & ID which has everything you possibly need. Whether you need double isolation is up to you depending on your isolation philosophy and pipeline engineers vary in their designs on this point.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[zdas04]

Dang that has a LOT of expensive valves. Many of them I've never seen
[ul]
[li]Balancing line: I've seen it on drawings, but never in real life[/li]
[li]Actuated valves surrounding the barred tee (never seen either, let alone both. I have seen actuators on the barrel isolation valve, and seen the side valve tied into the ESD system, but never those two valves)[/li]
[li]Check valve on side: I don't know why you'd even want that[/li]
[li]Check valve on the purge connector turns a useful vent into a worthless connection (I put a vent there in case I get a small amount of leak by on the barrel isolation valve you can still launch a pig)[/li]
[li]Taking the PSV to flare is a dangerous waste of time (that PSV is usually sized for thermal relief, mL/min capacity)[/li]
[li]PSV on side valve: I've seen them rarely, but I don't know what code would require them[/li]
[li]Two drains is redundant, I don't even put one drain on a launcher and I have no idea why you'd ever put a spectacle blind on the drain lines.[/li]
[/ul]

You can't stop people from calling things whatever they want to call them. My approach has always been to call things by their proper name and if someone calls a "side valve" a "bypass" or the "bypass valve" on a receiver a "kicker" I just ignore their mistake and use the right name next time I speak.


David Simpson, PE
MuleShoe Engineering

Law is the common force organized to act as an obstacle of injustice Frédéric Bastiat

 

[LittleInch]

I thought it would generate a response... This was an example only but had the bypass / kicker line designation as I normally have them

Balancing lines I design in and have seen them.
The SDV actuated is possibly a step too far, but I've seen plenty of ESD valves in that location. As the bypass valve (side valve) is often the operational isolation valve then it is commonly actuated, sometimes with the infamous "inching facility"
check valve I agree with you - not normally required
Purge connector NRVs- pretty common
PSV to flare - also is the primary vent down line For a fully liquid system would normally go to the closed drain system
PSV on bypass/side line - I agree
Two drains - I've seen two, especially on longer, larger traps just to get the flow working. If you have a liquid line and no drain, how do you open the door to insert a pig without getting your feet wet??
Bypass to me bypasses the pig trap so seems very logical. Side valve could be anywhere really.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[zacharialamsyah]

Other related terms:

Major barrel: An enlarged section of the barrel used for loading or retrieving pigs
Reducer: A between major and minor barrel
Minor barrel: A section of the barrel between the pig trap valve and the reducer.

 

[zdas04]

I've always thought the "minor barrel" and "major barrel" were awkward terminology. Several references that I have call them the "throat" and "barrel", and that seems easier to me. All that really matters is consistency and communication.

David Simpson, PE
MuleShoe Engineering

Law is the common force organized to act as an obstacle of injustice Frédéric Bastiat

 

[RUBABU_imported]

Can anyone share tips on the design of closure door interlock mechanism. If the Pig Launcher / Receiver isolation valve is open, then barrel drain valve should be kept closed during normal pigging operation. But during special pigging operations like pigging with a batch of water and air, then Pig L/R isolation valve and barrel drain valve both needs to be kept open. In this having the interlock mechanism is a problem. I wonder if interlock mechanism should be dismantled during specialised pigging.

 

[LittleInch]

It would be interesting to see what exactly you mean by "specialised pigging" as sweeping out water with air sounds like normal pigging to me... what I suspect is that your downstream system can't handle the water so you're trying to use the pig trap like a separator - water at the bottom flowing out of the drain and gas / air over the top going out the kicker line?? Therein lies your problem - you're trying to use one piece of equipment (a pig trap) as though it is another (a separator). Unless you can advise otherwise this is bad engineering and poor operation and can easily lead to pressurised air in the drain system. Deal with the problem (water and air mixed together) and not the symptom (interlock issues.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[zdas04]

I pulled some of this into a Rules of Thumb document that is a bit dated, but still kind of useful. For closures it says the closure should:
[ul]
[li]Have a pressure telltale as an integral part of the seal mechanism[/li]
[li]Be supported by hinges or davits that would prevent the closure from becoming a projectile in an open-under-pressure situation[/li]
[li]Be able to release pressure while still captured[/li]
[/ul]

This list is why I never specify Huber closures (since they fail on the first and last criteria) and always call for a Y-Yoke closure like the Tube Turns Y-Yoke closure, since the telltale is built into the locking mechanism and the outer seal ring releases pressure before the door can swing free.

David Simpson, PE
MuleShoe Engineering

In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. —Galileo Galilei, Italian Physicist

 

[LittleInch]

Zdas04, They look like good closures, but if you look at the latest question, he's talking about having the main pig trap isolation valves and the drain valve open at the same time(!) There are some very odd end closures out there alright, many scare the living daylights out of me ,a bit like this latest idea of dismantling safety equipment because it doesn't fit your perceived mode of operating....

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[RUBABU_imported]

taking a pipeline for maintenanace, pigging with a batch of water and air/N2 is done to remove hydrocarbon content

 

[LittleInch]

Verbabu,

I understand what pigging involves, what you haven't said is why you apparently want to operate with the main pig trap inlet valve open and the drain valve open at the same time?? Your downstream system should be able to accept water and air if you're doing this sort of operation, not messing about with drains on a pig trap. Diverting to a slops tank is quite common.

Is this liquid H/C??

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[RUBABU_imported]

The barrel drain connection is being used to hook up water from portable tank for injecting water into the pipeline, hence the situation of drain valve & barrel isolation valve both being kept open.

 

[LittleInch]

Ok, now it's a bit clearer. Usually though you use a spare connection on the top of the trap or take off a pressure guage and use that instead. Is there no other connection you couldn't use?

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way