Vent and drain

[TengkuSyahdilan]

Hello everyone, is there any rule of thumbs about the clearance of one vent pipe or drain pipe to another in liquid pipeline system? How far we must put one vent pipe or drain to another one?

 

[BigInch]

Where are these pipes, in a building wall, in a building floor, buried underground, in contact with soil, above ground, in a pipe rack, what diameter, what are they carrying, what is the pipe material, are they insulated, what code?

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"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[TengkuSyahdilan]

This pipe is aboveground for high speed diesel distribution with material A106 grade B size 6 inch, no insulation and the code is ASME B.31.4.

 

[BigInch]

B31.4 requires 12" clearance to foreign objects when piping is placed underground, or for pipe installed offshore. There is no required clearance for onshore above ground pipe, but it is customary to design to the same 12" clearance, unless there is some very good reason that it cannot be done in specific cases.

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"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[TengkuSyahdilan]

Do you mean the distance from one vent pipe or drain pipe to another vent or drain on aboveground piping is 12 inch?

 

[BigInch]

Yes the clear distance between them. The distance from the edge of a B31.4 pipe to the edge of any other "thing" ... that is not specifically supporting that pipe. I would make exceptions for an instrument mounted on a pipe, a valve operator, instrument air tubing tie-wrapped onto the pipe, etc.

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[TengkuSyahdilan]

Thanks 4 your help Big inch, but i mean by vent pipes here are pipe that Mounted on Main piping or pipeline that use for throw the air out (vent) or use to drain the fluid (drain). Usually liquid pipeline need vent at the higher point of pipe, and drain at the lower point of pipe. My question is how far does the distance between one vent to another vent, or vent to drain. Someone said to me it is usually 5 meter for each vent to another. Is it right? Is there any rule of thumb for it?

 

[BigInch]

What purpose will the vents and drains have? Is it for construction purposes to vent air and drain hydrotest water only, or some other purpose?

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[LUDPEKA1]

Are you asking, if I have a 1,000 foot pipe line, what should be the horizontal spacing between vents and/or drains be?

 

[insult2injury]

If your high point and low point is 5 meters apart, then 5 meters is the correct answer; if they are 10 meters apart, then 10 meters is your answer. Is there something I'm not understanding?

I2I

 

[BigInch]

It could be that there are several local high and low points that need to be vented and drained in a segment of pipeline where there are still yet higher and lower points. Until we know the answer to the purpose of the drains and vents, nobody understands.

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[TengkuSyahdilan]

The purpose are for hydrostatic test and used during operation, cause i thnk when a lines or tanks cools the pressure drop and can cause syphoning or prevent drain beside that when the pressure rise in storage tank (in my case) due to an increase in temperature, it is necessary to release the excess pressure or air. So i need to put vent at high point and drain at low point of pipeline. In this case let we assume i have 1,000 ft of pipeline (like Ludpeka1 said before) so what should be the horizontal spacing between vent and/or drain?

 

[BigInch]

If its a diesel line, you won't have any air to worry about. Hydrotest drains and vents are temporary and should be installed as required based on the location of the test segments and BY the test contractor. Are you the test contractor? Tanks will have their own psv installed ON THE TANK. You do not need to worry about venting tank pressure in your distribution lines. Product lines should be kept full and under slight positive pressure even when not in use.

I don't believe you need any vents or drains in the line, but, I have certainly not seen your PFDs. I just highly doubt it. Near metering or sampling or in various segments of the plant near pumps, for FREQUENT maintenance purposes you might want to install drains running to a closed hydrocarbon-oily water drain system. You may also need small temperature expansion PSVs in segments of the line that can be blocked and exposed to fire or other high temperatures to run to those drains. Those should be located only at low points. Vents may be needed at pig launchers and some other locations where air must be removed from the launching barrel, or where segments of pipe must be removed frequently for operation purposes, not for infrequent maintenance.

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[LUDPEKA1]

I can’t quote any codes and I’ve never run any 1,000’ level pipe lines. I’ve never called out for multiple vents or drains in a long section of horizontal piping. On occasion the project manager or someone from the “field” has requested to install a 1” or 1 1/2” drain in place of the normal 3/4" to speedup the draining process after the hydro.

I don’t how the vent and drain points have any relationship with potential thermal expansion. The tank should be designed with the proper venting system that applies and if the piping system in question has the potential to be blocked in and over pressured a thermal relief valve and piping system needs to be developed. In my experience, this should be developed by a process engineer.

 

[LUDPEKA1]

What BigInch said

 

[TengkuSyahdilan]

Thanks big inch 4 ur valuable input. Unfortunatelly we are also the test contractor here. It is my client that asked to install this vent n drain. They have their own reason. One year ago one of their flexible joint at one of their service line size 3 inch that connect to 8 inch main inlet have been damaged seriously including pipe support near it that go out from the track. It is because of one mistake, when they closed the globe valve on relief valve line that mounted on 8 inch main inlet near tank nozzle, the pressure go back, pass the 8 inch flexible joint and go throug the 8 inch x 3 inch tee and hit the smallest flexible joint. So now they want to put vent before the tee and at any point that seem unsafe. But once again thank for ur valuable input, i'll thnk of it n talk to the client.

 

[BigInch]

A vent won't help that. Anytime its closed, they would still be subject to the same conditions that caused the original damage. Its more than likely caused by water hammer effects from closing that valve too fast. I would guess that the velocity in that line is too high and probably needs to be slowed down.

Locate your 3/4" drains and vents on threadolets for hydrotest at high and low points within each test section and Hex Plug them when you're finished.


**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/