6 replies to this topic

[kamal888]

Hi,

My cleint has asked me to explore if the PSV on the process line of a well site line heater can be deleted.

Reason being the well site maintenance flare is not a live one and will be used only with maintenance. If the above PSV is connected to this flare then the flare should be converted to a continuous flare with purge gas etc.

Besides legislation and regulatory factors can we avoid a PSV if there is no possibility of a blockage in the downstream? or any other reasons?

thanks

[djack77494]

if the PSV on the process line of a well site line heater can be deleted.

kamal,
It's hard for me to picture your system. I assume you are refering to an oil (production) well and that the produced fluids are routed through a heater. (Assuming) During maintenance, the well would be blocked in and a PSV is being considered to relieve any fluids in a blocked in section of pipe that may absorb heat if mis-operated. Let me know if I'm on the right track and I'll try to muster a response.
Regards,
Doug

[kamal888]

Hi Doug,

I am sorry I missed some vital information in my post. This is a sour gas plant discharging at 10,000 kpa. A line heater is provided at this well because the pressure is choked to 2000 kpa and gas conveyed to about 5 km 6" pipeline to a compressor station.

I have seen one drawing of a well site line heater where the PSV is deleted. I am trying to find out the conditions we can justify to delete a PSV on the process line.

Your second assumption is true that the flare is used for maintenence.

[Art Montemayor]

Kamal:

I think you have still failed to give Doug the basic data he solicited in order to correctly and intelligently respond to your problem.

I have done numerous oil and gas well development projects in the recent past and I think I have a idea of what you are trying to address.

First, I think you are using the wrong terminology in stating "I have seen one drawing of a well site line heater where the PSV is deleted." I think that the PSV WAS NEVER DELETED. I think that the PSV simply is not required. I write this because that has been my design criteria in similar projects.

It has always been customary, when developing gas well production, to make ALL the piping, fittings and valves of such a schedule that a PSV is not required. In other words, the system can safely tolerate a wellhead shut-in pressure should some one open the well choke valve while the system is blocked off further downstream. Since this is SOP (standard operating practice), then a PSV was never intended and consequently was NEVER DELETED. You can really confuse someone when you assume something that you have no facts or proof of. I am sure that what I am stating is the same case in your application. It is a common sense, practical, and SAFE engineering technique that is used in the "Upstream" oil and gas industry. Please correct me if I am wrong in my assumptions.

[kamal888]

Art,

I thank you for your time in throwing light on this subject. You are right I should not have used the work "deleted". That will mean there was indeed a PSV before and now it is deleted.

However you have understood my problem. So with a proper pipe sch. to accept the well shut-in pressure a PSV may not be required. I will take that suggestion and work out the reguired sch. of the pipe.

Also i am looking if this is a regulation of some kind in Canada that a PSV is mandatory to a sour line heater. I will post it here if I find it - but if there is something in your memory please share.

thanks

[Art Montemayor]

Kamal:

I am not familiar with Canadian regulations. I suspect they closely follow the USA's.

I would suspect that if you use a piping schedule such that the well's shut-in pressure will not be a problem, you are not required to have a PSV. The safety issue is very clear here. You, in my opinion, are perfectly correct in specifying a piping system such that you do not require a PSV. This is perfectly rational and safe - at least in the USA. And, don't forget the pipe fittings, valves, and instruments that also have to adapt themselves to a higher piping schedule value!

[JoeWong]

Hi,

My cleint has asked me to explore if the PSV on the process line of a well site line heater can be deleted.

Reason being the well site maintenance flare is not a live one and will be used only with maintenance. If the above PSV is connected to this flare then the flare should be converted to a continuous flare with purge gas etc.

Besides legislation and regulatory factors can we avoid a PSV if there is no possibility of a blockage in the downstream? or any other reasons?

thanks

Kamal,

Your response still doesn't provide sufficient information (to me)...

Have you consider the potential of of blocked-in-heat-on and fire case for the inline heater ? If you manage to rule out above cases, probably the PSV is not required.

FYI... in my previous project...maintenance barge will be equipped with live flare boom where the well shall be hooked up for well maintenance purpose...