Connection Break specs 3

[10815L]

Hi,
I'm going to break the connection specs and need forum members input for correct action, my problem is hereunder;
Production facility (Production separator) is having following specs (all piping associated with production separator is 300#), oil line upto skid is 300# and i want to tie-in with 150# existing facility. Shell I break the specs from the down stream of control valve or from the skid outlet.
Thanks
10815L

 

[SeanB]

A sketch would be helpful.

 

[TD2K]

With a pressure spec break, you have to ask yourself "can a block valve downstream of that point be closed and if so, what happens?" If bad things can happen, how are you going to prevent them? With a class 300 system, I would be immediately thinking about potential overpresssure for the class 150 system I'm connecting to.

 

[SNORGY]

Or it could be that the separator package is simply over-spec'd relative to the service it is actually being placed into.

Evaluate your potential pressures and temperatures (coincident combinations thereof) upstream of the separator and see if you can experience in excess of 1965 kPag at 38 C or 1790 kPag at 93 C. If so, you need to safeguard the downstream piping. If not, you can re-size the separator PSV for new conditions appropriate for a 150# ANSI system. It sounds like the spec break is at the last 300# flange in the system, probably at the separator package skid edge. It has to occur before the first 150# flange or component anyway.

 

[10815L]

Hi TD2K & SNORGY,
Indeed this separator is well test separator and now my company want to use it as production separator. I already asked the supplier to change the psve set value to 500 psig from 1400psig and also asked for spec change from down stream of control vlave for tie in connection.
for the safety of control system i'm going to put the HIPP to protect the down stream equipments. now please guide me about my this approach is ok or not.
Thanks
10815l

 

[SNORGY]

So you actually started with a 600# ANSI separator that you have now fit into a 300# ANSI application by lowering the PSV set point from 1400 psig to 500 psig.

What is HIPP?

In any event, if you now again step down to 285 psig on the downstream side of the control valve, I think you will need another PSV on the downstream piping if you are following the ASME Code. Pipeline codes might allow you to use a pressure limiting system instead of the PSV. Depending on what HIPP means...I am not familiar with that acronym.

 

[TD2K]

HIPP - High Integrity Pressure Protection. Essentially the use of instrumentation, usually redundant devices, to prevent against overpressure.

 

[SNORGY]

So it's like SIL (Safe Instrumented Level)?

If so, are there any special licensing requirements (depending on the regulatory authority involved) for HIPP as there would be for SIL? I would imagine an engineering assessment would need to be on file as a minimum.

Years ago, we had clients who kind of grandfathered themselves for line heater installation after line heater installation making use of redundant pressure switches in lieu of PSVs downstream of the angle choke valve, in order to avoid the need for the continuously lit flare (at sour well sites). That approach still applies in some Provinces but it's a tough sell in others.

 

[SNORGY]

Hence my question regarding Code Of Construction.

 

[SeanB]

This is why I would like to see a sketch. You will have to carry the 300# rating up to the last valve in the system. Any valves in the 150# system will have to be CSO or better Locked Open or you have to install a PSV in the 150# system.

 

[10815L]

Hi SeanB,
For oil line, I can't keep CSO optionbecause oil is going to Electrostatic Dehydrator and these are operating at low pressure, 'ie' 40 psig.
Contractor is proposing ESDV vlave after oil LCV but i'm relectant to accept this because i never experience before this type of applications.
could you please explain this problem further.
thanks

 

[SeanB]

If there is any valve in the 150# line that can be closed to create a blocked discharge situation you have the potential to overpressure the 150# system. If you can't CSO the valve then you would need a PSV to protect the line.
Your contractor is proposing an ESDV. I assume to trip closed on high pressure. You would likely need redundant valves, each with an independent pressure transmitter to give you the required SIL rating.