General P&ID Review Recommendations 2

[ChEMatt]

I'm in a position now where I'm reviewing P&ID's for vendor-supplied equipment. In the past I've been in Operations where I merely updated these types of drawings.

I was wondering if you all would be able to provide some general guidelines as to any sort of procedure you use to review the drawings, and the things you ask yourself/look for while reviewing.

On the surface this probably seems like a stupid question, and perhaps it is, but I tend to like to turn my tasks into logical processes so I can check things off so I don't leave anything out.

For example:

Line Specs
Electrical
Process Control Schemes
Line Overpressure Situations
Proper Line Ratings and Spec Breaks
Potential Pocketed Lines
Incorrect connections between units (pumps, towers, vessels, etc.)
Needed isolation valves
Unneeded isolation valves

and so on...

Onwards,

Matt

 

[dtlb26]

You didn't mention your industry.

Consider doing a PHA or Hazop review for these P&IDs.

Some references:

http://www.uscg.mil/hq/gm/risk/E-Guidelines/RBDM/html/vol3/08/v3-08-03.htm#32

http://www.primatech.com/info/paper...n_improved_process_hazard_analysis_method.pdf

 

[ChEMatt]

CPI? In general we'll say I'm in the natural gas processing industry; more specifically we'll say MidStream. Amine sweetening, sulfur recovery, dehydration, etc.

I'm sure we'll do a HAZOP at some point in time but I we're doing a cursory overview to get the low-hanging fruit, so to speak.

Thanks for the references.

Onwards,

Matt

 

[JLSeagull]

In addition to the P&ID's look at the corresponding piping spec issues. Do you want weld end valves in acid gas? Assure that the elastomers are compatible with amine. Does the chiller have a way to vent inerts without losing the refrigerant?

Are there seperate control systems, i.e. a basic process control system or DCS; and a safety instrumented system or shutdown system? Do shutdown valves reflect position indication? Do they use transmitters for shutdown signals instead of switches such as pressure switches or temperature switches? Do they use newer measurement technologies or older technologies? For examples consider radar / guided wave radar / magnetic level gauges; other than orifice & dp for flow, ...

 

[BigInch]

Don't look so much for what is there, rather for what isn't there.

BigInch-born in the trenches.

http://virtualpipeline.spaces.msn.com

 

[reena1957]

Dear ChEMatt,
Make a simple start-up, Shut-down and emergency procedure write-up for the system and check if all the piping, valving and instrumentation is there in the PID to effect these abnormal operations starting from a clean plant to running plant to clean plant again. Include eqpt maintenance requirements like sparing, draining to closed and open drain systems. Instruments and exchangers may require flushing. BigInch has hit the nail on the head - look for what is not provided but for that you have to prepare a list of what is required at different stages of operation in the field as well as control room apart from Emergency shutdown systems.

 

[ScottyUK]

A few suggestions from the power industry:

Look for the contingency conditions: what happens if instrument air fails, electrical power fails, over-pressure occurs, etc. This would normally fall into a HazOp but often there are some easy things to pick eg an OAF valve where it should be CAF, missing PRV's, hydraulic actuators which either lock up or go soft in a power outage and so on.

What do you need for your PTW / safe system of work? DB&B, single isolation?

Look for fallbacks when the isolation you want doesn't hold: what are your options - is there another valve further back or are you looking at a plant outage?





----------------------------------

Sometimes I only open my mouth to swap feet...

 

[STYMIEDPIPER]

All valid points listed but ScottyUK is right on the money with this one.
You need to take a look at each situation regarding "what happens if this fails" and incorporate a design that can remedy the "what if it fails" question.
It appears that every heavy industrial facility upgrade is installing "double redundacy" for safety purposes.
SAFETY IS PARAMOUNT

 

[jeap]

Dear ChEMatt,

As you can see, there are a number of suggestions on how to review a P&ID. Most of them coming from people experienced in a particular area/specialty. Reviewing a P&ID is quite difficult if you don't understand the main object of the process/unit operation described into the diagram, and what Engineering level it belongs (basic or detailed engineering). For instance, if you review a Basic Engineering P&ID and you don't know that, maybe it seems you like a poor diagram because you won't find some obvious ancillary equipment, drains, etc. that must be included. It could be a waste of time for you making suggestions/comments on details when the aim of the review was the function of the entire process.

For me, a P&ID is or should be the most important reference for all engineering areas (talking abt project in the CPI). In order to make a good reading of a diagram you need some additional information coming from previous engineering level, eg:

a) Design basis (Including a brief description of the process)
b) Material and energy balances.
c) Project Piping classes.
d) Plot Plan (in some cases).
e) Level of redundancy assumed for instrument systems.

May be it could seems like a lot of previous information, but you don't need to review all the documents, those only are useful as references.

In general, one must 'ask' the P&ID (and a good P&ID should answer) for the next items:

a) What the process or unit operation is made for?
b) Are the equipments selected capable to perform that function in the process conditions?
c) Are the lines capable to handle the fluids at the design flowrate, pressure, temperature and chemical behaviour (corrosion)?
d) Are there enough instruments in order to control the process conditions as those were selected?
e) Operator/control system can "see" what is happen in the process units (more instruments)?
f) 'What if' (here is when a Hazop is convenient) process conditions change, for instance, in a process excursion?
g) What happen after months of operation? there are dirty fluids in the process?
etc.

Well, it is a complex issue, but I think only experience is necessary, so give it time....

Regards.





b)

 

[JLSeagull]

Use API RP 14C to flag some of the functions that should be controlled. API RP 14 C applies to offshore projects. It provides a good starting point for other continuous projects too.

 

[BigInch]

start of a list,

Equipment w essential info Equip#, temp, press, flows, power rating
Tanks
vessels
heat exchangers
pumps
meters
provers
filters
valves major block check valves, control, safety relief
valve actuator type
heaters
pipe w/ sizes, line no &/o line spec
vents, drains, purges
all safety features
ESD switches and station locations
flow directions
control set points pressures, flow, temperatures, etc.
signal type, electrical, pneumatic, etc. and routing
interconnects & process permissions & interlocks
level glasses, switches
relays
temperature sensors and transmitters
pressure sensors and transmitters
flow meters and transmitters


BigInch-born in the trenches.

http://virtualpipeline.spaces.msn.com

 

[jeap]

list....continued

Tanks: Conections Id (vg. letters to designate each), dimensions height/lenght and diameter, material of construction, supplier(advanced P+ID stages).

HE, pumps, compressors, etc: type, supplier, model, materials.

Filters: Mesh or other characteristic.

Lines: Slope, insulation, heat tracing, reducers (excentric, concentric), some distances vg. diameters before and after flowmeters, orifice restrictions w/diameter. Material and series changes.

General: limit of supply by provider, indication of skid-mounted equipment, indication of flow direction (really important).

 

[ChEMatt]

Ahhh, good list there Biggie. Thanks.

Great posts to all of you. Thanks for the help. Keep 'em comin!

Onwards,

Matt

 

[dcasto]

Here are a few other things that should be listed:

Specification Changes in:
Pressure rating
Materials
Codes used
Third party connections (ownership)

Other items:
Maximum levels in storage vessels
Car Seals or Locks
Normally Open or Closed valves

 

[Ashereng]

I am a simple man, so I keep things simple. If the simple things are done correctly, the more complex things I find, usually are also.

On a P&ID, I check for, amongst many:

Valves: Fail Open or Fail Close? Limit switches included? How many? Open Switch and/or Close Switch. What kind of actuator? Does acutator agree with fail position. Instrument air or instrument gas? If you are in cold climate, you either need to heat trace the valve, or the valve needs to be rated for cold (eg. LCC, stainless). Also, if you have a 300# ANSI stainless steel in a 300# ANSI service, check the MOP/MAWP as stainless has a lower pressure at the same temperature as compared to carbon steel.

PSV: Inlet/Outlet size included? Orifice desgination included? Sizing case indicated? Set/Relief point indicated? Usually, I like something along the lines of:
1C1
100 psi
Thermal

Tagging: Is it consistent with the leader sheets/legends?

Symbology: Is it consistent with the leader sheets/legends? This incudes line types.

Line thickness: If your compnay uses line thickness, then I would check also.

Anyhoot, like others have said, there are lots to check, and many ways.

"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

 

[mfelzien]

Interesting thread. I couldn't help but throwing some humor in about the Importance of 'Issued As Built'. It truly is.. 'a state of grace'. Everyone always remember the importance of field checking your P&IDs.


Have a good season.

 

[0707]

A P&I review is an interdisciplinary matter which should be dealt by all specialities involved and the HAZOP shouldn’t be forgot.

At the end after construction and during the commissioning there is always something missing and the P&I should be updated and reviewed as built for the client.