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Title: About the Thread
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Dear All,

Good Morning!

I am starting this thread where I am going to put questions regarding P&ID review; as I am going through that phase right now.

So, Instead of putting different questions probably coming under the broad umbrella of 'P&IDs', I devised the way
to put all the future questions in this same thread; and just on top (as i did in this message) mentioned the title that speaks about the nature/topic of the question/message.

I request anybody whom going to ask any questions regrading the P&IDs in Technical Forum, please have them in this thread as per above advise (meaning having the title on top of each message).

In this way we can maintain a good database of questions easy for anybody to browse, scroll and serach.

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Title: P&ID Checklist
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Morning!

I hereby start with the first question as one goes for the first time to review P&IDs.
I would like to know about the criteria against which a piping egineer should review P&IDs; I
mean to which extent one should go deep into P&IDs.

Can anybody pls list down the information or the checklist against which a P&ID 'should' be reviewed by a Piping Engineer.

Thanks

First, from a Piping Group stand point there should be three people from Piping in any P&ID Review meeting.
1. The Lead Piping Design Supervisor
2. The Lead Piping Material Engineer
3. The Lead Piping Stress Engineer

Each of these people have different interests and different responsibilities for the ongoing project effort. However there is a great deal of overlap in the interests of each.

The Design Supervisor is interested in where each line starts and finishes, what is in the line, what the state of the commodity is, the pressure and temperature of each line, the material of each line. This interest is primarily for proper line routing, flexibility and support.

The Piping Material Engineer is interested in much of this same information but for different reasons. The Material engineers interest is so the correct material can be selected for the Line Class Specifications.

The Pipe Stress Engineer in interested the information that relates to the need for stress analysis and the determination of which lines must be submitted for format calculations.

It is a TEAM effort, nor a one man show.

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Title: Key Elements of the P&IDs to be Reviewed by Piping Design Team
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Dear Jop,

Thanks. I understand what you said. OK Let me be specific.

Being a design supervisor’s point of view, to which extent the design team should go in reviewing P&IDs.
Can you please summarize key elements that must be checked by the Piping Design team.

Regards

It is not easy to be specific. I wish I could be there in the review room and be able to guide people on what to ask and why.
To me a P&ID review is both a process and a milestone.
P&ID - One of the primary deliverables of the Process Engineer on any project.
P&ID Review - This is a group meeting held and chaired by the Process Engineer to discuss the plant/unit before the P&ID is issued for design. All changes, additions, deletions, notes, etc. are updated prior to the IFD release.
Issued For Design (IFD) - For the P&ID this issue is the start of detailed design for piping and most others on a projects.

P&ID Review-
The Process Engineer should pin all the P&ID's for the specific Unit up on the walls of a conference room. The attendees sit around a table where they can see the P&ID's and take notes on their reduced size copy on the table. The Process Engineer talks through all the equipment and all the lines and all the instruments and all the reactions happening in the equipment. The attendees ask questions about key issues that interest them or effect them as the meeting progresses.

The process engineer may state that a certain line must be "Sloped". Many process engineers just say "Slope" and they think that covers everything. The piping designer will want to understand why it must slope, which direction it must slope (up or down) and want to know how much slope. The main crude feed line from the Feed Heater to the Crude Fractionator is normally at about 800 degrees F, it is a critical line and (in my experience) it must slope up (1/4" per foot) in the direction of flow from the heaters to the Fractionator. This is so the vapor in the line rises and migrates to the Fractionator.

The piping designer wants the process engineer to yellow off each line and describe every thing that needs to be done in or by each line. Are there any critical control points? Are there any critical points of operation? Are there any critical repeat maintenance points (once or more times per shift).

The piping designer is responsible for turning the flat schematic diagram into a full three dimensional and functional plant. To do so he or she wants to know everything.

Ahh, I remember when that was the case .... the good old days!

From recent experience (over the last 10 years or so), I have found that a lot of projects I've worked on have adopted the "fast track" approach.

While this may appear to be the quickest, cheapest, most efficient method of project execution, it is frought with pitfalls - particularly for the piping designer.

With this method, piping design starts in tandem with P&ID development (... I know, I know ... ), and the piper often has nothing more than a draft PFD on which to base the equipment layouts.

You must guess equipment sizes based on preliminary PDF capacities, take a wild stab in the dark at line sizes, populate lines with valves, strainers, meters etc based on previous experience. While this is being done, the process guys are trying to put together P&IDs while you hound them for information.

As the P&IDS are developed, it is often found, especially in the utilities end of the projects, that the overall mass balances for the projects are nothing remotely like what they started out at, and so it is time to revisit all your previous line sizes.

This cycle will continue for many iterations of the P&ID until finally, the IFD P&ID arrives, in it's signed off, frozen for design form.

Piping then start getting kicked by project management for holding up the job .... "what do you mean it's not done yet, you have all the P&IDS!"

Unfortunately on these types of jobs, Issued for design (IFD) P&IDs, usually signal the checking phase of the piping process!

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Am I being cynical?
Have any of you guys shared these wonderful experiences?

Unfortunately I have found myself in this same boat for the last few years, with process, piping, mechanical, and structural all starting at the same time. In a situation like this, communication between the disciplines is key and when not functioning it will lead to major problems down the road.

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Title: Pump Suction Lines 'Flooded and Overflooded'
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Morning!

Just got little bit confused with two types of pump suction lines. Pls clear:

A) What difference b/w 'Overflow Pump Suction Line'. / 'Flooded oump suction' (I feel it is normal suction line running from equipment to pump; and should be flooded; in casse if pump is not self priming?).
and Do these two lines normally present in all centrifugal pumps?

B) Process book recommends 'Overflow pump suction lines are designed for about a one foot/second velocity, unless a higher velocity is necessary to keep small solids or precipitates in suspension.' <===== What could actually they meant by 'suspending the solids' and why would they like to do so.

C)Also in attached figure what could be possible reason fo having a backflow (indicated in red) to pump discharge line again.

Thanks

"C)In attached figure what could be possible reason for having a back flow (indicated in red) to pump discharge line again?"

This small 20mm (3/4") line around the Check Valve is called a "Warm-up Bypass" and to understand its purpose you must understand the pump service and operational and maintenance philosophy.
I am not there and I cannot talk to your Process Engineer so I must make some assumptions based on my past experiences.

So here goes.
I think that these pumps are in a "Hot" service. This is supported by the designation of "PP" for "Personnel Protection" insulation. The fluid in this circuit is possible the type that if it is allowed to cool too much it could be difficult to start the pump.
I think these pumps normally run with one operating and one on "Stand-By". This run/stand-by would be set on a fixed time cycle. This cycle might be 24 hours or 48 hours so that each pump will see near equal use and wear. This prevents the bearings in the shut down pump from developing flat spots and going dry.

The purpose of the "Warm-up Bypass" is to allow the hot fluid being discharged from one pump to go backwards down the discharge of the stand-by pump, around the check valve and through the pump to the suction side line. It is not normal to have a valve in this small line. It is more normal to just install a restriction orifice union. The orifice would have a small fixed hole for the flow. This small flow will keep the pump case warm so if the pump "Auto" start circuit turns the pump on the pump is not "frozen" and is not damaged.

Another way this can be (and is often is) done is to just drill a small hole in the disc of the check valve.

Items A & B

"Flooded Suction"
http://www.pumpworld.com/Flooded%20Suction.htm

"Overflow Suction"
I cannot find anything on "Overflow Suction" and I have never heard of this.

The line identification is made up of six groups of numbers and or letters (400-CL-040-9114-A2AS-PP), Please define what these are and what they mean for this project.
400 - Pipe size?
CL-?
040-?
9114-?
A2AS-?
PP- Insulation Code for "Personnel Protection"?

The more I look at the P&ID for these pumps the more questions I have.
1. What is the material of the pump Suction and Discharge lines?
2. What is the flange rating for these lines?
3. What is the wall schedule for these lines.
4. What is the realistic Operating temperature for these lines (not the Design Temperature)?

We know the nominal pipe sizes for these lines 400mm (16") for the Suction and 150mm (6") for the Discharge. But we do not know why there is this large difference in the line sizes. With a Discharge line size of 150mm we can assume that the pump discharge nozzle would be likely 100mm (4") or 150mm (6") but we do not know for sure. If the discharge nozzle is in fact no larger than 150mm then the Suction nozzle would normally be 200mm (8") or 250mm (10") maximum size. Understanding that then the next question is:
5. Why is the main suction line 400mm (16")?
6. If the main suction header is in fact 400mm, then what size are the suction block valves? And do they require Gear Operators?

Next there is a big question in my mind about other piping around these pumps. The pumps are "Hot" and being pumps they have Barings, Seals and Packing Glands. All of these will fail over time and need to be replaced. To replace any of these the pump must be shut down, made safe, drained and steamed out.
7. Where is the case vent?
8. Where is case drain?
9. Where is the Base Plate drain?
10. Where are the valved 20mm (3/4") connections (on the pipe near the suction block valve and the discharge block valve). These are for Nitrogen purge to blow out the fluid in the line and for Steam to steam-out the pump and all the piping?
11. Where is the drain funnel for pump drips to the base plate drain to the Oily Water Sewer?

There is also a possible need for cooling water for the Baring cooling, the Gland cooling and possibly pedestal cooling.
12. Do these pumps have one of the API 682 Standard Pump Seal Plans?
13. If so, which one?
14. How much of the API 682 piping is furnished by the pump vendor and how much is by the Engineering Contractor?
(Look at this web site for information and examples) http://www.scribd.com/doc/2462681/API-Flushing-Plans
After you look at this you will see that Piping IS involved. If there is a cooler then piping must supply the connections to the cooling water supply and return. If there is a Bleed or vent to the Flare then piping needs to supply the connection. Piping also is responsible for making sure that other process piping does not block access to these API 682 items for maintenance.

Maintenance items:
15. If those figure "8" blinds are large and weight more than one man (or two) can lift is there going to be lifting facilities available?
16. If so what kind?
17 How much room is required for access and removal?

Do what you can on these but don't forget to take time for lunch.

Hi Jop,

Right, here it goes....

400 - Pipe size? <==== Yes.
CL-? <=== Low Pressure Condesate
040-? <==== Unit No
9114-? <=== Line Sequence No
A2AS-? <=== Material Spec
PP- Insulation Code for "Personnel Protection"? <=== Yes Correct

The more I look at the P&ID for these pumps the more questions I have.
1. What is the material of the pump Suction and Discharge lines? <=== Probably A2AS, i.e. CS
2. What is the flange rating for these lines? <=== 150 lb as per A2AS spec...but pump nozzle is 300 lb flange
3. What is the wall schedule for these lines. <=== STD, as pe spec
4. What is the realistic Operating temperature for these lines (not the Design Temperature)? <== Line list shows design temperature only 150 deg C.

5. Why is the main suction line 400mm (16")? <=== well I really have no idea about that. Its the process decision.
6. If the main suction header is in fact 400mm, then what size are the suction block valves? And do they require Gear Operators? <=== Seems to me of same size as of pipe. P&ID not talks about any Gear Operator stuff. ****But Pls suggest what could Gear Operator valves have impact on Piping.

Qs 7-11, I hope new REV gives some Idea. Also pls see my Email.

12. Do these pumps have one of the API 682 Standard Pump Seal Plans? <=== YES
13. If so, which one? <=== Seal Category 2 / Code BSTFN
14. How much of the API 682 piping is furnished by the pump vendor and how much is by the Engineering Contractor? <=== For this I have sent info in the Email.

I hope Jop I have answered clearly.

Thanks

What does API 682 mean to a pump and to your process piping?

My answer:
Please check these links:
1.
http://www.amarinth.com/public_library/ ... system.jpg
This photo is of a standard end suction top discharge pump with API 682 Plan 53A accessories. See that vertical support with the small bottle and small piping. Your piping is in addition to the extra equipment. If your pump engineer requires API 682 accessories for a pump then you have extra piping and must route the discharge piping to clear these items.


2.
http://www.sundyne.com/cda/ind/pr/0,105 ... 89,00.html
This photo is of a high pressure side suction, side discharge horizontal split case pump with API 682 Pump accessories. Again, see those vertical supports with small bottles and small piping. That is furnished by the pump vendor. You still need to supply cooling water supply and return plus a closed vent to flare and nitrogen purge. In addition the main product suction and discharge cannot interfere with the API 682 items or the access to them.

Morning!

Could pls suggest:

1) Which side of valve pipe spec breaks be mentioned and why?
2) The control valve to contorl the flow is normally incorporated in a fallowing way (Flow direction is from 1 --> 6):
1) Normal pipe ----2)reducer----3)drain connection-----4) flow control valve------5) reducer again---6) normal pipe
Why the drain connection is located upstream of CV why not downstream.
3) Why the temperarture instrument should be downstream '10 pipedia' of pressure intrument.

Regards

1) Which side of a valve should a pipe spec breaks be shown and why?
The "Spec Break" (or Line Class change) should be on the down stream side of a higher rated valve or group of valves.
- If you are talking about just a single valve installation and the rest of the continuing line has no other valves, then the "Break" shall be on the down stream side of that valve.
- If you are talking about a control valve manifold where the upstream pressure is very high and the line class is higher than the ongoing downstream piping then: The control Valve must be rated for the higher line class, all other valves in the manifold must be rated for the higher line class, the "Spec Break" shall be on the downstream side of the Bypass valve (if more than one valve in the bypass, then on the down stream side of the last valve) and on the downstream side of the block valve on the downstream side of the control valve.

2) The control valve to control the flow is normally incorporated in a fallowing way (Flow direction is from 1 --> 6):
1) Normal pipe ----2)reducer----3)drain connection-----4) flow control valve------5) reducer again---6) normal pipe, Why is the drain connection located upstream of CV?
In general the popular thinking is that if the control valve "Fails" in the closed position then the high pressure commodity (gas or liquid) will be trapped on the upstream side of the control valve. Thus with the bleed on the "high pressure" side you will bleed it off before undoing the flanges. Safety!

Why not downstream?
Good question! In my opinion I think there should be a drain on both sides of any control valve.

3) Why should the temperature instrument be '10 pipe diameters downstream of pressure instrument.
Any temperature instrument is a probe that protrudes into or near the center of the line. This probe creates a disruption of the flow and causes a back pressure on the upstream side of the probe and a reduction of pressure on the downstream side of the probe.
The back pressure on the upstream side will distort the pressure gage reading just as the turbulence will on the downstream side.
Does this help?